Bio-filtration of helminth eggs and coliforms from municipal sewage for agricultural reuse in Peru
Yaya Beas, R.E. - \ 2016
Wageningen University. Promotor(en): Grietje Zeeman; Jules van Lier; Katarzyna Kujawa. - Wageningen : Wageningen University - ISBN 9789461734945 - 187
waste water treatment - waste water treatment plants - anaerobic treatment - helminth ova - anaerobic conditions - filtration - public health - afvalwaterbehandeling - afvalwaterbehandelingsinstallaties - anaërobe behandeling - wormeneitjes - anaërobe omstandigheden - filtratie - volksgezondheid
Where fresh water resources are scarce, treated wastewater becomes an attractive alternative for agricultural irrigation. However, the presence of large amounts of pathogens, even in treated wastewater, constraints its productive use, which is aggravated when sanitation and public health are poor. Among pathogenic indicators, helminth eggs are one of the most persistent microorganisms in treated effluents that may survive for several months in the irrigated fields. Application of upflow anaerobic sludge blanket (UASB) reactors could contribute to decrease the pathogenic content in wastewater due to physical and biological interactions with the anaerobic sludge bed, such as filtration and entrapment. In this thesis, the potential of the anaerobic sludge bed to particularly remove helminth eggs, was investigated in four phases. In the first phase, a temperature of 4° C was fixed in the UASB reactors in order to reduce the biological activity of the sludge. Hence, the anaerobic sludge filtration capacity at different upflow velocities was studied. This phase of the research was performed in two experiments. The first one using latex beads, simulating helminth eggs, and the second one using real helminth eggs, predominating in Peruvian wastewater. First experimental results show that increasing the upflow velocity led to a decrease in the removal efficiency of latex beads. At the lowest upflow velocity of 0.3 m·h−1, 100% removal of latex beads was reached. At an upflow velocity higher than 1 m·h−1, the removal efficiency dropped under 90 %. The degree of stabilisation of the sludge nor the sludge bed volume did not have a significant effect. Second experiment's results show that with upflow velocities below 1.5 m·h−1 real helminth eggs removal is greater than 70 %. Simultaneously tested, total and faecal coliforms removal was less than 83 %. The most common helminth eggs species found in the studied wastewater were Ascaris lumbricoides, Trichuris spp. and Strongyloides spp. The second phase was performed using two lab-scale UASB reactors at average ambient temperatures between 16.7 °C and 28.5 °C in the city of Lima (Peru). Ascaris suum eggs originating from infected pigs were selected as model organisms, considering their similarity, in terms of size and morphology, with Ascaris lumbricoides, a human pathogen. The sludge filtration capacity was determined, applying upflow velocities between 0.09 and 0.68 m·h−1. Average helminth eggs removals varied between 26 and 93 %, depending on upflow velocity and sludge bed height. 93 % removal was achieved when applying an upflow velocity of 0.09 m·h−1 and a sludge bed height reaching 19-25 % of the total reactor height. The third phase was conducted to test the effect of lower operational temperatures in the UASB reactor on the pathogen removal from domestic wastewater. Thus, a lab scale UASB reactor in the city of Puno (Peru), treating wastewater with temperatures varying between 11.3 and 14.3 °C for a period of 22 weeks after the start-up of the reactor, was used. Upflow velocities varied between 0.12 and 0.41 m·h−1. Results confirmed outcomes of the first phase of this research concerning helminth eggs removal, and consequently show that the sludge bed filtration capacity varied between 89 and 95 %. Faecal coliform removal varied between 0.9 and 2.1 log10 and E. coli removal between 0.8 and 1.6 log10. In general, removal efficiencies regarding helminth eggs and faecal coliforms, are not sufficient to comply with reuse standards. Finally, the capacity of Down Flow Hanging Sponge (DHS) reactors for removing faecal coliforms from domestic UASB reactor effluent for agricultural reuse in developing countries was investigated. Applied reactors were the cube type DHS (G1) without recirculation, the cube type DHS (G1) with recirculation and the curtain type DHS (G2). Results reveal an average faecal coliform removal of 4.74, 3.42 and 1.25 log10 respectively. These results comply with categories A, B and C of WHO (1989) standards, correspondingly. Therefore, treatment trains consisting of UASB-DHS reactors can possibly be applied when agricultural reuse is contemplated.
A Downflow Hanging Sponge (DHS) reactor for faecal coliform removal from an Upflow Anaerobic Sludge Bed (UASB) effluent
Yaya Beas, R.E. ; Kujawa-Roeleveld, K. ; Lier, J.B. van; Zeeman, G. - \ 2015
Water Science and Technology 72 (2015)11. - ISSN 0273-1223 - p. 2034 - 2044.
faecal coliforms - biochemical oxygen demand - chemical oxygen demand - waste water - waste water treatment - anaerobic treatment - waste water treatment plants - fecale coliformen - biochemisch zuurstofverbruik - chemisch zuurstofverbruik - afvalwater - afvalwaterbehandeling - anaërobe behandeling - afvalwaterbehandelingsinstallaties
This research was conducted to study the faecal coliforms removal capacity of Downflow Hanging Sponge (DHS) reactors as a post-treatment for an Upflow Anaerobic Sludge Blanket (UASB) reactor. Three long-term continuous lab-scale DHS reactors i.e. a reactor with cube type sponges without recirculation, a similar one with recirculation and a reactor with curtain type sponges. The porosities of the applied medium were 91%, 87% and 47% respectively. The organic loading rates were 0.86 kgCOD m-3 d-1, 0.53 kgCOD m-3 d-1 and 0.24 kgCOD m-3 d-1 correspondingly at hydraulic loading rates of 1.92 m3 m-2 d-1, 2.97 m3 m-2 d-1 and 1.32 m3 m-2 d-1, respectively. The corresponding averages for faecal coliform removal were 99.997%, 99.919% and 92.121% respectively. The WHO (1989) standards, in terms of faecal coliform content for unrestricted irrigation (Category A), was achieved with the effluent of the cube type DHS (G1) without recirculation. Restricted irrigation, category B and C is assigned to the effluent of the cube type with recirculation and the curtain type, respectively. Particularly for organic compounds, the effluent of evaluated DHS reactors complies with USEPA standards for irrigation of so called non-food crops like pasture for milking animals, fodder, fibre, and seed crops.
Influence of phenylacetic acid pulses on anaerobic digestion performance and archaeal community structure in WWTP sewage sludge digesters
Cabrol, L. ; Urra, J. ; Rosenkranz, F. ; Kroff, P.A. ; Plugge, C.M. ; Lesty, Y. ; Chamy, R. - \ 2015
Water Science and Technology 71 (2015)12. - ISSN 0273-1223 - p. 1790 - 1799.
rioolslib - anaërobe behandeling - anaërobe afbraak - sewage sludge - anaerobic treatment - anaerobic digestion - waste-water treatment - olive mill wastewaters - volatile fatty-acids - 16s ribosomal-rna - biogas production - degradation efficiency - microbial-populations - aromatic-compounds - phenolic-compounds - inhibition
The effect of phenylacetic acid (PAA) pulses on anaerobic digestion (AD) performance and archaeal community structure was evaluated in anaerobic digesters treating sewage sludge from a wastewater treatment plant (WWTP). Four pilot-scale continuous stirred tank reactors were set up at a full-scale municipal WWTP in Santiago de Chile, and fed with either primary or mixed sewage sludge. AD performance was evaluated by volatile fatty acid (VFA) and biogas production monitoring. Archaeal community structure was characterized by 16S rRNA denaturing gradient gel electrophoresis and band sequencing. In the primary sludge digester, a single PAA pulse at 200 mg L(-1) was sufficient to affect AD performance and archaeal community structure, resulting in long-term VFA accumulation, reduced biogas production and community shift from dominant acetoclastic (Methanosaeta concilii) to hydrogenotrophic (Methanospirillum hungatei) methanogens. By contrast, AD performance and archaeal community structure in the mixed sludge digester were stable and resistant to repeated PAA pulses at 200 and 600 mg L(-1). This work demonstrated that the effect of PAA pulses on methanogenic activity and archaeal community structure differed according to AD substrate, and suggests that better insights of the correlations between archaeal population dynamics and functional performance could help to better face toxic shocks in AD
Bodem Resetten: stap naar praktijktoepassing nieuwe methode van anaerobe grondontsmetting
Runia, W.T. ; Molendijk, L.P.G. ; Visser, J.H.M. ; Regeer, H. ; Feil, H. ; Meints, H. - \ 2015
Lelystad : PPO AGV (Rapport / PPO-AGV 648) - 45
akkerbouw - nematoda - meloidogyne chitwoodi - ditylenchus dipsaci - globodera pallida - waardplanten - gewasbescherming - bodeminvertebraten - nederland - inventarisaties - anaërobe behandeling - biologische grondontsmetting - duurzaamheid (sustainability) - onkruiden - nutrientenbeheer - arable farming - nematoda - meloidogyne chitwoodi - ditylenchus dipsaci - globodera pallida - host plants - plant protection - soil invertebrates - netherlands - inventories - anaerobic treatment - biological soil sterilization - sustainability - weeds - nutrient management
Door de toenemende problemen met schadelijke aaltjes in diverse teelten wordt naarstig gezocht naar alternatieve mogelijkheden om de grond te ontsmetten. Uitgangspunt van Wageningen UR en Agrifirm Plant is daarvoor een “groene” manier van grondbehandeling, die past in het algemene beleid van een duurzame gewasbescherming. Bodem Resetten is een nieuwe en unieke manier van anaerobe grondontsmetting en kan mogelijk een milieuvriendelijk en voor omwonenden veilig alternatief bieden. Er zijn voor het Bodem Resetten (BR) twee producten getest op effectiviteit: vaste Herbie® 72 en vloeibare Herbie® 87. Tevens is op zeer kleine schaal ook een plantaardige coating, als alternatief voor folie, onderzocht op gasdichtheid.
Anaerobic degradation of anionic surfactants by denitrifying bacteria
Paulo, A. - \ 2014
Wageningen University. Promotor(en): Fons Stams, co-promotor(en): P.A. García-Encina; Caroline Plugge. - Wageningen : Wageningen University - ISBN 9789462571242 - 166
oppervlaktespanningsverlagende stoffen - degradatie - anaërobe microbiologie - anaërobe behandeling - denitrificerende bacteriën - afvalwaterbehandeling - rioolwaterzuivering - pseudomonas syringae pv. pisi - surfactants - degradation - anaerobic microbiology - anaerobic treatment - denitrifying bacteria - waste water treatment - sewage treatment - pseudomonas syringae pv. pisi
De verwijdering van organische stof alsook van stikstof en fosfor wordt in RWZI vaak bewerkstelligd middels een anaëroob-anoxisch-aëroob (A2/O) proces. Met behulp van het A2/O proces kunnen oppervlakte-actieve stoffen al in het anaërobe dan wel anoxische compartiment afgebroken worden. In dit proefschrift wordt de isolatie van Pseudomonas stutzeri stam SN1 en Pseudomonas nitroreducens stam SN2 uit actief slib van een RWZI met een A2/O proces beschreven.
Phosphate and organic fertilizer recovery from black water
Tervahauta, T.H. - \ 2014
Wageningen University. Promotor(en): Cees Buisman; Grietje Zeeman, co-promotor(en): L. Hernandez Leal. - Wageningen : Wageningen University - ISBN 9789462570931 - 156
afvalwater - fosfaten - afvalwaterbehandeling - organische meststoffen - terugwinning - anaërobe behandeling - zware metalen - hergebruik van water - waste water - phosphates - waste water treatment - organic fertilizers - recovery - anaerobic treatment - heavy metals - water reuse
In this thesis the integration of treatment systems for black and grey water was investigated to improve resource recovery within source-separated sanitation concepts. Special focus was set on phosphate and organic fertilizer recovery from vacuum collected black water. Currently, the soil application of black water sludge is prohibited in the Netherlands due to elevated heavy metal concentrations.
Calcium phosphate granulation in anaerobic treatment of black water: a new approach to phosphorus recovery
Tervahauta, T.H. ; Weijden, R.D. van der; Flemming, R.L. ; Hernández, L. ; Zeeman, G. ; Buisman, C.J.N. - \ 2014
Water Research 48 (2014)1. - ISSN 0043-1354 - p. 632 - 642.
afvalwaterbehandeling - afvalhergebruik - slibzuivering - calciumfosfaten - fosfor - terugwinning - spectroscopie - infraroodspectroscopie - anaërobe behandeling - biobased economy - waste water treatment - waste utilization - sludge treatment - calcium phosphates - phosphorus - recovery - spectroscopy - infrared spectroscopy - anaerobic treatment - biobased economy - waste-water - precipitation - hydroxyapatite - struvite
Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1–2 mm, organic content of 33 wt%, and phosphorus content of 11–13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product.
