Bioflocculation of wastewater organic matter at short retention times
Faust, L. - \ 2014
Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Hardy Temmink. - Wageningen : Wageningen University - ISBN 9789462571716 - 153
afvalwaterbehandeling - uitvlokking - bioreactoren - geactiveerd slib - organische verbindingen - biopolymeren - energieterugwinning - waste water treatment - flocculation - bioreactors - activated sludge - organic compounds - biopolymers - energy recovery
Low concentration of powdered activated carbon decreases fouling in membrane bioreactors
Remy, M.J.J. - \ 2012
Wageningen University. Promotor(en): Wim Rulkens, co-promotor(en): Hardy Temmink. - S.l. : s.n. - ISBN 9789461732309 - 163
afvalwaterbehandeling - geactiveerd slib - membranen - bioreactoren - filtratie - waste water treatment - activated sludge - membranes - bioreactors - filtration
Het doel van deze studie was te onderzoeken welke slibeigenschappen verantwoordelijk zijn voor de membraanvervuiling in MBR systemen, en om een methode te vinden om deze eigenschappen dusdanig te manipuleren dat de membraanvervuiling drastisch kan worden gereduceerd.
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.
Effect of temperature shocks on membrane fouling in membrane bioreactors
Brink, P. van den; Satpradit, O.A. ; Bentem, A. van; Zwijnenburg, A. ; Temmink, B.G. ; Loosdrecht, M.C.M. - \ 2011
Water Research 45 (2011)15. - ISSN 0043-1354 - p. 4491 - 4500.
afvalwaterbehandeling - bioreactoren - membranen - geactiveerd slib - temperatuur - vervuiling door afzetting - viscositeit - waste water treatment - bioreactors - membranes - activated sludge - temperature - fouling - viscosity - waste-water treatment - cross-flow microfiltration - flux-step method - activated-sludge - particle deposition - size distribution - light-scattering - bubble-size - performance - ultrafiltration
Temperature is known to influence the biological performance of conventional activated sludge systems. In membrane bioreactors (MBRs), temperature not only affects the bioconversion process but is also shown to have an effect on the membrane performance. Four phenomena are generally reported to explain the higher resistance for membrane filtration found at lower temperatures: (1) increased mixed liquor viscosity, reducing the shear stress generated by coarse bubbles, (2) intensified deflocculation, reducing biomass floc size and releasing EPS into the mixed liquor, (3) lower backtransport velocity and (4) reduced biodegradation of COD. Although the higher resistance at low temperatures has been reported in several papers, the relation with supernatant composition has not been investigated before. In this paper, the composition of the soluble fraction of the mixed liquor is related to membrane performance after exposing the sludge to temperature shocks. Flux step experiments were performed in an experimental system at 7, 15, and 25° Celsius with sludge that was continuously recirculated from a pilot-scale MBR. After correcting the permeate viscosity for temperature, higher membrane fouling rates were obtained for the lower temperature in combination with low fouling reversibility. The soluble fraction of the MBR mixed liquor was analysed for polysaccharides, proteins and submicron particle size distribution. At low temperature, a high polysaccharide concentration was found in the experimental system as compared to the MBR pilot. Upon decreasing the temperature of the mixed liquor, a shift was found in particle size towards smaller particles. These results show that the release of polysaccharides and/or submicron particles from sludge flocs could explain the increased membrane fouling at low temperatures
Operation of an aquatic worm reactor suitable for sludge reduction at large scale
Hendrickx, T.L.G. ; Elissen, H.J.H. ; Temmink, B.G. ; Buisman, C.J.N. - \ 2011
Water Research 45 (2011)16. - ISSN 0043-1354 - p. 4923 - 4929.
afvalwaterbehandeling - huishoudens - rioolslib - geactiveerd slib - bioreactoren - ontwerp - slibzuivering - aquatische wormen - oligochaeta - waste water treatment - households - sewage sludge - activated sludge - bioreactors - design - sludge treatment - aquatic worms - oligochaeta - eating waste sludge - activated-sludge
Treatment of domestic waste water results in the production of waste sludge, which requires costly further processing. A biological method to reduce the amount of waste sludge and its volume is treatment in an aquatic worm reactor. The potential of such a worm reactor with the oligochaete Lumbriculus variegatus has been shown at small scale. For scaling up purposes, a new configuration of the reactor was designed, in which the worms were positioned horizontally in the carrier material. This was tested in a continuous experiment of 8 weeks where it treated all the waste sludge from a lab-scale activated sludge process. The results showed a higher worm growth rate compared to previous experiments with the old configuration, whilst nutrient release was similar. The new configuration has a low footprint and allows for easy aeration and faeces collection, thereby making it suitable for full scale application.