Anaerobic wastewater treatment of high salinity wastewaters: impact on bioactivity and biomass retention
Ismail, S. - \ 2013
Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Hardy Temmink; Caroline Plugge. - Wageningen : Wageningen UR - ISBN 9789461738189 - 144
afvalwaterbehandeling - waterzuivering - afvalwater - anaërobe behandeling - zoutgehalte - biomassa - waste water treatment - water treatment - waste water - anaerobic treatment - salinity - biomass
Anaerobic sludge bed reactor systems like the upflow anaerobic sludge blanket (UASB) and expended granular sludge bed (EGSB) reactors are currently the mostly applied high-rate reactor systems for anaerobic wastewater treatment. The success of both systems has changed the world conception of wastewater treatment with energy recovery being an intrinsic part of the treatment process, avoidance of excess sludge problems and extremely low space requirement. Nevertheless, while broadening the UASB reactor application to a diverse type of wastewaters, high salinity wastewaters were found to give an adverse effect to the granulation processes. Accumulation of Na+at high concentrations produced weaker and fluffy granules endangering the applicability of the mentioned sludge bed systems. In this thesis, research was conducted to investigate the mechanisms of destabilization of the granules at high Na+concentrations, while trying to improve the granules’ properties. Chapter 1gives an overview of high salinity wastewaters, the application and the bottlenecks of anaerobic wastewater treatment (AnWT) technology under extreme conditions. Focus is given to the granulation process as a key factor in the operation of high rate anaerobic reactors. Indeed, it is a complex process that involves physicochemical as well as biological mechanisms. A short overview of the previous research on anaerobic wastewater treatment processes for high salinity wastewaters is discussed, followed by granulation theories and processes. Referring to the imbalance in the monovalent to divalent cation ratio, the Ca2+augmentation approach is discussed in this chapter as a tool to establish a favourable ratio for the required granulation process. The chapter also discusses the need for extracellular polymeric substances (EPS) production, depending on the types of substrates, as a major factor for a successful granulation process. Specifically for high Na+concentrations, also the importance of K+and more specifically the K+/Na+ratio is discussed as a control regulator to alleviate the negative effects of Na+. Finally, the review discusses microbiological aspects related to the anaerobic treatment of high salinity wastewaters such as the adaptation of sludge to high Na+concentrations and the presence of halophilic/halotolerent microorganisms and their application in anaerobic wastewater treatment.
In Chapter 2, the effects of high Na+concentrations on methanogenic sludge bed reactor systems were investigated. In three different UASB reactors a rapid acclimation to 5 or 15 g Na+/L was observed, showing satisfactory results for a period of 100 days, when the reactors were fed with a mixture of acetate, gelatine and ethanol. Loading rates up to at least 18 kg COD/m3.d gave a good COD removal performance and the cultivated sludge showed high specific methanogenic activities (SMA) on acetate, propionate, butyrate and H2compared to the inoculated granules. Remarkably, only the reactor which was operated at a lower COD (5 instead of 50 g/L) exhibited severe washout, probably due to the much shorter HRT that was applied, i.e. 12 hours compared to 120 hours. Interestingly, the SMA of the biomass that washed out from this reactor showed considerably higher SMAs than the washed-out biomass from the other reactors. The performance of the granular sludge systems in this study shows the appropriateness of anaerobic inocula, pre-grown under saline conditions for the anaerobic treatment of high salinity wastewater.
In Chapter 3the production of EPS in UASB reactor systems that were operated under high salinity conditions was investigated. Four different UASB reactors were operated at loading rates up to 22 kg COD/m3.d with different acetate:gelatine:starch ratios as the substrate. Reactors were fed with partially acidified and fully acidified substrates, i.e. PAS and FAS respectively, and Na+concentrations of either 10 or 20 g Na+/L. One of the reactors additionally received 1 g of Ca2+/L. All four reactors showed a good performance with COD removal efficiencies exceeding 90 %. Proteins were the dominant EPS and the PAS-fed granules gave much higher EPS concentrations than FAS-fed granules. However, the proteins concentration was found not dependent on the Na+ concentration in the feed. Interestingly, the granules from the reactors which were operated at a Na+/Ca2+ratio of 770 contained more polysaccharides than granules from reactors operated at a high Na+/Ca2+ratio of 1540. SEM images showed that that PAS-fed granule had a smoother granule surfaces than FAS-fed granule. PAS-fed granules also were considerably larger than FAS-fed granules. When the influent contained additional Ca2+, clear cracks or fissures could be observed on the surface of the granules. Na+ concentrations of 10 g/L seemed to increase the granule size, which may have been caused by swelling of the EPS matrix. Shear tests indicated that PAS-fed granules were stronger than the FAS fed granules and that Ca2+ addition had a positive effect on granule strength. The calcium content of these granules also was higher with 150 mg/g TSS compared to 60 mg/g TSS in the other reactors. Batch tests at high Na+concentrations confirmed calcium leaching from the granules. When granular sludge was exposed to 20 g Na+/L in batches, leaching of Ca2+from granules took place with a maximum obtained after 10 days. The calcium content of the granules decreased from approximately 85 to 52 mg/g TSS. Therefore, the highest Na+concentrations resulted in the weakest granules.
Chapter 4describes the results of batch incubation studies in which anaerobic granular sludge was augmented with 0.3 g Ca2+/L at Na+concentrations of 20 g/L. Experiments followed the previously described results of Chapter 3 showing that high Na+concentrations caused Ca2+leaching from anaerobic granules. Extensive SEM-EDX and SEM-BSE measurements confirm leaching of calcium from the granules when these are exposed to higher Na+ concentrations. Moreover Ca2+additions seemed to indeed maintain the Ca2+content of granular sludge.
Initial attachment of microorganism is very important for the development of granules and biofilms. Therefore, biofilm studies were conducted and explained in Chapter 5. Four different biofilm reactors with a non-woven carrier material were exposed to different Na+ concentrations (10 or 20 g/L) and inoculated with crushed granules. Acetate was used as the substrate. One of the reactors received 0.3 g Ca2+/L and another one 0.7 g K+/L. The reactors were operated as sequencing batches. The reactor fed with K+ gave the best performance. Lower salinity (10 compared to 20 g Na+/L) improved the performance and the reactor which received calcium gave the worst results. This finding contradicts with previous experiments in Chapter 3. However, the situation in the biofilm reactors is completely different because the biofilms had to form from scratch. FISH-CLSM images revealed no significant visible differences in microbial coverage (i.e. bacteria and archea) of the non-woven fabric, except for the calcium enriched reactor. After 40 days of operation, it was clearly observed that 20 g Na+/L does not prevent the initial microbial attachment under anaerobic conditions. From 16 sRNA DGGE measurements it was shown that the biofilms had a similar population and that this population did not change very much in time. The Archea were related to Methanosaeta harundinacae (acetoclastic), Methanolinea tarda and Methanobacterium subteraaneum (both hydrogenotrophic). Apparently these species can easily adapt to high salinity. However, the biofilms in the reactors did not show any of the known acetate-oxidizing bacteria that are expectedly needed for the production of H2from acetate as source for the growth of the found hydrogenotrophic Archea. Therefore, it is assumed that H2leakage by acetoclastic methanogen explain their presence in the reactor.
Four identical UASB reactors treating concentrated wastewaters (10 – 30 g COD/L) were operated at 20 g Na+/L and in detail described in Chapter 6. PAS and FAS substrates were fed to different reactors to compare the effect of different organic substrates on granule activity, stability and growth. The effect of calcium augmentation on anaerobic granules’ properties was studied by feeding two of the reactors with additional calcium at a concentration of 0.3 g Ca2+/L. A beneficial effect of potassium was demonstrated in Chapter 5 and it therefore was added to all the reactors, at a concentration of 0.7 g K+/L. The treatment performance of the reactors was compared during a period of 120 days at increasing volumetric organic loading rates (OLRs). Physicochemical and microbiological properties of the anaerobic granules were determined and discussed. The results showed that high COD removal efficiencies are possible at 20 g Na+/L, up to an organic loading rate of at least 14 g COD/L.d. At a loading rate of 25 g COD/L.d the performance and stability of all reactors deteriorated. There were indications that calcium augmentation had a positive effect on biomass retention, but this could not be further quantified. The microbial assays gave similar results as in Chapter 5. Compared to the inoculum, bacterial diversity in FAS-fed granules did not change significantly but was changed considerably in PAS-fed granules. Complex organic PAS feed resulted in more complex bacterial populations that were not related to archea. The bacterial presence of a dominant phylotype, belonging to the family of Marinilabiliaceaeand specifically Alkaliflexus imshenetskiiwas evidenced. Members of Marinilabiliaceae are capable of degrading polymeric substances such as starch and gelatine. The dominant archeal species in the reactors was related to Methanosaeta harundinacea. Methanosaetahave been found to play a major role in granulation
In Chapter 7the results of this research are discussed in a general context. Directions for further research are presented focussing on the increase in biomass activity and biomass retention in high salinity wastewaters by improving the adaptability of microbes and the anaerobic sludge granulation process.
New sanitation : bridging cities and agriculture
Zeeman, G. - \ 2012
Wageningen : Wageningen University, Wageningen UR - ISBN 9789461733252 - 23
nieuwe sanitatie - afvalwater - afvalwaterbehandeling - afval - kringlopen - volksgezondheid - anaërobe behandeling - terugwinning - new sanitation - waste water - waste water treatment - wastes - cycling - public health - anaerobic treatment - recovery
This inaugural lecture revolves around recovering raw materials such as phosphate, nitrogen, organic substances, energy and water from domestic waste and wastewater. If separated at source using less water, these materials can be recovered more efficiently and used as fertilisers in agriculture, for example. This is an important move at a time when raw materials are becoming increasingly scarce.
The effect of sludge recirculation rate on a UASB-digester treating domestic sewage at 15 °C
Zhang, L. ; Hendrickx, T.L.G. ; Kampman, C. ; Zeeman, G. ; Temmink, B.G. ; Weiguang Li, ; Buisman, C.J.N. - \ 2012
Water Science and Technology 66 (2012)12. - ISSN 0273-1223 - p. 2597 - 2603.
afvalwaterbehandeling - afvalwater - rioolwater - huishoudens - anaërobe behandeling - anaërobe verteerders - slibvergisting - recirculatiesystemen - temperatuur - zuurstofbehoefte - biogas - concentratie - efficiëntie - waste water treatment - waste water - sewage - households - anaerobic treatment - anaerobic digesters - sludge digestion - recirculating systems - temperature - oxygen requirement - biogas - concentration - efficiency - waste-water treatment - anaerobic-digestion - low-temperature
The anaerobic treatment of low strength domestic sewage at low temperature is an attractive and important topic at present. The upflow anaerobic sludge bed (UASB)-digester system is one of the anaerobic systems to challenge low temperature and concentrations. The effect of sludge recirculation rate on a UASB-digester system treating domestic sewage at 15 °C was studied in this research. A sludge recirculation rate of 0.9, 2.6 and 12.5% of the influent flow rate was investigated. The results showed that the total chemical oxygen demand (COD) removal efficiency rose with increasing sludge recirculation rate. A sludge recirculation rate of 0.9% of the influent flow rate led to organic solids accumulation in the UASB reactor. After the sludge recirculation rate increased from 0.9 to 2.6%, the stability of the UASB sludge was substantially improved from 0.37 to 0.15 g CH4-COD/g COD, and the biogas production in the digester went up from 2.9 to 7.4 L/d. The stability of the UASB sludge and biogas production in the digester were not significantly further improved by increasing sludge recirculation rate to 12.5% of the influent flow rate, but the biogas production in the UASB increased from 0.37 to 1.2 L/d. It is recommended to apply a maximum sludge recirculation rate of 2–2.5% of the influent flow rate in a UASB-digester system, as this still allows energy self-sufficiency of the system.
Autotrophic nitrogen removal from low strength waste water at low temperature
Hendrickx, T.L.G. ; Wang, Y. ; Kampman, C. ; Zeeman, G. ; Temmink, B.G. ; Buisman, C.J.N. - \ 2012
Water Research 46 (2012)7. - ISSN 0043-1354 - p. 2187 - 2193.
afvalwaterbehandeling - afvalwaterbehandelingsinstallaties - stikstof - verwijdering - denitrificatie - temperatuur - anaërobe behandeling - ammonium - oxidatie - energiebesparing - stedelijk afvalwater - waste water treatment - waste water treatment plants - nitrogen - removal - denitrification - temperature - anaerobic treatment - ammonium - oxidation - energy saving - municipal wastewater - anaerobic ammonium oxidation - treat sewage - reactor - system
Direct anaerobic treatment of municipal waste waters allows for energy recovery in the form of biogas. A further decrease in the energy requirement for waste water treatment can be achieved by removing the ammonium in the anaerobic effluent with an autotrophic process, such as anammox. Until now, anammox has mainly been used for treating warm (>30 °C) and concentrated (>500 mg N/L) waste streams. Application in the water line of municipal waste water treatment poses the challenges of a lower nitrogen concentration (
The effect of operational conditions on the hydrodynamic characteristics of the sludge bed in UASB reactors
Leitao, R.C. ; Santaellla, S.T. ; Haandel, A.C. van; Zeeman, G. ; Lettinga, G. - \ 2011
Water Science and Technology 64 (2011)9. - ISSN 0273-1223 - p. 1935 - 1941.
afvalwaterbehandeling - geactiveerd slib - anaërobe behandeling - slibzuivering - hydrodynamische dispersie - zuiveringsinstallaties - expansie - retentie - volume - waste water treatment - activated sludge - anaerobic treatment - sludge treatment - hydrodynamic dispersion - purification plants - expansion - retention - volume - settling characteristics - expansion characteristics - granular sludge - volume index - velocity - sewage - settleability - design
This work aims to evaluate the hydrodynamic properties of the sludge bed of Upflow Anaerobic Sludge Blanket (UASB) reactors based on its settleability and expansion characteristics. The methodologies used for the evaluation of the settleability of aerobic activated sludge, and for the expansibility of a sludge bed of Expanded Granular Sludge Bed reactors and Fluidised Bed Reactors were adapted and applied to the particular characteristics of the sludge of UASB reactors. An easy-to-build experimental set-up was developed to assess the parameters necessary for the equations of settleability and of expansibility. The results obtained from the sludges of seven differently operated reactors show that, for the treatment of low strength wastewater, settleability increased and expansibility decreased at decreased hydraulic retention time, from 6 to 1 h, and/or increased influent concentrations, from 136 to approximately 800 mg chemical oxygen demand/L. The results also show that it is useless to design an UASB reactor with a longer hydraulic retention time to cope with hydraulic shock loads, as a more expansible sludge will develop at such condition.
Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge
Luesken, F. ; Alen, T. van; Biezen, J. van der; Frijters, C. ; Toonen, G. ; Kampman, C. ; Hendrickx, T.L.G. ; Zeeman, G. ; Temmink, B.G. ; Strous, M. ; Camp, H.J.M. op den; Jetten, M.S.M. - \ 2011
Applied Microbiology and Biotechnology (2011). - ISSN 0175-7598
afvalwaterbehandeling - waterzuivering - anaërobe behandeling - methaan - oxidatie - bacteriën - nieuwe stam - denitrificerende micro-organismen - waste water treatment - water treatment - anaerobic treatment - methane - oxidation - bacteria - new phylum - denitrifying microorganisms - activated-sludge - microorganisms - populations - technology - reactor
Recently discovered microorganisms affiliated to the bacterial phylum NC10, named “Candidatus Methylomirabilis oxyfera”, perform nitrite-dependent anaerobic methane oxidation. These microorganisms could be important players in a novel way of anaerobic wastewater treatment where ammonium and residual dissolved methane might be removed at the expense of nitrate or nitrite. To find suitable inocula for reactor startup, ten selected wastewater treatment plants (WWTPs) located in The Netherlands were screened for the endogenous presence of M. oxyfera using molecular diagnostic methods. We could identify NC10 bacteria with 98% similarity to M. oxyfera in nine out of ten WWTPs tested. Sludge from one selected WWTP was used to start a new enrichment culture of NC10 bacteria. This enrichment was monitored using specific pmoA primers and M. oxyfera cells were visualized with fluorescence oligonucleotide probes. After 112 days, the enrichment consumed up to 0.4 mM NO2- per day. The results of this study show that appropriate sources of biomass, enrichment strategies, and diagnostic tools existed to start and monitor pilot scale tests for the implementation of nitrite-dependent methane oxidation in wastewater treatment at ambient temperature
Autogenerative high pressure digestion: anaerobic digestion and biogas upgrading in a single step reactor system
Lindeboom, R.E.F. ; Fermoso, F.G. ; Weijma, J. ; Zagt, K. ; Lier, J.B. van - \ 2011
Water Science and Technology 64 (2011)3. - ISSN 0273-1223 - p. 647 - 653.
biogas - gasproductie - biochemische omzettingen - methaan - anaërobe afbraak - drukbehandeling - kooldioxide - oplosbaarheid - anaërobe behandeling - afvalwaterbehandeling - biobased economy - biogas - gas production - biochemical pathways - methane - anaerobic digestion - pressure treatment - carbon dioxide - solubility - anaerobic treatment - waste water treatment - biobased economy
Conventional anaerobic digestion is a widely applied technology to produce biogas from organic wastes and residues. The biogas calorific value depends on the CH4 content which generally ranges between 55 and 65%. Biogas upgrading to so-called ‘green gas’, with natural gas quality, generally proceeds with add-on technologies, applicable only for biogas flows >100 m3/h. In the concept of autogenerative high pressure digestion (AHPD), methanogenic biomass builds up pressure inside the reactor. Since CO2 has a higher solubility than CH4, it will proportion more to the liquid phase at higher pressures. Therefore, AHPD biogas is characterised by a high CH4 content, reaching equilibrium values between 90 and 95% at a pressure of 3–90 bar. In addition, also H2S and NH3 are theoretically more soluble in the bulk liquid than CO2. Moreover, the water content of the already compressed biogas is calculated to have a dew point
Energy and phosphorus recovery from black water
Graaff, M.S. de; Temmink, B.G. ; Zeeman, G. ; Buisman, C.J.N. - \ 2011
Water Science and Technology 63 (2011)11. - ISSN 0273-1223 - p. 2759 - 2765.
afvalwaterbehandeling - urine - huishoudens - nieuwe sanitatie - energieterugwinning - fosfor - anaërobe behandeling - waste water treatment - urine - households - new sanitation - energy recovery - phosphorus - anaerobic treatment - nitrogen removal - waste-water - struvite - systems - precipitation - tank
Source-separated black water (BW) (toilet water) containing 38% of the organic material and 68% of the phosphorus in the total household waste (water) stream including kitchen waste, is a potential source for energy and phosphorus recovery. The energy recovered, in the form of electricity and heat, is more than sufficient for anaerobic treatment, nitrogen removal and phosphorus recovery. The phosphorus balance of an upflow anaerobic sludge blanket reactor treating concentrated BW showed a phosphorus conservation of 61% in the anaerobic effluent. Precipitation of phosphate as struvite from this stream resulted in a recovery of 0.22 kgP/p/y, representing 10% of the artificial phosphorus fertiliser production in the world. The remaining part of the phosphorus ended up in the anaerobic sludge, mainly due to precipitation (39%). Low dilution and a high pH favour the accumulation of phosphorus in the anaerobic sludge and this sludge could be used as a phosphorus-enriched organic fertiliser, provided that it is safe regarding heavy metals, pathogens and micro-pollutants.
Denitrificatie met opgelost methaan uit anaerobe vergisting: nieuwe mogelijkheid voor afvalwaterbehandeling
Hendrickx, T.L.G. ; Kampman, C. ; Luesken, F. ; Temmink, B.G. - \ 2010
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 14 (2010)15. - ISSN 0166-8439 - p. 34 - 36.
afvalwaterbehandeling - huishoudens - energieterugwinning - biogas - anaërobe behandeling - ammonium - methaan - denitrificatie - waterzuivering - zuiveringsinstallaties - waste water treatment - households - energy recovery - biogas - anaerobic treatment - ammonium - methane - denitrification - water treatment - purification plants
Huishoudelijk afvalwater bevat veel energie. Rioolwaterzuiveringsinstallaties hebben zodoende de potentie om energieproducerend te worden in plaats van energieconsumerend. Er zijn reeds initiatieven in gang gezet die zich richten op het terugwinnen van energie in de vorm van biogas door het vergisten van primair en secundair slib. Een meer directe route naar biogas is de anaerobe zuivering van het afvalwater. Het effluent van een anaerobe reactor bevat echter nog wel ammonium en opgelost methaan (een sterk broeikasgas). Beide kunnen omgezet worden met de recentelijk ontdekte DAMO-bacteriën: denitrificatie gekoppeld aan anaerobe methaanoxidatie. Dit biedt nieuwe mogelijkheden voor een energie-efficiënte afvalwaterbehandeling.
Hydrolysis inhibition of complex biowaste
Vasconcelos Fernandes, T. - \ 2010
Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Grietje Zeeman. - [S.l.] : S.n. - ISBN 9789085856818 - 182
agrarische afvalstoffen - dierlijke meststoffen - drijfmest - biomassa - hydrolyse - verwerking - anaërobe behandeling - anaërobe afbraak - afvalverwerking - biogas - biomassaconversie - agricultural wastes - animal manures - slurries - biomass - hydrolysis - processing - anaerobic treatment - anaerobic digestion - waste treatment - biogas - biomass conversion
The increasing demand of renewable energy sources and reuse of wastes, challenges our society for better technological solutions for energy production. Co-digestion of agricultural biowaste, such as animal manure and plant residues, offers an interesting contribution to the renewable energy strategies. The biogas plants, where the complex substrates, such as agricultural biowaste, get converted into biogas, are then able to produce electricity and heat, which can be used in the farm and delivered to the main electricity grid. Moreover, due to its decentralised nature, the implementation of small-scale biogas plants can supply renewable energy to people without the need for large-scale infrastructural networks such as electricity grids, thereby solving part of the populations’ energy demands.
The production of biogas from complex biowaste is rate-limited by the hydrolysis step of the anaerobic digestion process. However the hydrolysis step has been poorly described and not very well understood, resulting in non-optimized anaerobic digester volumes. Due to that, a review on the anaerobic hydrolysis step is in this thesis presented, together with ways to accelerate the hydrolysis, either by mitigating the revealed inhibiting compounds, by pre-treating difficultly hydrolysable substrates, or as is nowadays also applied, by adding hydrolytic enzymes to full scale biogas co-digestion plants.
In this thesis two compounds were studied in terms of its inhibiting effect on hydrolysis: ammonia nitrogen and Humic Matter (HM). Ammonia nitrogen did not show an inhibiting effect on anaerobic hydrolysis. On the other hand Humic acids-like (HAL) and Fulvic acids-like (FAL) extracted from fesh cow manure and silage maize, and in this thesis extensively described in terms of its chemical characteristics, showed a strong inhibiting effect on the hydrolysis step.
Plant matter is high in lignocellulosic biomass. Lignocellulosic biomass consists of lignin, which is resistant to anaerobic degradation, cellulose and hemicelluloses. Pre-treatment of plant material, is particularly important in order to increase biogas production during co-digestion of manure. Calcium hydroxide pre-treatment was shown, in this thesis, to improve the biodegradability of lignocellulosic biomass, especially for high lignin content substrates. Maleic acid generated the highest percentage of dissolved COD during pre-treatment, however its high market price makes it not so attractive as calcium hydroxyde.
Enzyme addition has recently gained the attention of biogas plants’ operators in order to accelerate hydrolysis, however further research is needed.
Long term partial nitritation of anaerobically treated black water and the emission of nitrous oxide
Graaff, M.S. de; Zeeman, G. ; Temmink, B.G. ; Loosdrecht, M.C.M. ; Buisman, C.J.N. - \ 2010
Water Research 44 (2010)7. - ISSN 0043-1354 - p. 2171 - 2178.
rioolafvalwater - rioolwater - excreten - huishoudens - afvoerwater - nieuwe sanitatie - afvalwaterbehandeling - nitrificatie - ammonium - anaërobe behandeling - sewage effluent - sewage - excreta - households - effluents - new sanitation - waste water treatment - nitrification - ammonium - anaerobic treatment - anammox reactor - waste-water - start-up - removal - ammonia - sharon - supernatant - management - digestion
Black water (toilet water) contains half the load of organic material and the major fraction of the nutrients nitrogen and phosphorus in a household and is 25 times more concentrated, when collected with a vacuum toilet, than the total wastewater stream from a Dutch household. This research focuses on the partial nitritation of anaerobically treated black water to produce an effluent suitable to feed to the anammox process. Successful partial nitritation was achieved at 34 °C and 25 °C and for a long period (almost 400 days in the second period at 25 °C) without strict process control a stable effluent at a ratio of 1.3 NO2-N/NH4-N was produced which is suitable to feed to the anammox process. Nitrite oxidizers were successfully outcompeted due to inhibition by free ammonia and nitrous acid and due to fluctuating conditions in SRT (1.0–17 days) and pH (from 6.3 to 7.7) in the reactor. Microbial analysis of the sludge confirmed the presence of mainly ammonium oxidizers. The emission of nitrous oxide (N2O) is of growing concern and it corresponded to 0.6–2.6% (average 1.9%) of the total nitrogen load
Combined carbon and nitrogen removal in integrated anaerobic/anoxic sludge bed reactors for the treatment of domestic sewage
Kassab, G. - \ 2009
Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): B. Klapwijk; M. Fayyad. - [S.l. : S.n. - ISBN 9789085853886 - 130
rioolwater - rioolslib - bioreactoren - anaërobe behandeling - anaërobe afbraak - denitrificatie - afvalwaterbehandeling - stikstof - verwijdering - koolstof - sewage - sewage sludge - bioreactors - anaerobic treatment - anaerobic digestion - denitrification - waste water treatment - nitrogen - removal - carbon
The main objective of this research is to assess the applicability and effectiveness of integrating anaerobic digestion and denitrification processes in a single sludge system. The integrated concept is of particular interest for the treatment of highstrength domestic wastewater and is accomplished by means of a sequential anaerobic-aerobic system. The anaerobic pre-treatment can consist of a single anaerobic stage or two anaerobic stages, conditioned mainly by the wastewater characteristics, the prevailing ambient temperatures and the scale of application
Characterization and treatment of grey water : option for (re)use
Abu-Ghunmi, L.N.A.H. - \ 2009
Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Grietje Zeeman; M. Fayyad. - [S.l. : S.n. - ISBN 9789085853930 - 194
afvalwaterbehandeling - hergebruik van water - fysicochemische eigenschappen - filtratie - aërobe behandeling - anaërobe behandeling - jordanië - waste water treatment - water reuse - physicochemical properties - filtration - aerobic treatment - anaerobic treatment - jordan
Addressing the issues of water shortage and appropriate sanitation in Jordan, domestic grey water treatment receives growing interest. Grey water comprises the domestic wastewater flows excluding waters associated with the toilet. The topics of concern for grey water are its characteristics, treatment and potentials for use after treatment. The target of this thesis is to develop a concept for treating grey water on-site for agricultural usage, thus sustaining a recycling process of grey water in Jordan. A review was made regarding the currently available grey water treatment technologies. In addition, grey water was quantitatively and qualitatively characterized, and then grey water reuse requirements including treatment, were analyzed. Biodegradability and biodegradation rates of the grey water were investigated for selecting appropriate design and operation criteria of the treatment technology to be developed. A low-tech semi-technical scale treatment system was tested to treat grey water discharges from a dormitory at the Jordan University campus. The treatment system was evaluated on obtained removal efficiencies and conformity of the effluent to the guidelines for the use of reclaimed water for irrigation in Jordan. Finally, the objectives, approaches and the results of each chapter are summarized, and then both the results and the potential of applying decentralised sanitation and reuse (DeSaR) concepts in Jordan are discussed.
Results show that storage and treatment are prerequisites for any type of grey water use. Grey water is aerobically and anaerobically biodegradable but the conversion rates are low. The core of the treatment concept consists of an integrated storage and anaerobic treatment unit, fed with a natural influent flow pattern, in a down-flow mode, up to a one day operational cycle, i.e. a variable HRT ≤ 24 hours. The second step consists of an aerobic post-treatment, mechanically aerated in a down-flow mode and a one day operational cycle, i.e. 24 hours HRT. Both units need insulation in the winter period. The final effluent, stable in winter and summer, meets the Jordanian standard, except for the pathogens, for usage in restricted irrigation. The achievable treatment efficiency for the CODtot is 44% in the anaerobic unit and 70% in the combined anaerobic-aerobic, unlike the high anaerobic and aerobic biodegradability in batch experiments, viz. 70 and 86%, respectively. The highest removal efficiency achieved was for the CODss fraction, viz. 71% in the anaerobic and 85% in the combined system. Therefore, it is expected that the CODtot removal efficiency of the system can be improved, by enhancing the CODcol and CODdis, removal, i.e. applying filtration and/or adding chemicals such as adsorbents, coagulants and/or flocculants to the treatment units.
Effects of high salinity wastewater on methanogenic sludge bed systems
Ismail, S. ; Gonzalez-Contreras, P.A. ; Jeison, D.A. ; Lier, J.B. van - \ 2008
Water Science and Technology 58 (2008)10. - ISSN 0273-1223 - p. 1963 - 1970.
afvalwaterbehandeling - slib - anaërobe behandeling - zoutgehalte - natrium - granulering - korrelslib - waste water treatment - sludges - anaerobic treatment - salinity - sodium - granulation - granular sludge - anaerobic granular sludge - reactor start-up - uasb reactor - digestion - calcium - impact
The attainable loading potentials of anaerobic sludge bed systems are strongly dependent on the growth of granular biomass with a particular wastewater. Experiments were conducted to determine the effects of high salinity wastewater on the biological and physical properties of methanogenic sludge. Sodium concentration of 5 g/L and 15 g/L were added to the influent of upflow anaerobic sludge bed (UASB) systems. After 100 days of operation, the methanogenic activity, extracellular polymeric substances (EPS), and granular strength were analyzed. The results show a high removal of organic matter but with accumulating propionate concentrations in the effluents. Meanwhile, wash-out of active methanogenic biomass in the effluent of the reactors was observed, likely as a results of the high Na+ concentrations. The rinsed biomass was characterized by a considerable specific methanogenic activity (SMA) on acetate, propionate and hydrogen as the substrates. On the other hand, results show that the SMA evolution was not affected by high salt concentrations. Also the amount and composition of extracellular polymeric substances (EPS) were similar in all sludges. However, results clearly show a sharp drop in the granule strength as a results of high Na+ concentration.
Anaerobic biodegradation of estrogens-hard to digest
Mes, T.Z.D. de; Kujawa, K. ; Zeeman, G. ; Lettinga, G. - \ 2008
Water Science and Technology 57 (2008)8. - ISSN 0273-1223 - p. 1177 - 1182.
geactiveerd slib - varkensmest - oestrogenen - afvalwaterbehandeling - anaërobe behandeling - biodegradatie - korrelslib - activated sludge - pig manure - oestrogens - waste water treatment - anaerobic treatment - biodegradation - granular sludge - waste-water treatment - removal - sewage - combination - behavior - sludge - plant
Although many publications are available on the fate of estrone (E1), 17b-estradiol (E2) and 17a-ethynylestradiol (EE2) during aerobic wastewater treatment, little is published on their fate under strictly anaerobic conditions. Present research investigated the digestibility of E1 and EE2, using digested pig manure, granular UASB sludge, UASB-septic tank sludge and activated sludge as inocula. Besides, actual concentrations were measured in a UASB septic tank treating black water. Under anaerobic conditions E1 is reduced to E2 but the extent of this reduction depends on type of inoculum. No significant loss of the sum of E1 and E2 and of EE2 was observed. Adsorption was responsible for a 32¿35% loss of E1 and E2 from the liquid phase in the UASB septic tank and the effluent still contained considerable concentrations of respectively 4.02 mg/l and 18.79 mg/l for E1 and E2 with a large fraction present in conjugated form. No EE2 was detected in the UASB effluent
Impact of high saline wastewaters on anaerobic granular sludge functionalities
Jeison, D.A. ; Rio, A. del; Lier, J.B. van - \ 2008
Water Science and Technology 57 (2008)6. - ISSN 0273-1223 - p. 815 - 819.
calcium - afvalwater - zout water - zoutgehalte - anaërobe behandeling - slib - zuiveringsinstallaties - vergelijkend onderzoek - korrelslib - calcium - waste water - saline water - salinity - anaerobic treatment - sludges - purification plants - comparative research - granular sludge - waste-water - adaptation - digestion - reactors
Three UASB reactors were operated at different salinity levels in order to assess the effects on the granular sludge properties. High levels of activity inhibition were observed at sodium concentrations over 7 g Na+/L, which resulted in low applicable organic loading rates and VFA accumulation in reactor effluents. However, either sludge adaptation or selection for saline resistant microorganisms occurred, which could be concluded from the observed increase in the 50% activity inhibitory concentrations of sodium during continuous flow experiments. Changes in Na+ susceptibility in time are likely to be expected when treating saline wastewaters. The latter was evidenced by the high sodium tolerance of granular methanogenic sludge coming from a full-scale industrial reactor treating such wastewater. High salinity conditions resulted in a reduced granule strength, predicting process instabilities during long term reactor operation. Batch tests showed that high sodium concentrations seemed to displace the calcium from the granular sludge, a factor known to affect anaerobic granules formation.
High-rate anaerobic wastewater treatment: diversifying from end-of the pipe treatment to resource oriented conversation techniques
Lier, J.B. van - \ 2008
Water Science and Technology 57 (2008)8. - ISSN 0273-1223 - p. 1137 - 1148.
anaërobe behandeling - energie - terugwinning - afvalwaterbehandeling - afvalwater - energiebehoud - overzichten - technologie - anaerobic treatment - energy - recovery - waste water treatment - waste water - energy conservation - reviews - technology - uasb reactor - wastewaters - sewage
Decades of developments and implementations in the field of high-rate anaerobic wastewater treatment have put the technology at a competitive level. With respect to sustainability and cost-effectiveness, anaerobic treatment has a much better score than many alternatives. Particularly, the energy conservation aspect, i.e. avoiding the loss of energy for destruction of organic matter, while energy is reclaimed from the organic waste constituents in the form of biogas, was an important driver in the development of such systems. Invoked by the present greenhouse alert, the energy involved is nowadays translated into carbon credits, providing another incentive to further implement anaerobic technology. Anaerobic conversion processes, however, offer much more than cost-effective treatment systems. Selective recovery of metals, effective desulphurization, recovery of nutrients, reductive detoxification, and anaerobic oxidation of specific compounds are examples of the potentials of anaerobic treatment. This paper presents a survey on the state of the art of full-scale anaerobic high-rate treatment of industrial wastewaters and highlights current trends in anaerobic developments.
Adapting UASB technology for sewage treatment in Palestine and Jordan
Mahmoud, N.A. ; Zeeman, G. ; Lier, J.B. van - \ 2008
Water Science and Technology 57 (2008)3. - ISSN 0273-1223 - p. 361 - 366.
afvalwaterbehandeling - anaërobe behandeling - rioolwater - tropisch klimaat - aanpassing - jordanië - zuiveringsinstallaties - palestina - waste water treatment - anaerobic treatment - sewage - tropical climate - adjustment - jordan - purification plants - palestine - domestic sewage - low-temperature - waste-water - reactor
High rate anaerobic technologies offer cost-effective solutions for "sewage" treatment in the temperate climate of Palestine and Jordan. However, local sewage characteristics demand amendments to the conventional UASB reactor design. A solution is found in a parallel operating digester unit that stabilises incoming solids and enriches the UASB sludge bed with methanogenic activity. The digester operational conditions were assessed by operating eight CSTRs fed with primary sludge. The results showed a high degree of sludge stabilization in the parallel digesters at SRTs10 and 15 days at process temperatures of 35 and 25°C, respectively. The technical feasibility of the UASB-digester combination was demonstrated by continuous flow pilot-scale experiments. A pilot UASB reactor was operated for 81 days at 6 hours HRT and 15°C and was fed with raw domestic sewage. This period was subsequently followed by an 83 day operation period incorporating a parallel digester unit, which was operated at 35°C. The UASB-digester combination achieved removal efficiencies of total, suspended, colloidal and dissolved CODs of respectively 66, 87, 44 and 30%. Preliminary model calculations indicated that a total reactor volume of the UASB-digester system corresponding to 8.6 hours HRT might suffice for sewage treatment in Palestine
Anaerobic wastewater treatment and membrane filtration: a one night stand or a sustainable relationship?
Jeison, D.A. ; Lier, J.B. van - \ 2008
Water Science and Technology 57 (2008)4. - ISSN 0273-1223 - p. 527 - 532.
afvalwaterbehandeling - vervuiling door afzetting - membranen - anaërobe afbraak - filtratie - anaërobe behandeling - deeltjesgrootte - slib - bioreactoren - waste water treatment - fouling - membranes - anaerobic digestion - filtration - anaerobic treatment - particle size - sludges - bioreactors - reactors
Several anaerobic membrane bioreactors (AnMBR) were operated, under various conditions, applying different reactor configurations. Applicable fluxes were strongly determined by the physical properties of the sludge present in the reactors. Results show that particle size is a key determining factor for the attainable fluxes. Under thermophilic conditions, small sludge particle size was observed, resulting in low critical fluxes reaching 6¿7 L/m2 h for the submerged configuration and acidified substrate. In contrast, under mesophilic conditions critical fluxes of 20 L/m2 h were obtained. The acidification level also showed a strong effect. Under thermophilic conditions, the presence of a significant fraction of non-acidified organic matter induced the growth of suspended acidogenic biomass that seriously affected the applicable fluxes, both in submerged and side-stream configurations. Under all conditions tested cake formation showed to be the limiting factor determining the applicable fluxes. Only low levels of irreversible fouling were observed. Due to technical and economical considerations, most interesting perspectives for the application of AnMBR are expected with the treatment of high-strength particulate wastewaters, and with extreme wastewaters characterised by high temperature, salinity, etc.
|Water en grondstoffen terugwinnen met anaerobe zuivering; is de historische veronachtzaming volledig achterhaald?
Lier, J.B. van - \ 2007
Spil 2007 (2007)237-238. - ISSN 0165-6252 - p. 23 - 26.
afvalwaterbehandeling - waterzuivering - anaërobe behandeling - waste water treatment - water treatment - anaerobic treatment
Uitleg waarom anaërobe zuiveringstechnologie de voorkeur verdient. Tevens wordt de betekenis van Wageningen UR bij het vermarkten van deze techologie genoemd
Anaerobie is veel meer dan louter afvalwaterzuivering
Lier, J.B. van - \ 2007
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 40 (2007)10. - ISSN 0166-8439 - p. 12 - 13.