Low dose powdered activated carbon addition at high sludge retention times to reduce fouling in membrane bioreactors
Remy, M.J.J. ; Marel, P. van der; Zwijnenburg, A. ; Rulkens, W.H. ; Temmink, B.G. - \ 2009
Water Research 43 (2009)2. - ISSN 0043-1354 - p. 345 - 350.
afvalwaterbehandeling - waterzuivering - geactiveerd slib - bioreactoren - membranen - biologische filtratie - actieve kool - doseringseffecten - zuiveringsinstallaties - waste water treatment - water treatment - activated sludge - bioreactors - membranes - biological filtration - activated carbon - dosage effects - purification plants - waste-water treatment - performance - filtration - mbr
The addition of a low concentration of PAC (0.5 g L-1 of sludge, i.e. a dose of 4 mg L-1 of wastewater), in combination with a relatively long SRT (50 days), to improve membrane filtration performance was investigated in two pilot-scale MBRs treating real municipal wastewater. Continuous filterability tests at high flux showed the possibility to run for 18 h at 72 L m-2 h-1 and 180 h at 50 L m-2 h-1, while significant fouling occurred without PAC. In addition, measurements of the critical flux showed an increase of 10% for this strategy. Low dosage and high retention time makes it feasible and cost effective. Further advantages with regard to permeate quality and possible micropollutants removal are currently under investigation.
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
Bioflocculation of mesophilic and thermophilic activated sludge
Vogelaar, J.C.T. ; Keizer, A. de; Spijker, S. ; Lettinga, G. - \ 2005
Water Research 39 (2005)1. - ISSN 0043-1354 - p. 37 - 46.
geactiveerd slib - afvalwaterbehandeling - biologische behandeling - temperatuur - uitvlokking - adsorptie - hydrofobiciteit - activated sludge - waste water treatment - biological treatment - temperature - flocculation - adsorption - hydrophobicity - paper-mill - water - effluent - temperatures - whitewater - reactors - flocs
Thermophilic activated sludge treatment is often hampered by a turbid effluent. Reasons for this phenomenon are so far unknown. Here, the hypothesis of the temperature dependency of the hydrophobic interaction as a possible cause for diminished thermophilic activated sludge bioflocculation was tested. Adsorption of wastewater colloidal particles was monitored on different flat surfaces as a function of temperature. Adsorption on a hydrophobic surface varied with temperature between 20 and 60 °C and no upward or downward trend could be observed. This makes the hydrophobic interaction hypothesis unlikely in explaining the differences in mesophilic and thermophilic activated sludge bioflocculation. Both mesophilic and thermophilic biomass did not flocculate with wastewater colloidal particles under anaerobic conditions. Only in the presence of oxygen, with biologically active bacteria, the differences in bioflocculation behavior became evident. Bioflocculation was shown only to occur with the combination of wastewater and viable mesophilic biomass at 30 °C, in the presence of oxygen. Bioflocculation did not occur in case the biomass was inactivated or when oxygen was absent. Thermophilic activated sludge hardly showed any bioflocculation, also under mesophilic conditions. Despite the differences in bioflocculation behavior, sludge hydrophobicity and sludge zetapotentials were almost similar. Theoretical calculations using the DLVO (Derjaguin, Landau, Verweij and Overbeek) theory showed that flocculation is unlikely in all cases due to long-range electrostatic forces. These calculations, combined with the fact that bioflocculation actually did occur at 30 °C and the unlikelyness of the hydrophobic interaction, point in the direction of bacterial exo-polymers governing bridging flocculation. Polymer interactions are not included in the DLVO theory and may vary as a function of temperature.