anaërobe behandeling - afvalwaterbehandeling - afvalwater - waterzuivering - duurzaamheid (sustainability) - watergebruik - anaërobie - anaerobic treatment - waste water treatment - waste water - water treatment - sustainability - water use - anaerobiosis
De wereldwaterproblematiek vraagt grote aandacht. De millenniumdoelstellingen, die de Verenigde Naties in dit verband opgesteld hebben, zijn al diverse malen, ook in dit blad, naar voren gebracht en zullen voortdurend aandacht en inzet blijven vragen. Belangrijke vraag daarbij is hoe die doelstellingen bereikt moeten worden, zowel financieel als technisch. Critici zeggen dat ons systeem van waterbeschaving verkwistend is. In onze huizen verdunnen we de menselijke ontlasting met een factor honderd en meer, waardoor een immens afvalwaterprobleem ontstaat en bovendien de kosten van de preventieve verwijdering van ziektekiemen uit dat water niet meer in verhouding staan tot die van het behandelen van patiënten. Onze aanpak is een slecht voorbeeld voor ontwikkelingslanden, zeggen zij. De anaerobe afvalwaterbehandeling is een duurzaam alternatief dat volgens hen veel meer aandacht verdient. Reden voor een gesprek met prof. dr. ir. Jules van Lier, hoogleraar anaerobe afvalwaterbehandeling aan Wageningen Universiteit & Researchcentrum, die in november 2006 zijn inaugurele rede hield met als titel 'Meervoudig watergebruik, van last naar lust'
Microbial community analysis in sludge of anaerobic wastewater treatment systems : integrated culture-dependent and culture-independent approaches
Roest, C. - \ 2007
Wageningen University. Promotor(en): Willem de Vos; Fons Stams, co-promotor(en): A.D.L. Akkermans; Hauke Smidt. - [S.l.] : S.n. - ISBN 9789085048398 - 159
rioolslib - micro-organismen - anaërobe omstandigheden - afvalwaterbehandeling - anaërobe behandeling - stedelijk afvalwater - sewage sludge - microorganisms - anaerobic conditions - waste water treatment - anaerobic treatment - municipal wastewater
The need for clean water is increasing and anaerobic wastewater treatment can be used as a cost-effective solution for purification of organically polluted industrial waste streams. This thesis presents results from microbiological investigations of several full-scale and lab-scale anaerobic wastewater treatments systems. Anaerobic wastewater treatment has gained popularity and is now one of the key technologies in environmental biotechnology. However, knowledge of the microbial community structure – function relationships is limited. A combination of cultivation-dependent and cultivation-independent techniques can be used to improve this knowledge. In this thesis, batch serial dilution incubations from a methanol-fed lab-scale thermophilic (55°C) methanogenic bioreactor indicated that syntrophic interspecies hydrogen transfer-dependent methanol conversion is at least equally important as direct methanogenesis in this lab-scale reactor. A direct methanol-utilizing Methanomethylovorans hollandica-related strain was detected up to a 108-fold dilution, while Thermodesulfovibrio relatives and Methanothermobacter thermoautotrophicus strains were found till 109–fold dilutions in the presence of H2/CO2. Microbial diversity was further evaluated in two expanded granular sludge bed reactors fed with increasing oleic acid loading rates. The archaeal community in the reactor inoculated with granular sludge stayed quite stable and active, whereas the relative abundance of Methanosaeta-like organisms gradually decreased in the reactor inoculated with suspended sludge when oleate loads were increased to 8 kg of chemical oxygen demand m-3 day-1. Desulfomicrobium and Methanobacterium were found to dominate the start-up of a full-scale synthesis gas fed gas-lift reactor treating metal and sulphate rich wastewater. Most Probable Number (MPN) counts confirmed that heterotrophic sulphate reducing bacteria (SRB) were dominant (1011-1012 cells/g VSS) compared to homoacetogens (105-106 cells/g VSS) and methanogens (108-109cells/g VSS). Methanogens can still persist in sulphate-reducing bioreactors with short sludge retention time, since competition for hydrogen is determined by Monod kinetics and not by hydrogen threshold values. The microbial community in a full-scale upflow anaerobic sludge blanket reactor treating paper mill wastewater operated at 37°C was relatively stable over a period of 3 years as indicated by a high similarity (>75%) of denaturing gradient gel electrophoresis profiles of 16S ribosomal RNA gene fragments. Batch incubations at different temperatures resulted in microbial community changes. While the archaeal community composition differed significantly between incubations at 45 and 55°C, the bacterial composition changed between 37 and 45°C. Overall the bacterial community was dominated by Firmicutes (68% of the clones) and Delta-Proteobacteria (17% of the clones). A sequential degradation of first butyrate and then propionate at 37°C was linked to strong presence of Syntrophomonas sp. and Desulfobulbus propionicus, respectively. MPN series allowed estimating the number of micro-organisms per ml sludge that could use propionate without sulphate (109), propionate and sulphate (105), butyrate without sulphate (108), butyrate with sulphate (105), glucose (109) and H2/CO2 (1010). Archaea were mainly dominated by Methanosaeta, but also Crenarchaeota-relatives were identified. Bacterial clone sequences were related to a variety of different known species, with expected functions in anaerobic digestion like fermentative bacteria, syntrophic short chain fatty acids oxidisers and SRB. However, about 80% of the clones was similar to sequences in the database without close cultured relatives, but many of these appeared to be present in anaerobic environments. It is important to improve knowledge of these unknown micro-organisms and fast accurate monitoring and identification could be instrumental in realising this. Therefore, a pilot macro-array was developed and tested. It appeared that combining probes generated by PCR amplification of the V1 and V6 variable regions of the 16S rRNA gene provided accurate differentiation of closely related organisms. The integrated application of molecular and cultivation dependent analyses of microbiota structure and function of a broad variety of anaerobic wastewater treatment systems described in this thesis has been used to improve insight of the ecophysiology in such reactors. Some general commonalities of anaerobic systems have been found, but also system-specific characteristics. This provides potential identification of general and system-specific indicator populations, allowing improved diagnostics and reactor predictability.
Sulfate reduction at low pH in organic wastewaters
Lopes, S.I.C. - \ 2007
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): P. Lens; M.I. Capela. - [S.l.] : S.n. - ISBN 9789085047636 - 244
afvalwaterbehandeling - ph - verzuring - sulfaten - anaërobe behandeling - sulfaatreductie - waste water treatment - ph - acidification - sulfates - anaerobic treatment - sulfate reduction
The objective of the research described in this thesis was to investigate the operational window of dissimilatory sulfate reduction at low pH (6, 5 and 4) during the acidification of organic wastewaters. High sulfate reduction efficiencies at low pH are desirable for a more sustainable operation of acidification reactors in a two-phase wastewater treatment system, as pH control requires less caustic and/or the effluent recirculation from the second (methanogenic) reactor can be skipped. The low pH would also facilitate the removal of sulfide by stripping, as the fraction of gaseous sulfide increases with decreasing pH
Anaerobic membrane bioreactors for wastewater treatment: feasibility and potential applications
Jeison, D.A. - \ 2007
Wageningen University. Promotor(en): Jules van Lier. - [S.l.] : S.n. - ISBN 9789085046998 - 199
bioreactoren - anaërobe behandeling - afvalwaterbehandeling - membranen - biologische filtratie - biomassa - vervuiling door afzetting - bioreactors - anaerobic treatment - waste water treatment - membranes - biological filtration - biomass - fouling
Biomass retention is a necessary feature for the successful application of anaerobic digestion for wastewater treatment. Biofilms and granule formation are the traditional way to achieve such retention, enabling reactor operation at high biomass concentrations, and therefore at high organic loading rates. Membrane filtration represents an alternative way to achieve biomass retention. In membrane bioreactors, complete biomass retention can be achieved, irrespective of cells capacity to form biofilms or granules. Membrane bioreactor systems represent then a promising technology for those conditions where biomass aggregation cannot be ensured, or when an effluent completely free of suspended solids is of interest. In the present thesis the feasibility of anaerobic membrane bioreactors (AnMBR) is described, under a wide range of conditions and reactor configurations
Volatile organic sulfur compounds in anaerobic sludge and sediments: biodegradation and toxicity
Leerdam, R.C. van; Bok, F.A.M. de; Lomans, B.P. ; Stams, A.J.M. ; Lens, P.N.L. ; Janssen, A.J.H. - \ 2006
Environmental Toxicology and Chemistry 25 (2006)12. - ISSN 0730-7268 - p. 3101 - 3109.
microbiële afbraak - slib - sediment - anaërobe behandeling - afvalwaterbehandeling - sulfaten - thiolen - reductie - sulfaat - methanol - biodegradatie - microbial degradation - sludges - sediment - anaerobic treatment - waste water treatment - sulfates - thiols - reduction - sulfate - methanol - biodegradation - fresh-water sediments - dimethyl sulfide - membrane bioreactor - waste air - methanethiol - degradation - inhibition - removal - ph - methanogens
A variety of environmental samples was screened for anaerobic degradation of methanethiol, ethanethiol, propanethiol, dimethylsulfide, and dimethyldisulfide. All sludge and sediment samples degraded methanethiol, dimethylsulfide, and dimethyldisulfide anaerobically. In contrast, ethanethiol and propanethiol were not degraded by the samples investigated under any of the conditions tested. Methanethiol, dimethylsulfide, and dimethyldisulfide were mainly degraded by methanogenic archaea. In the presence of sulfate and the methanogenic inhibitor bromoethane sulfonate, degradation of these compounds coupled to sulfate reduction occurred as well, but at much lower rates. Besides their biodegradability, also the toxicity of methanethiol, ethanethiol, and propanethiol to methanogenesis with methanol, acetate, and H2/CO2 as the substrates was assessed. The 50% inhibition concentration of methanethiol on the methane production from these substrates ranged between 7 and 10 mM. The 50% inhibition concentration values of ethanethiol and propanethiol for the degradation of methanol and acetate were between 6 and 8 mM, whereas hydrogen consumers were less affected by ethanethiol and propanethiol, as indicated by their higher 50% inhibition concentration (14 mM). Sulfide inhibited methanethiol degradation already at relatively low concentrations: methanethiol degradation was almost completely inhibited at an initial sulfide concentration of 8 mM. These results define the operational limits of anaerobic technologies for the treatment of volatile organic sulfur compounds in sulfide-containing wastewater streams
Integrated treatment of tapioca processing industrial wastewater based on environmental bio-technology
Huynh Ngoc Phuong Mai, - \ 2006
Wageningen University. Promotor(en): Gatze Lettinga, co-promotor(en): N.T. Viet. - [S.l. ] : S.n. - ISBN 9789085044413 - 180
afvalwaterbehandeling - tapioca - voedselverwerking - anaërobe behandeling - rioolslib - vietnam - fabrieksafvalwater - waste water treatment - tapioca - food processing - anaerobic treatment - sewage sludge - vietnam - factory effluents
Tapioca processing wastewater containing high COD (9,630-13,760 mg/L), BOD (7,280-11,510 mg/L), SS (450-1,850 mg/L), total nitrogen (291-355 mg/L) total phosphorus (39-73 mg/L) and low pH (3.4-4.6) are one of the major causes of severe pollution to receiving source in South Vietnam. Based on the characteristics of tapioca processing wastewater, biological treatment processes are selected for study. In which the UAF, UASB, aeration tank and pond system are in series. For this treatment technology, the UAF reactor is used as pre-treatment for reducing of SS. The SS removal efficiencies ranged from 67-82%, equivalent to influent SS decreased from 450-1,850 mg/L to 148-290 mg/L. The core of treatment system is the UASB-reactor, which is responsible for the removal of organic matter. The OLR of UASB-reactor can achievedto 42 kgCOD/m 3 .d with HRT8.3-8.4 hours. The influent COD decreased from 10,498-14,330 mg/L to 1,082-2,178 mg/L, equivalent with treatment efficiencies ranged from 82.5-90.7%. The aeration tank and pond system are used as post-treatment. They take responsibility for the remainder of organic matter, nitrogen and phosphorus removal. With the HRT around 6-8 hours for aeration tank and 6-7 days for pond system, the effluent COD, total nitrogen and total phosphorus ranged from 78-94 mg/L, 4.5-5.7 mg/L, 7.3-7.9 mg/L, respectively. In the UASB-reactor, the granular sludge was observed after 20 days of operating at OLRof 6 kgCOD/m 3 .d. The study also showed that nutrients and trace elements are necessary for tapioca wastewater treatment using UASB-reactor, but only for start-up period, when OLR lowerthan 20 kgCOD/m 3 .d. The UASB-reactor was able to stand a shock load as the COD concentration three times higher than normal, in 24 hrs stretches, without any damage and the completed recovery took 2-3 days.The investigateon cyanide toxicity showed that cyanide exerts a distinct toxicity, in particular on the hydrolysis process of tapioca starch particles. Hence, hydrolysis of these particles was completed within 2 days in the control experiment (using 2g starch particles and 2 gVSS/L in the experiment conducted at 30 o C), while at a high cyanide concentration of 120 mgCN - /L it took up to 6 days. But compared to the hydrolysis process, the acidification process is much less affected by cyanide; acidification always proceeded immediately after hydrolysis of the starch particles. The experiments of reduction the cyanide toxicity showed that sulphide ions do not reduce the toxicity of cyanide through the formation of thiocyanate, but instead reinforce the toxicity of cyanide. And the addition of Fe 2+ significantly reduces the toxicity of cyanide on the hydrolysis and methanogenesis through the formation of the ferro-cyanide complex, but it does not stimulate the degradation of cyanide.The conclusions of the research showed that the solution comprising the implementation of the AnWT-technology combined with aerobic post-treatment, clearly demonstrates the big benefit of the energy cost savings and resource conservation together with its feasibility to meet really extremely severe discharge standards. It also shows how strong returns can be generated for investors using CDM. The estimate shows that the required treatment system with a capacity of 2,000 m 3 /d will produce 4,200 - 6,200 m 3 biogas per day (>60 % methane gas), which is equivalent to 2,600 - 3,800 liters of FO per day. And energy cost savings to the plant are estimated at 850 - 1,260 US$ per day.
Microbial aspects of synthesis gas fed bioreactors treating sulfate and metal rich wastewaters
Houten, B.H.G.W. van - \ 2006
Wageningen University. Promotor(en): Fons Stams, co-promotor(en): Hauke Smidt. - Wageningen : - ISBN 9789085043973 - 112
afvalwaterbehandeling - bioreactoren - anaërobe behandeling - methanobacteriaceae - sulfaat reducerende bacteriën - waste water treatment - bioreactors - anaerobic treatment - methanobacteriaceae - sulfate reducing bacteria
The use of synthesis gas fed sulfate-reducing bioreactors to simultaneously remove both oxidized sulfur compounds and metals shows great potential to treat wastewaters generated as a result of flue gas scrubbing, mining activities and galvanic processes. Detailed information about the phylogenetic and functional composition of the microbial communities within these bioreactors however was limited prior of this study. In order to understand and enable the effective control of performance of these bioreactors, an increased understanding of the microbial aspects of sulfate-reducing synthesis gas fed bioreactorsis required. 16S rRNA gene analysis demonstrated that the bacterial communities were dominated by the sulfate-reducing genera Desulfovibrio and Desuifomicrobium. Archaeal communities were comprised of microorganisms belonging to the methanogenic genus Methanobacterium. Synthesis gas fed bioreactors however were also able to sustain a diverse bacterial community, not limited to hydrogenotrophic microorganisms. Abundant 16S rRNA clones were also found which showed affiliation to the proteolytic microorganism Proteiniphilum acetatigenes and uncultured Thermotogales, while other clones clustered within the Chloroflexi subphylum I. A putative role for these organisms as scavengers of dead microbial cells was hypothesized. Due to the relatively short sludge retention time in these bioreactors hydrogen threshold concentrations are not reached, and instead Monod kinetic parameters controls hydrogen competition. As a result of fluctuations in operating conditions at full-scale a continuous state of hydrogen limitation may not be reached, resuiting in suppression of methanogenesis being a slow process. Limiting the carbon dioxide feed rate appeared to be a very effective selective tool to control methanogenesis at full scale, although it did not lead to the complete removal of methanogens from the system.