High-Rate Sulfate Reduction at High Salinity (up to 90 mS.cm-1) in Mesophilic UASB Reactors
Vallero, M.V.G. ; Sipma, J. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
Biotechnology and Bioengineering 86 (2004)2. - ISSN 0006-3592 - p. 226 - 235.
sulfaat - reductie - chemische reacties - zoutgehalte - geactiveerd slib - biodegradatie - acetaten - propionaten - ethanol - waterzuivering - sulfate - reduction - chemical reactions - salinity - activated sludge - biodegradation - acetates - propionates - ethanol - water treatment - desulfitobacterium-frappieri pcp-1 - anaerobic granular sludge - long-term competition - waste-water - methanogenic bacteria - biological treatment - reducing reactors - bed reactor - wastewaters - ammonia
Sulfate reduction in salt-rich wastewaters using unadapted granular sludge was investigated in 0.9 L UASB reactors (pH 7.0 ± 0.2; hydraulic retention time from 8-14 h) fed with acetate, propionate, or ethanol at organic loading rates up to 10 gCOD.L-1.day-1 and in excess sulfate (COD/SO of 0.5). High-rate sulfate reduction rates (up to 3.7 gSO42-.L-1.day-1) were achieved at salinities exceeding 50 gNaCl.L-1 and 1 gMgCl2.L-1. Sulfate reduction proceeded at a salinity of up to 70 gNaCl.L-1 and 1 gMgCl2.L-1 (corresponding to a conductivity of about 85-90 mS.cm-1), although at lower rates compared to a conductivity of 60-70 mS.cm-1. Ethanol as well as propionate were suitable substrates for sulfate reduction, with acetate and sulfide as the end products. The successful high-rate treatment was due to the proliferation of a halotolerant incomplete oxidizing SRB population present in the unadapted inoculum sludge. Bioaugmentation of this sludge with the acetate oxidizing halotolerant SRB Desulfobacter halotolerans was unsuccessful, as the strain washed out from the UASB reactor without colonizing the UASB granules. © 2004 Wiley Periodicals, Inc.
Fate of linear alkylbenzene sulfonate (LAS) in activated sludge plants
Temmink, B.G. ; Klapwijk, A. - \ 2004
Water Research 38 (2004)4. - ISSN 0043-1354 - p. 903 - 912.
afvalwaterbehandeling - oppervlaktespanningsverlagende stoffen - biodegradatie - monitoring - geactiveerd slib - zuiveringsinstallaties - waste water treatment - surfactants - biodegradation - monitoring - activated sludge - purification plants - waste-water treatment - surfactant monitoring program - biodegradation kinetics - environment - chemicals - behavior - culture - removal - sewage
Monitoring data were collected in a pilot-scale municipal activated sludge plant to assess the fate of the C12-homologue of linear alkyl benzene sulfonate (LAS-C12). The pilot-plant was operated at influent LAS-C12 concentrations between 2 and 12 mg/l and at sludge retention times of 10 and 27 days
Monitoring data were collected in a pilot-scale municipal activated sludge plant to assess the fate of the C-12-homologue of linear alkyl benzene sulfonate (LAS-C-12). The pilot-plant was operated at influent LAS-C-12 concentrations between 2 and 12 mg l(-1) and at sludge retention times of 10 and 27 days. Effluent and waste sludge concentrations varied between 5 and 10 mug l(-1) and between 37 and 69 mug g(-1) VSS, respectively. In the sludge samples only 2-8% was present as dissolved LAS-C-12, whereas the remaining 92-98% was found to be adsorbed to the sludge. In spite of this high degree of sorption, more than 99% of the LAS-C-12 load was removed by biodegradation, showing that not only the soluble fraction but also the adsorbed fraction of LAS-C-12 is readily available for biodegradation. Sorption and biodegradation of LAS-C-12 were also investigated separately. Sorption was an extremely fast and reversible process and could be described by a linear isotherm with a partition coefficient of 3.21 g(-1) volatile suspended solids. From the results of biodegradation kinetic tests it was concluded that primary biodegradation of LAS-C-12 cannot be described by a (growth) Monod model, but a secondary utilisation model should be used instead. The apparent affinity of the sludge to biodegrade LAS-C-12 increased when the sludge was loaded with higher influent concentrations of LAS-C-12. (C) 2003 Elsevier Ltd. All rights reserved.
Modelling anaerobic biomass growth kinetics with a substrate threshold concentration
Ribes, J. ; Keesman, K.J. ; Spanjers, H. - \ 2004
Water Research 38 (2004)20. - ISSN 0043-1354 - p. 4502 - 4510.
geactiveerd slib - afvalwaterbehandeling - biomassa - substraten - kinetica - modellen - activated sludge - waste water treatment - biomass - substrates - kinetics - models - activated-sludge - waste-water - continuous-culture - methanol - batch
Abstract Many bacteria have been observed to stop growing below a certain substrate threshold concentration. In this study, a modification of the Monod kinetics expression has been proposed to take into account this substrate threshold concentration observed in bacterial growth. Besides the threshold concentration no additional parameters have been added to the kinetic expression and so, only the substrate threshold concentration and the half-saturation constant have to be estimated for model calibration purposes. Furthermore, for parameter estimation purposes, practical identifiability of this new function has been studied and the results have been satisfactory. The new model has been applied, as an example, to a simple anaerobic model to simulate the competition for hydrogen between sulphate reducers and methanogens in a thermophilic methanol-fed bioreactor. Oscillatory behaviour and mathematical instabilities have been avoided by using the proposed model. Parameter sensitivities have also been calculated along the simulation period in order to investigate the importance of hydrogen threshold concentration parameters.
Sustainable sludge management : what are the challenges for the future?
Rulkens, W.H. - \ 2004
Water Science and Technology 49 (2004)10. - ISSN 0273-1223 - p. 11 - 19.
afvalwaterbehandeling - rioolslib - duurzaamheid (sustainability) - beoordeling - geactiveerd slib - recycling - fosfaten - stikstof - waste water treatment - sewage sludge - sustainability - assessment - activated sludge - recycling - phosphates - nitrogen - sewage-sludge - activated-sludge - anaerobic-digestion - disintegration - gasification - ozonation - recovery - quality
Sewage sludge is a serious problem due to the high treatment costs and the risks to environment and human health. Future sludge treatment will be progressively focused on an improved efficiency and environmental sustainability of the process. In this context a survey is given of the most relevant sludge treatment options and separate treatment steps. Special attention is paid to those processes that are simultaneously focused on the elimination of the risks for environment and human health and on the recovery or beneficial use of the valuable compounds in the sludge such as organic carbon compounds, inorganic non-toxic substances, phosphorus and nitrogen containing compounds. Also, a brief assessment is given of the specific future technological developments regarding the various treatment steps. Furthermore, it is discussed how to assess the various pathways which can lead to the required developments. In such an assessment the technical and economic feasibility, the environmental sustainability, the societal acceptance and the implementation route are important factors. The optimal approach also strongly depends on the local and regional situation of concern and the relevant current and future boundary conditions.
Forward and backward uncertainty propagation: an oxidation ditch modelling example
Abusam, A. ; Keesman, K.J. ; Straten, G. van - \ 2003
Water Research 37 (2003)2. - ISSN 0043-1354 - p. 429 - 435.
afvalwaterbehandeling - oxidatiesloten - simulatiemodellen - geactiveerd slib - onzekerheid - waste water treatment - oxidation ditches - simulation models - activated sludge - uncertainty - systems
In the field of water technology, forward uncertainty propagation is frequently used, whereas backward uncertainty propagation is rarely used. In forward uncertainty analysis, one moves from a given (or assumed) parameter subspace towards the corresponding distribution of the output or objective function. However, in the backward uncertainty propagation, one moves in the reverse direction, from the distribution function towards the parameter subspace. Backward uncertainty propagation, which is a generalisation of parameter estimation error analysis, gives information essential for designing experimental or monitoring programmes, and for tighter bounding of parameter uncertainty intervals. The procedure of carrying out backward uncertainty propagation is illustrated in this technical note by working example for an oxidation ditch wastewater treatment plant. Results obtained have demonstrated that essential information can be achieved by carrying out backward uncertainty propagation analysis
Kinetic comparisons of mesophilic and thermophilic aerobic biomass
Vogelaar, J.C.T. ; Klapwijk, A. ; Temmink, H. ; Lier, J.B. van - \ 2003
Journal of Industrial Microbiology and Biotechnology 30 (2003)2. - ISSN 1367-5435 - p. 81 - 90.