Heterotrophic SRB and homoacetogens were able to coexist when H2, CO2 and sulfate were supplied as the sole substrates as they were not limited by the same substrate; homoacetogens being hydrogen limited, while heterotrophic SRB were acetate limited. This consortium was able to compete effectively with methanogens, as the growth rate of even autotrophic methanogens is negatively affected by the lack of acetate. Even though homoacetogens are reported to have a high hydrogen threshold and a low ?™, they posses a high affinity (K5), which gives them a kinetic advantage over methanogens with intermediate growth rates (0.15 -0 .50 day"1) at 300CAs growth of methanogens is affected by the availability of acetate, limiting the addition of acetate to the feed of synthesis gas fed bioreactors may provide an additional tool to selectively control methanogenesis. In conclusion,the increased understanding of the microbial communities ofsu!fate-reducing synthesis gas fed bioreactors has provided greater insight into the competition for hydrogen and possibilities to control unwanted methanogenesis. Furthermore, the performance and stability of a full-scale reactor over a period of 128 weeks, demonstrate that this technology can be used successfully at full scale to treat sulfate and metal rich wastewaters.
The anaerobic treatment approach towards a more sustainable and robust environemnetal protection
Lettinga, G. - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 1 - 11.
afvalwaterbehandeling - biologische behandeling - milieubescherming - anaërobe behandeling - spijsvertering - korrels - waste water treatment - biological treatment - environmental protection - anaerobic treatment - digestion - granules - waste-water treatment - sludge bed reactor - removal - uasb
Anaerobic biological degradation processes (AnDe), when properly integrated with complementary biological and physical methods, constitute the ideal route to a sustainable protection of the life environment. However unfortunately for a smooth implementation of AnDe-processes drastic conceptual innovations are urgently needed in the field of environment protection; the present highly centralized approach in the public sanitation sector (CENSA) need to be substituted by a concept that focuses on optimal decentralization, problem prevention, self-sufficiency, resource recovery and reuse, with coupling to agriculture practices at or nearby the location (DESAR). Although a variety of excellent DESAR-based systems already are available and anaerobic digestion and treatment methods have found successful full-scale application for waste and wastewater treatment, there still is potential to improve these systems. Interesting questions to be elucidated are the effect of trace elements and macro-nutrients, the sludge immobilization phenomenon and the effect of environmental factors like temperature, pressure, mixing. Therefore tentatively a lot of challenging interdisciplinary research is waiting to attain further profitable innovations. Keywords Granular sludge-growth and manipulation; innovation; nutrients; paradigm; self-phasing; trace elements; valorization
Anaerobic digestion of concentrated wastewater in DESAR concept
Kujawa, K. ; Zeeman, G. - \ 2005
Utrecht : Stowa (STOWA rapport 14)
waste water treatment - anaerobic treatment - waste water - separation - water reuse - collection - afvalwaterbehandeling - anaërobe behandeling - afvalwater - scheiding - hergebruik van water - verzamelen
De haalbaarheid van anaërobe vergisting voor de behandeling van geconcentreerd zwartwater en keukenafval en zijn effect op het totale DESAH concept was de hoofdvraag van dit onderzoek. Deze haalbaarheid is uitgedrukt in: - het rendement dat kan worden verkregen in verschillende vergistingconfiguraties bedreven onder verschillende procesomstandigheden; - de kwaliteit en het hergebruikpotentieel van de verkregen producten. Het DESAH concept kent vele variatiemogelijkheden en daarmee is er geen universeel DESAH concept dat past in elke situatie. Er zijn echter elementen die identiek zijn voor alle scenario’s. Eén element is dat afvalwaterstromen gescheiden worden ingezameld op basis van bijvorbeeld de vervuilingsgraad, het type vervuiling en het hergebruikpotentieel van grondstoffen. Drie soorten grondstoffen zijn te onderscheiden: bio-energie (via de omzetting van organisch materiaal), nutrienten (stikstof, fosfaat en kalium) en water (via een geavanceerde nabehandeling van minder vervuilde afvalwaterstromen). De behandeling wordt zo geselecteerd dat het hergebruikpotentieel wordt behouden.
Thermophillic treatment by anaerobic granular sludge as an effective approach to accelerate the electron transfer and improve the reductive decolorization of azo dyes in bioreactors
Santos, A.B. dos; Traverse, J. ; Cervantes, F.J. ; Lier, J.B. van - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 363 - 369.
ontkleuring - temperatuur - textielindustrie - kleurstoffen (dyes) - azoverbindingen - afvalwaterbehandeling - anaërobe behandeling - slib - decolorization - temperature - textile industry - dyes - azo compounds - waste water treatment - anaerobic treatment - sludges - redox mediators - reactor - transformation - aqds
The effects of temperature, hydraulic retention time (HRT), and the redox mediator, thraquinone- 2,6-disulfonate (AQDS), on electron transfer and subsequent reductive decolorization of dyes rom textile wastewater was assessed in mesophilic and thermophilic anaerobic bioreactors. The results clearly show that compared to mesophilic anaerobic treatment, thermophilic treatment at 55 8C is an effective approach for increasing the electron transfer capacity in bioreactors, and thus improving the decolorization rates. At an HRT of 2.5 h and in the absence of AQDS, the color removal was 5.3-fold higher at 55 8C compared to 30 8C. Furthermore, similar decolorizations were found at 55 8C between the AQDS-free and AQDSsupplemented reactors, whereas a significant difference (up to 3.6-fold) on dye reduction occurred at 30 8C. Keywords Azo dye; color removal; electron transfer; anaerobic treatment; mesophilic; thermophilic
The effect of operational conditions on the performance of UASB reactors for domestic wastewater treatment
Leitao, R. ; Silva-Filho, J.A. ; Sanders, W.T.M. ; Haandel, A.C. van; Zeeman, G. ; Lettinga, G. - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 299 - 305.
afvalwaterbehandeling - anaërobe behandeling - prestatieniveau - verwijdering - chemisch zuurstofverbruik - slib - waste water treatment - anaerobic treatment - performance - removal - chemical oxygen demand - sludges
In this investigation, the performance of Upflow Anaerobic Sludge Blanket (UASB) reactors treating municipal wastewater was evaluated on the basis of: (i) COD removal efficiency, (ii) effluent variability, and (iii) pH stability. The experiments were performed using 8 pilot-scale UASB reactors (120 L) from which some of them were operated with different influent COD (CODInf ranging from 92 to 816 mg/L) and some at different hydraulic retention time (HRT ranging from 1 to 6 h). The results show that decreasing the CODInf1 or lowering the HRT, leads to decreased efficiencies and increased effluent variability. During this experiment, the reactors could treat efficiently sewage with concentration as low as 200 mg COD/L. They could also be operated satisfactorily at an HRT as low as 2 hours, without problems of operational stability. The maximum COD removal efficiency can be achieved at CODInf exceeding 300 mg/L and HRT of 6 h.
Effect of operational variables on nitrogen transformations in duckweed stabilization ponds
Caicedo Bejarano, J.R. - \ 2005
Wageningen University. Promotor(en): H.J. Gijzen, co-promotor(en): N.P. van der Steen. - [S.l.] : S.n. - ISBN 9789085041627 - 163
spirodela polyrhiza - stikstof - stikstofbalans - nitrificatie - anaërobe behandeling - algen - bezinkingsvijvers - spirodela polyrhiza - nitrogen - nitrogen balance - nitrification - anaerobic treatment - algae - stabilization ponds
There is a diversity of conventional technologies available for removal of pollutants from wastewater. Most of these technologies are aerobic alternatives with high construction cost and high energy consumption and require skilled personal for operation and maintenance. As a consequence, only countries with a high gross national product (GNP) can afford these options. Where these technologies were introduced in developing countries, in most cases these could not be operated sustainably, leading to loss of investments and continued water resource contamination. Extensive investments in wastewater treatment plants world-wide during the last decades have greatly reduced the organic loading of receiving water bodies in high GNP countries. Only recently, many of these plants were appropriated to remove nitrogen and phosphorus. The increasing use of chemical fertilizer may cause high levels of eutrophication in water bodies, which may induce algae blooms resulting in strong fluctuations in oxygen concentration. Oxygen depletion causes fish kill as well as odor problems.The situation in countries with a low GNP is worse than in the developed world. The unequal expansion of water supply coverage compared to the expansion in wastewater and sanitation services leads to increased contamination of surface and ground waters. The general trend is to use conventional WWT systems for big cities, but for medium and small sized cities non-conventional systems are often considered. Therefore, there is an urgent need to develop and improve low cost technologies for wastewater treatment that are within the economic and technological capabilities of developing countries. In countries like Colombia it is very common that the regulation controls mainly the removals of organic matter and suspended solids. Other parameters like nitrogen, phosphorus, pathogens, micro-contaminants are also crucial and need to be addressed. This makes a response via conventional technologies very expensive, and for developing regions in fact unachievable. It would be ideal if new technologies can provide besides the removal of organic matter and solids, resource recovery like the generation of biogas (energy production) or high quality biomass (animal fodder). At the moment, no technological packages appear to be readily available.Experience has shown that no single technology can offer an optimum treatment for the different components to be treated in wastewater or to recover them as valuable resources. Therefore an adequate combination of different technologies in an integrated system could convert a wastewater treatment into an attractive sustainable system. For example UASB reactor and duckweed ponds are relatively low cost technologies and their combination offers several advantages. Firstly, anaerobic treatment will reduce considerably the organic matter in the wastewater and convert it into methane, which can be used as a source of renewable energy. Secondly, the effluents of anaerobic treatment could be post-treated to meet discharge standards in duckweed ponds for nutrient recovery in the form of high quality biomass.At this point three valuable products can be listed: biogas for use as an energy source, biomass that can be used for aquaculture or animal feed and treated effluent that can be re-used in irrigation. A system that generates such by-products increases the feasibility and sustainability of pollution control programs. Furthermore, the products may help to address the increasing need for food production in the world. The development of duckweed pond technology has been concentrated on the study of the processes occurring within the ponds, with respect to organic matter, nitrogen, phosphorus and pathogen removal and the corresponding mechanisms. Further research is needed in order to have a good control of effluent nitrogen levels. There are still important questions to be answer like how to maximize nitrogen recovery via duckweed production, how to get good effluent levels depending on effluent reuse. If the effluent is going to be used in crop irrigation, to reduce nitrogen effluent concentration to 15-20 mg l -1 will be enough. If the effluent is going to be discharge in surface waters the nitrogen level would have to be reduced as much as possible. Therefore it is important to study how the design and combination of technologies could generate the required nitrogen effluent levels. The present work was focus on the study of the effect of different operational variables, like the effect of anaerobic pre-treatment, the combination of algae and duckweed ponds, the effect of pond depth on nitrogen transformation and removals.The effect of anaerobic pre-treatment on environmental and physicochemical characteristics of duckweed stabilization ponds was studied in Chapter 2 .The environmental and physicochemical conditions affect both plant growth and microbiological treatment processes in the system. Two series of continuous-flow pilot plants, composed of seven ponds in series each, were operated side by side. One system received artificial sewage with anaerobic pre-treatment, while the other system received the same wastewater without anaerobic pretreatment. pH, temperature, dissolved oxygen, alkalinity, conductivity, biochemical oxygen demand, total and ammonium nitrogen, nitrites and nitrates, and phosphorus were monitored under steady state conditions. It was found that pH levels were very stable in both systems with and without anaerobic pretreatment. Vertical temperature gradients were present during daytime but not as strong as they may occur in conventional stabilization ponds. Oxygen levels were significantly higher in the duckweed system with anaerobic pretreatment, especially in the top layer. (up to 2 mg O 2 l -1 ) than in the system without pretreatment (up to 1.2 mg O 2 l -1 ). Nevertheless, aeration rates were low in both systems. Both systems were efficient in removing organic matter. The system without pretreatment obtained 98% of BOD 5 removal in pond 4, so 12 days of retention time will be sufficient to reach high organic matter removal. The system with pretreatment obtained also 98% BOD 5 removal (92% in UASB reactor). In this case the duckweed ponds will serve as a polishing step for remaining organic matter. Nutrient removals were 37-48% for nitrogen and 45-50 % for phosphorus in the lines with and without pretreatment respectively.The main form of nitrogen in anaerobic effluent is ammonium. This is the preferred nitrogen source for duckweed, but at high levels it may become inhibitory to the plant. Renewal fed batch experiments at laboratory scale were performed (Chapter 3 ) to assess the effect of total ammonia (NH 3 + NH 4+ ) nitrogen and pH on the growth rate of the duckweed Spirodela polyrrhiza. The experiments were performed at different total ammonia nitrogen concentrations, different pH ranges and in three different growth media. The inhibition of duckweed growth by ammonium was found to be due to a combined effect of ammonium ions (NH 4+ ) and ammonia (NH 3 ), the relative importance of each one depending on pH.The effect of anaerobic pre-treatment on the performance of a duckweed stabilization pond system was assessed in a pilot plant located in the Ginebra Research Station-Colombia (Chapter 4). The pilot plant consisted of two lines of seven duckweed ponds in series. One line received de-gritted domestic wastewater and the other received effluent of a 250 m 3 Up-flow Anaerobic Sludge Blanket (UASB) reactor, treating the same wastewater. Both lines were operated at a total hydraulic retention time of 21 days.The systems were monitored for temperature, pH, oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, total phosphorus, biomass production, and different forms of nitrogen. No effect of anaerobic pretreatment was observed on pH and temperature in the two systems. Oxygen concentrations were higher in the system with UASB reactor. Although both systems complied with the Colombian regulation for BOD removal (> 85%)pretreatment with UASB reactor may contribute to the reduction of area requirement for the stabilization ponds. Effluent quality in terms of total suspended solids was excellent, i.e. 9 ± 2 and 4 ± 1 