geactiveerd slib - biomassa - substraten - beluchting - respirometrie - kinetica - afvalwaterbehandeling - activated sludge - biomass - substrates - aeration - respirometry - kinetics - waste water treatment - waste-water treatment - soluble microbial products - community structure - olive oil - temperature - cultivation - reactors - removal - ihi-91 - death
Kinetic parameters describing growth and decay of mesophilic (30degreesC) and thermophilic (55degreesC) aerobic biomass were determined in continuous and batch experiments by using oxygen uptake rate measurements
Kinetic parameters describing growth and decay of mesophilic (30degreesC) and thermophilic (55degreesC) aerobic biomass were determined in continuous and batch experiments by using oxygen uptake rate measurements. Biomass was cultivated on a single soluble substrate (acetate) in a mineral medium. The intrinsic maximum growth rate (mu(max)) at 55degreesC was 0.71 +/- 0.09 h(-1), which is 1.5 times higher than the mu(max) at 30degreesC (0.48 +/- 0.11 h(-1)). The biomass decay rates increased from 0.004 h(-1) at 30degreesC to 0.017 h(-1) at 55degreesC. Monod constants were very low for both types of biomass: 9 +/- 2 mg chemical oxygen demand (COD) 1(-1)at 30degreesC and 3 +/- 2mg COD 1(-1)at 55degreesC. Theoretical biomass yields were similar at 30 and 55degreesC: 0.5 g biomass COD (g acetate COD)(-1). The observed biomass yields decreased under both temperature conditions as a function of the cell residence ti(m)e. Under thermophilic conditions, this effect was more pronounced due to the higher decay rates, resulting in lower biomass production at 55degreesC compared to 30degreesC.
A new method study biodegradation kinetics of anorganic trace pollutants by activated sludge
Temmink, H. ; Klapwijk, A. - \ 2003
Chemosphere 52 (2003)1. - ISSN 0045-6535 - p. 221 - 229.
geactiveerd slib - verontreinigende stoffen - biodegradatie - afvalwaterbehandeling - activated sludge - pollutants - biodegradation - waste water treatment - waste-water treatment - linear alkylbenzene sulfonate - fate - parameters - bacteria - growth - model - las
A reliable prediction of the behaviour of organic trace compounds in activated sludge plants requires an accurate input of the biodegradation kinetics. Often these kinetics are extrapolated from the results of standardised biodegradation tests. However, these tests generally are not designed to yield kinetic information and do not reflect the conditions in activated sludge plants. To overcome these problems a new test method was developed which is referred to as a ‘by-pass’ test. The test methodology is explained and examples are given for three compounds: the C12-homologue of linear alkylbenzene sulfonate, nitrilotriacetic acid and toluene. More experience with the test is required, particularly with respect to selection of the proper test settings, which are compound related. The test is a suitable tool in a research environment, for example to investigate the effect of plant operational parameters on the biodegradation kinetics.
|Terugwinning van fosfaat uit huishoudelijk afvalwater als grondstof voor de fosfaatindustrie: mogelijkheden, knelpunten van verder onderzoek
Temmink, B.G. ; Top, F. ; Roosma, A. ; Steinbusch, K. ; Hendriks, G. ; Klapwijk, A. ; Schipper, W. - \ 2002
Afvalwaterwetenschap 1 (2002)3. - ISSN 1568-3788 - p. 10 - 10.