mg l -1 in the system with and without pre-treatment, respectively. Total nitrogen removals were 63 % and 68% and phosphorus removals were 24% and 29% in the system with and without pre-treatment, respectively. The differences between the two systems were found not to be significant. Duckweed biomass production was in the range of 54-90 g m -2 -d -1 (fresh weight) in the system with pre-treatment and 36-84 g m -2 -d -1 in the system without pre-treatment. Total biomass productions were significantly different at 92% level of confidence. Protein content was 35.1% and 36.6% for the system with and without pre-treatment, respectively.Nitrogen removal is nowadays one of the most important effluent treatment objectives because of the serious pollution problems it causes to the environment. How nitrogen is transformed and removed in duckweed ponds was studied and nitrogen balances were established (Chapter 5). The experimental system was the same as in the previous chapter. Ammonia volatilization was found to be not an important removal mechanism in duckweed ponds (less than 1%). Removal by sedimentation was also low at 2.1% and 4.7% for the systems with and without anaerobic pre-treatment, respectively. Instead, denitrification was found to be the most important removal mechanism (42% and 48%), followed by duckweed biomass up-take (15.6% and 15.1%). Average nitrogen biomass up-take rates were 199 mg N m -2 d -1 and 193 mg N m -2 d -1 for the system with and without pre-treatment, respectively. Nitrification rates were in the range of112 - 1190 mg N m -2d -1 and 58-1123 mg N m -2 d -1 for the system with and without anaerobic pretreatment respectively. Denitrification rates were in the range of 112 - 937 mg N m -2 d -1 and 59 - 1039 mg N m -2 d -1 for the system with and without pre-treatment respectively. The configuration of the system, in particular the down and up flow pattern seemed to have an important stimulating effect on denitrification rates, probably by causing alternative exposure of the pond water to aerobic and anoxic conditions.Although the potential of duckweed ponds for removing carbonaceous and suspended material from wastewater has been demonstrated, the system could be further optimized for nitrogen removal. The effect of introducing algae-ponds (aerobic zones) into a series of duckweed stabilization ponds on nitrification and denitrification (Chapter 6 ) was studied in two consecutive phases. During the first phase, the seven ponds of the pilot plant were fully covered with duckweed (Spirodela polyrrhiza). Before the start of the second phase, the duckweed cover was removed from ponds 1 and 3, with a view to allow algae growth in the 'open' ponds. The feed of the duckweed pond system consisted of the effluent of a real scale UASB reactor, which treated domestic wastewater from Ginebra-Colombia. The system was operated with a continuous flow to produce a hydraulic retention time (HRT) of 3 days per pond and a total HRT of 21 days. Effluent total nitrogen was significantly different in the two phases, with 13.8± 2.9 mg TN l -1 (63 % removal) and 3.7±1.5 mg TN l -1 (90%) for first and second phase, respectively.Denitrification was the most important removal mechanism during both phases, and amounted to 43.5 % and 76.2 % of influent nitrogen, in first and second phase, respectively. Ammonia volatilization and sedimentation were insignificant processes for nitrogen removal in both phases. Nitrification played an important role in nitrogen transformations in the duckweed systems and it was favored by the introduction of aerobic zones in ponds 1 and 3. Denitrification also played a key role in nitrogen transformations and removal. Despite the presence of oxygen in the water column, denitrification occurred, probably due to the anaerobic microenvironment of system biofilms. Higher nitrogen removal might be obtained in duckweed pond systems through the introduction of aerobic zones in early stages of the system. Where effluents cannot be reused for crop irrigation, strict nitrogen effluent criteria can be met using hybrid duckweed-algal ponds at considerably shorter hydraulic retention time compared to fully duckweed covered systems.The effect of pond depth on nitrogen removal in duckweed stabilization ponds was studied in Chapter 7. The pilot plant consisted of two lines with seven duckweed ponds in series, with different depths and fed with effluent of a laboratory scale UASB reactor. Three experimental conditions were studied: DSP1 with pond depth 0.7 m and HRT= 21 days, DSP2 with pond depth 0.4 m and HRT = 12 days, and DSP3 with pond depth 0.4 m and HRT = 21 days. The systems were monitored for pH, temperature and oxygen profiles, organic matter removal (BOD 5 ), nitrogen transformations, biomass production and biomass nitrogen content. Average total nitrogen removal rates were 598 mg N m -2 d -1 for DSP 1, 589 mg N m -2 d -1 for DSP 2 and 482 mg N m -2 d -1 for DSP 3. In spite of the lower nitrogen removal rate in DSP 3, it had higher removal efficiency (44 %, 43 % and 62 % for DSP 1, 2 and 3 respectively) due to the lower surface loading rate in this system. This shows that using the percentage of removal as a parameter for comparison should be done with care and the operational parameters of the compared systems should be taken into account. Denitrification was the most important nitrogen removal mechanism for the three DSPs. Nitrogen removal via biomass production was the second most important removal mechanism for the three experiments. Pond depth does not seem to determine nitrification or denitrification. Nitrification seems to be related to surface organic loading rate, while denitrification was related to BOD availability. The comparison between two pond systems with different depth, but operated at the same hydraulic surface loading rate (DSP 1 and 2) showed similar nitrogen removals in the shallower system as in the deeper system. This suggests that duckweed pond system could be designed with shallow depth without affecting surface loading and nitrogen removal efficiency. Nitrogen removal appeared to be governed by surface loading rate rather than by hydraulic retention time.Most of the research so far has been performed at laboratory or pilot scale. In the process of technology-development it is important to test findings at full scale. In Chapter 8 , the performance of a full scale duckweed pond was compared with a full scale algae pond treating effluent of a UASB reactor operated under similar conditions of climate, configuration, wastewater composition and loading rate. The real scale experimental system was composed of two continuous flow channels. One operated as an algae pond and the other as a duckweed pond ( Spirodela polyrrhiza and Lemna minor . ) . The volume of each channel was 225 m 3 , an average surface area of 322 m 2 , L/W ratio= 13.1 and depth of 0.7 m. The wastewater flow was 19.7 m 3 d -1 , for each system and the theoretical hydraulic retention time was 11.5 days. The ponds were monitored for the following parameters: Organic matter (BOD 5 ), total suspended solids (TSS), ammonium nitrogen (NH 4+ -N), total Kjeldahl nitrogen (TKN), nitrite nitrogen (NO 2 -N), nitrate nitrogen (NO 3 -N), total phosphor
Performance of UASB septic tank for treatment of concentrated black water within DESAR concept
Kujawa-Roeleveld, K. ; Fernandes, T. ; Wiryawan, Y. ; Tafwik, A. ; Visser, M. de; Zeeman, G. - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 307 - 313.
afvalwater - scheiding - anaërobe behandeling - hergebruik van water - afvalwaterbehandeling - verzamelen - waste water - separation - anaerobic treatment - water reuse - waste water treatment - collection - waste-water
Separation of wastewater streams produced in households according to their origin, degree of pollution and affinity to a specific treatment constitutes a starting point in the DESAR concept (decentralised sanitation and reuse). Concentrated black water and kitchen waste carry the highest load of organic matter and nutrients from all waste(water)streams generated from different human activities. Anaerobic digestion of concentrated black water is a core technology in the DESAR concept. The applicability of the UASB septic tank for treatment of concentrated black water was investigated under two different temperatures, 15 and 25 °C. The removal of total COD was dependent on the operational temperature and attained 61 and 74% respectively. A high removal of the suspended COD of 88 and 94% respectively was measured. Effluent nutrients were mainly in the soluble form. Precipitation of phosphate was observed. Effective sludge/water separation, long HRT and higher operational temperature contributed to a reduction of E. coli. Based on standards there is little risk of contamination with heavy metals when treated effluent is to be applied in agriculture as fertiliser.
Trace metal dynamics in methanol fed anaerobic granular sludge bed reactors
Zandvoort, M.H. - \ 2005
Wageningen University. Promotor(en): Gatze Lettinga, co-promotor(en): Piet Lens. - Wageningen : - ISBN 9789085041467 - 208
anaërobe behandeling - rioolslib - metalen - sporenelementen - milieuafbraak - anaerobic treatment - sewage sludge - metals - trace elements - environmental degradation
Trace metals are essential for anaerobic microorganisms, because they are present as cofactor in many of their enzymes. Therefore anaerobic wastewater treatment systems using these microorganisms to perform biological conversions are dependent on these metals for their (optimal) performance. In practice these metals are supplied to the influent when they are absent or insufficiently present in the wastewater. This supply is generally not very rational. However, such a rational metal supply is desired in order to reduce the costs, to minimize the introduction into the environment and to maximize the biological activity. To achieve this insight, in the trace metal dynamics in anaerobic granular sludge bed reactors is required. This thesis therefore focuses on the retention, accumulation and release of trace metals in anaerobic granular sludge and the factors affecting these processes. Further the impact of metal presence/absence and dosing on the anaerobic conversion of methanol was addressed
Effect of inoculum and sludge concentration of viscosity evolution of anaerobic granular sludges
Pevere, A. ; Guibaud, G. ; Hullebusch, E.D. van; Lens, P.N.L. ; Baudu, M. - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 509 - 514.
slib - anaërobe behandeling - reologische eigenschappen - spijsvertering - viscositeit - afvalwaterbehandeling - korrels - sludges - anaerobic treatment - rheological properties - digestion - viscosity - waste water treatment - granules - rheological characterization - sewage sludges - reactors - sorption - nickel - cobalt - uasb
The rheological behaviour of granular sludges (diameter 20-315 ¿m) originating from different anaerobic reactors was carried out using rotation tests. The sieved granular sludges suspensions display a non-Newtonian rheological behaviour and the limit viscosity was therefore used as a rheological parameter. The values obtained, which depend on the shear rate used, were strongly influenced by the total suspended solids (TSS) content of granular sludge and an exponential relation was found between the TSS and the rheological parameter limit viscosity. The increase of viscosity as a function of TSS content of the granular sludge as well as the increase of granule size underlines the importance of the interaction between granules in the evolution of this rheological parameter. Significant differences in granular sludge limit viscosity were found for granular sludge of different origins. All measurements performed with 10 g·l-1 TSS granular sludge indicate the ability of the chosen rheological parameter to describe different granular sludge quality.
Reductive decolourisation of azo dyes by mesophilic and thermophilic methanogenic consortia
Cervantes, F.J. ; Santos, A.B. dos; Madrid, M.P. de; Stams, A.J.M. ; Lier, J.B. van - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 351 - 356.
slib - ontkleuring - azoverbindingen - kleurstoffen (dyes) - anaërobe behandeling - redoxreacties - microbiële afbraak - afvalwaterbehandeling - sludges - decolorization - azo compounds - dyes - anaerobic treatment - redox reactions - microbial degradation - waste water treatment - anaerobic sludge - redox mediators - quinone-respiration - anthraquinone dyes - granular sludge - transformation - toxicity - bioreactors - inhibition - reactor
The contribution of acidogenic bacteria and methanogenic archaea on the reductive decolourisation of azo dyes was assessed in anaerobic granular sludge. Acidogenic bacteria appeared to play an important role in the decolourising processes when glucose was provided as an electron donor; whereas methanogenic archaea showed a minor role when this substrate was supplemented in excess. In the presence of the methanogenic substrates acetate, methanol, hydrogen and formate, methane production became important only after colour was totally removed from the batch assays. This retardation in methane production may be due to either a toxic effect imposed by the azo dyes or to the competitive behaviour of azo dyes to the methanogenic consortia for the available reducing equivalents. Keywords Azo dyes; decolourisation; methanogenic consortium; redox mediator; inhibitors
Reductive Decouloristation of Dyes by Thermophilic Anaerobic Granular Sludge
Bezerra Dos Santos, A. - \ 2005
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Jules van Lier; F.J. Cervantes. - [S.l.] : S.n. - ISBN 9789085041344 - 176
ontkleuring - kleurstoffen (dyes) - azoverbindingen - textielindustrie - bioreactoren - afvalwaterbehandeling - anaërobe behandeling - decolorization - dyes - azo compounds - textile industry - bioreactors - waste water treatment - anaerobic treatment
The colour removal achieved under anaerobic conditions is also called reductive decolourisation, which is composed of a biological part, i.e. the reducing equivalents are biologically generated, and a chemical part, i.e. the formed electrons reduce chemically the dyes. The overall objective of this research was to explore different strategies to increase the reduction of dyes in bioreactors by using thermophilic anaerobic granular sludge and redox mediators
Thermophilic (55 - 65°C) and extreme thermophilic (70 - 80°C) sulfate reduction in methanol and formate-fed UASB reactors
Vallero, M.V.G. ; Camarero, E. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
Biotechnology Progress 20 (2004)5. - ISSN 8756-7938 - p. 1382 - 1392.
anaërobe behandeling - afvalwaterbehandeling - methanol - reductie - sulfaten - temperatuur - anaerobic treatment - waste water treatment - methanol - reduction - sulfates - temperature - rate anaerobic reactor - volatile fatty-acids - 55-degrees-c - sludge - degradation - conversion - bacterium - methanogenesis - competition - performance
The feasibility of thermophilic (55-65 degreesC) and extreme thermophilic (70-80 degreesC) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures
The feasibility of thermophilic (55-65 degreesC) and extreme thermophilic (70-80 degreesC) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures. Full methanol and formate degradation at temperatures up to, respectively, 70 and 75 degreesC, were achieved when operating UASB reactors fed with sulfate rich (COD/SO42- = 0.5) synthetic wastewater. Methane-producing archaea (MPA) outcompeted sulfate-reducing bacteria (SRB) in the formate-fed UASB reactor at all temperatures tested (65-75 degreesC). In contrast, SRB outcompeted MPA in methanol-fed UASB reactors at temperatures equal to or exceeding 65 degreesC, whereas strong competition between SRB and MPA was observed in these reactors at 55 degreesC. A short-term (5 days) temperature increase from 55 to 65 degreesC was an effective strategy to suppress methanogenesis in methanol-fed sulfidogenic UASB reactors operated at 55 degreesC. Methanol was found to be a suitable electron donor for sulfate-reducing processes at a maximal temperature of 70 degreesC, with sulfide as the sole mineralization product of methanol degradation at that temperature.