afvalwaterbehandeling - biologische behandeling - fosfor - verwijdering - geactiveerd slib - afvalwater - fosfaten - recycling - haalbaarheidsstudies - waste water treatment - biological treatment - phosphorus - removal - activated sludge - waste water - phosphates - feasibility studies
Alhoewel terugwinning van fosfaat uit huishoudelijk afvalwater technisch zeer goed mogelijk is, zijn de kosten vele malen hoger dan de huidige prijs van het fosfaaterts. Een alternatieve en mogelijk goedkopere techniek is aluminiumprecipitatie van fosfaat uit de fosfaat-rijke waterstroom die bij biologische defosfatering ontstaat
Korrelvorming onder denitrificerende omstandigheden : achtergronden, mogelijkheden en economische aspecten
Temmink, B.G. ; Boncz, M.A. - \ 2002
Utrecht : Stowa (STOWA rapport W03) - ISBN 9789057731976 - 26
afvalwaterbehandeling - slib - denitrificatie - geactiveerd slib - haalbaarheidsstudies - kosten - huishoudens - zuiveringsinstallaties - waste water treatment - sludges - denitrification - activated sludge - feasibility studies - costs - households - purification plants
Sensitivity analysis of the secondary settling tank double-exponential function model
Abusam, A. ; Keesman, K.J. - \ 2002
European water management : official publication of the European Water Pollution Control Association 2002 (2002)7. - ISSN 1461-6971
afvalwaterbehandeling - geactiveerd slib - afvoerwater - waterkwaliteit - vloeistofmechanica - modellen - zuiveringsinstallaties - waste water treatment - activated sludge - effluents - water quality - fluid mechanics - models - purification plants
The secondary settling tank plays a very crucial role in achieving the very strict effluent standards of wastewater treatment plants. To investigate the ability of the widely used secondary settling tank model, the double-exponential model, to predict the dynamic behavior, a factorial sensitivity analysis was carried out
Respirometry-based on-line model parameter estimation at a full-scale WWTP
Spanjers, H. ; Patry, G.G. ; Keesman, K.J. - \ 2002
Water Science and Technology 45 (2002). - ISSN 0273-1223 - p. 4 - 5.
afvalwaterbehandeling - geactiveerd slib - respirometrie - meting - modellen - rioolwater - chemisch zuurstofverbruik - waste water treatment - activated sludge - respirometry - measurement - models - sewage - chemical oxygen demand
This paper describes part of a project to develop a systematic approach to knowledge extraction from on-line respirometric measurements in support of wastewater treatment plant control and operation. The paper deals with the following issues: (1) test of the implementation of an automatic set-up consisting of a continuous laboratory respirometer integrated in a mobile trailer with sampling and dosing equipment, and data-acquisition and communication system; (2) assessment of activated sludge/sewage characteristics from sludge respirograms by model parameter estimation; (3) comparison of the parameter estimates with regular plant data and information obtained from supplementary wastewater respirograms. The paper describes the equipment and some of its measuring results from a period of one week at a large-scale wastewater treatment plant. The measurements were evaluated in terms of the common activated sludge modelling practice. The automatic set-up allowed reliable measurements during at least one week. The data were used to calibrate two different version of the model, and independent parameter estimates were obtained.
Estimation of uncertainties in the performance indices of an oxidation ditch benchmark
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van; Meinema, K. - \ 2002
Journal of Chemical Technology and Biotechnology 77 (2002). - ISSN 0268-2575 - p. 1058 - 1067.
afvalwater - afvalwaterbehandeling - geactiveerd slib - oxidatiesloten - modellen - onzekerheid - analyse - prestatieniveau - waste water - waste water treatment - activated sludge - oxidation ditches - models - uncertainty - analysis - performance
Estimation of the influence of different sources of uncertainty is very important in obtaining a thorough evaluation or a fair comparison of the various control strategies proposed for wastewater treatment plants. This paper illustrates, using real data obtained from a full-scale oxidation ditch wastewater treatment plant, how the effect of the various uncertainty sources can be quantified. A Monte Carlo simulation analysis method was preferred over a first-order variance analysis method because it is more reliable and it provides the complete probability distribution. For various sources of uncertainty, except for the additive modelling error, samples were selected using the efficient Latin Hypercube Sampling technique. Large deviations in the benchmark performance indices from the nominal values, due to uncertainty in influent loads and parameter values, were found, in particular, for effluent quality and total sludge production indices. However, relatively smaller deviations are found due to uncertainty in the states' initial conditions. The effect of the model structural uncertainty on the performance indices was found to be negligible. ? 2002 Society of Chemical Industry.