Robustness of UASB Reactors Treating Sewage Under Tropical Conditions
Leitao, R. - \ 2004
Wageningen University. Promotor(en): Gatze Lettinga, co-promotor(en): Grietje Zeeman; A.C. van Haandel. - [S.l.] : S.n. - ISBN 9789085040453 - 160
anaërobe omstandigheden - rioolslib - afvalwaterbehandeling - retentie - dysregulatie - hydraulische apparatuur - tropisch klimaat - anaërobe behandeling - anaerobic conditions - sewage sludge - waste water treatment - retention - dysregulation - hydraulic equipment - tropical climate - anaerobic treatment
This PhD thesis presents results and discussions to elucidate the matters of performance and robustness of the Upflow Anaerobic Sludge Blanket (UASB) reactors for the treatment of municipal wastewater in tropical countries. The research focuses on the main operational parameters (hydraulic retention time -HRT, influent COD concentration - COD Inf , organic loading rate - OLR, and sludge retention time - SRT) that affect the UASB loading potentials and its performance in "steady state" conditions, and on the response of the system when submitted to transient conditions.
The experimental investigation was performed using 11 pilot-scale UASB reactors (120 L) which were organised into three sets: Set 1, five reactors were operated with the same hydraulic retention time (HRT = 6 h) and different COD Inf , ranging from 92 to 816 mg/L. Set 2, four reactors were operated with approximately the same COD Inf (~800 mg/L), but with different HRTs, ranging from 1 to 6 hours. Set 3, the HRTs were identical to the second phase but the COD Inf was adapted to have approximately the same OLR in the four reactors (~3.3 kgCOD/m 3 .day).
In the first experimental part of the research, data was collected in order to evaluate the "steady state" performance and robustness of UASB reactors on the basis of COD removal efficiency, effluent variability, and pH stability. After the "steady state" condition was achieved, the sludge of each reactor was tested in terms of Specific Methanogenic Activity (SMA), biodegradability, settleability and, expansibility. In the second part of the experimental research, the robustness and stability of the system were evaluated under hydraulic and organic shock loads. Four indicators were defined for that purpose: COD removal efficiency, effluent variability, pH stability, and recovery time.
Under "steady state" conditions, UASB reactors can treat sewage with COD as low as 200 mg/L, and HRT as low as 2 h, but the maximum efficiency is achieved with an HRT longer than 4h, and COD Inf higher than 300 mg/L. Effluent variability is highly dependent on the influent variability, showing that the reactors do not attenuate the daily fluctuation of the COD Inf . UASB reactors treating sewage in tropical countries are extremely stable with regards to pH and buffer capacity. With regards to the biological properties of the sludge, the reactors operated with a short HRT produce sludge with a high SMA. Moreover, sludge of reactors operated with a long HRT and with a low COD Inf resulted in low biodegradability. With respect to the hydrodynamic characteristics of the sludge, reactors operated with a high COD Inf and/or a short HRT produced sludges with high settleability and low expansibility. Results show that it is useless to design a UASB reactor with a longer HRT to cope with organic or hydraulic shock loads.
Under shock load conditions the reactors resulted in COD removal efficiencies in the same range as during "steady state" conditions. The effluent COD fluctuates in the same range of the COD Inf variation, showing that the reactors are unable to attenuate strong variation in the OLR. The recovery time from a shock load is always very short, as the reactors needed less than 18 hours after the shock ceased to resume performance. The reactors showed signals that they would acidify if the organic shock load continued. However, hydraulic shock loads barely affected the pH stability of the reactors.
Finally, the results obtained during this study showed that this kind of reactor is very robust with regards to the COD removal efficiency, as it keeps its maximum performance, in either "steady state" or transient conditions. Regarding to the pH stability, the UASB reactors also demonstrated extraordinary robustness, even when they are operated under extreme operational situations, which rarely occur in municipal wastewater treatment plants. When a shock load is imposed they need a very short time to recover. However, the UASB reactors are not robust with regard to effluent variability. Regarding this matter, the robustness of the reactors can be improved with the implementation of a secondary settler.
Anaerobic sludge granulation
Hulshoff Pol, L.W. ; Castro Lopes, S.I. de; Lettinga, G. ; Lens, P.N.L. - \ 2004
Water Research 38 (2004)6. - ISSN 0043-1354 - p. 1376 - 1389.
rioolslib - anaërobe behandeling - korrels - afvalwaterbehandeling - sewage sludge - anaerobic treatment - granules - waste water treatment - uasb reactors - start-up - molecular-mechanism - blanket reactors - bed reactors - hydrophobicity - pelletization - architecture - performance
This paper reviews different theories on anaerobic sludge granulation in UASB-reactors that have been proposed during the past two decades
This paper reviews different theories on anaerobic sludge granulation in UASB-reactors that have been proposed during the past two decades. The initial stages of the formation of anaerobic granules follow the same principles as biofilm formation of bacteria on solid surfaces. There exist strong evidence that inert carriers play an important positive role in granulation. Most researchers conclude that Methanosaeta concilii is a key organism in granulation. Only the Cape Town Hypothesis presumes that an autotrophic hydrogenotrophic organism, i.e., Methanobacterium strain AZ, growing under conditions of high H-2-pressures, is the key organism in granulation. Many authors focus on the initial stage of granulation, and only a few contributions discuss the latter stages in granulation: granule maturation and multiplication. Granule enhancing factors in the latter stages predominantly rely on manipulation of the selection pressure, through which selectively heavier sludge particles are retained in the UASB reactor. (C) 2003 Elsevier Ltd. All rights reserved.
Nickel and cobalt sorption on anaerobic granular sludges: kinetic and equilibrium studies
Hullebusch, E.D. van; Zandvoort, M.H. ; Lens, P.N.L. - \ 2004
Journal of Chemical Technology and Biotechnology 79 (2004)11. - ISSN 0268-2575 - p. 1219 - 1227.
slib - nikkel - kobalt - sorptie - kinetica - anaërobe behandeling - afvalwaterbehandeling - sludges - nickel - cobalt - sorption - kinetics - anaerobic treatment - waste water treatment - pseudomonas-fluorescens 4f39 - sphagnum moss peat - heavy-metals - aqueous-solution - waste-water - extracellular polymers - methanol degradation - removal - biosorption - ions
The kinetics and equilibria of sorption of the divalent metal ions cobalt and nickel onto anaerobic granular sludge are described. Single component and binary equimolar systems were studied at different pH values (pH 6, 7 and 8). The kinetic modelling of metal sorption by anaerobic granular sludge has been carried out using Lagergren equations
The kinetics and equilibria of sorption of the divalent metal ions cobalt and nickel onto anaerobic granular sludge are described. Single component and binary equimolar systems were studied at different pH values (pH 6, 7 and 8). The kinetic modelling of metal sorption by anaerobic granular sludge has been carried out using Lagergren equations. On fitting the experimental kinetic data both in first and pseudo-second-order equations, the regression analysis of a pseudo-second-order equation gave a higher r(2) value, indicating that both external mass transfer and intra-particle diffusion are involved in the sorption process. The experimental isotherm data were analysed using the Langmuir, Freundlich and Redlich-Peterson equations. The Redlich isotherm, a combination of the Langmuir and Freundlich equations, was found to have the highest regression correlation coefficients at pH 7. At pH 8, the Langmuir mechanism dominated for cobalt and nickel adsorption. In contrast, at pH 6, the Freundlich equation gave a better correlation coefficient which suggests a more heterogeneous adsorption at that pH. The maximal adsorption capacity of the granular sludge, as determined by the Langmuir equation, for cobalt or nickel in single systems (8.92 mg g(-1) Co TSS; 9.41 mg g(-1) Ni TSS, pH 7) compared with binary systems (8.06 mg g(-1) Co TSS; 8.43 mg g(-1) Ni TSS, pH 7) showed no great difference in the accumulation of these metals onto granular sludge. (C) 2004 Society of Chemical Industry.
Effect of different redox mediators during thermophilic azo dye reduction by anaerobic granular sludge and comparative study between mesophilic (30C) and thermophilic (55C) treatments for decolourisation of textile wastewaters
Bezerra Dos Santos, A. ; Bisschops, I.A.E. ; Cervantes, F.J. ; Lier, J.B. van - \ 2004
Chemosphere 55 (2004)9. - ISSN 0045-6535 - p. 1149 - 1157.
afvalwater - degradatie - consortia - toxiciteit - waterverontreiniging - ontkleuring - anaërobe behandeling - afvalwaterbehandeling - redoxreacties - azoverbindingen - kleurstoffen (dyes) - slib - waste water - degradation - consortia - toxicity - water pollution - decolorization - anaerobic treatment - waste water treatment - redox reactions - azo compounds - dyes - sludges - waste-water - reactor - carbon - bn6
The impact of different redox mediators on colour removal of azo dye model compounds and textile wastewater by thermophilic anaerobic granular sludge (55 C) was investigated in batch assays. Additionally, a comparative study between mesophilic (30 C) and thermophilic (55 C) colour removal was performed with textile wastewater, either in the presence or absence of a redox mediator
The impact of different redox mediators on colour removal of azo dye model compounds and textile wastewater by thermophilic anaerobic granular sludge (55 degreesC was investigated in batch assays. Additionally, a comparative study between mesophilic (30 degreesC and thermophilic (55 degreesC colour removal was performed with textile wastewater, either in the presence or absence of a redox mediator. The present work clearly evidences the advantage of colour removal at 55 degreesC compared with 30 degreesC when dealing with azo coloured wastewaters. The impact of the redox mediators anthraquinone-2,6-disulfonate (AQDS), anthraquinone-2-sulfonate (AQS) and riboflavin was evident with all dyes, increasing decolourisation rates up to 8-fold compared with the mediator-free incubations. The generation of the hydroquinone form AH(2)QDS, i.e. the reduced form of AQDS, was extremely accelerated at 55 degreesC compared with 30 degreesC. Furthermore, no lag-phase was observed at 55 degreesC. Based on the present results we postulate that the production/transfer of reducing equivalents was the process rate-limiting step, which was accelerated by the temperature increase. It is conclusively stated that 55 degreesC is a more effective temperature for azo dye reduction than 30 degreesC which on the one hand can be attributed to the faster production/transfer of reducing equivalents, but also to the decrease in activation energy requirements. (C) 2004 Elsevier Ltd. All rights reserved.
Effect of carbon monoxide, hydrogen and sulfate on thermophilic (55°C) hydrogenogenic carbon monoxide conversion in two anaerobic bioreactor sludges
Sipma, J. ; Meulepas, R.J.W. ; Stams, A.J.M. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
Applied Microbiology and Biotechnology 64 (2004)3. - ISSN 0175-7598 - p. 421 - 428.
slib - anaërobe behandeling - koolmonoxide - afvalwaterbehandeling - bioreactoren - sludges - anaerobic treatment - carbon monoxide - waste water treatment - bioreactors - methanogenic bacteria - synthesis-gas - energy - reduction - growth - metabolism - oxidation - reactor - co2
The conversion routes of carbon monoxide (CO) at 55°C by full-scale grown anaerobic sludges treating paper mill and distillery wastewater were elucidated. Inhibition experiments with 2-bromoethanesulfonate (BES) and vancomycin showed that CO conversion was performed by a hydrogenogenic population and that its products, i.e. hydrogen and CO2, were subsequently used by methanogens, homo-acetogens or sulfate reducers depending on the sludge source and inhibitors supplied. Direct methanogenic CO conversion occurred only at low CO concentrations [partial pressure of CO (P CO) 1.6 bar), indicating that CO-rich synthesis gas
The conversion routes of carbon monoxide (CO) at 55degreesC by full-scale grown anaerobic sludges treating paper mill and distillery wastewater were elucidated. Inhibition experiments with 2-bromoethanesulfonate (BES) and vancomycin showed that CO conversion was performed by a hydrogenogenic population and that its products, i.e. hydrogen and CO2, were subsequently used by methanogens, homo-acetogens or sulfate reducers depending on the sludge source and inhibitors supplied. Direct methanogenic CO conversion occurred only at low CO concentrations [partial pressure of CO (P-CO) 1.6 bar), indicating that CO-rich synthesis gas can be used efficiently as an electron donor for biological sulfate reduction.