Harvesting and cell disruption of microalgae
Lam, Gerard Pieter 't - \ 2017
Wageningen University. Promotor(en): R.H. Wijffels; M.H.M. Eppink, co-promotor(en): M.H. Vermuë. - Wageningen : Wageningen University - ISBN 9789463431736 - 206
algae - harvesting - flocculation - polymers - chlorella vulgaris - biorefinery - electric field - organelles - algen - oogsten - uitvlokking - polymeren - chlorella vulgaris - bioraffinage - elektrisch veld - organellen
Microalgae are a potential feedstock for various products. At the moment, they are already used as feedstock for high-valuable products (e.g. aquaculture and pigments).
Microalgae pre-dominantly consist out of proteins, lipids and carbohydrates. This makes algae an interesting feedstock for various bulk-commodities. To successfully produce bulk-commodities, a multi-product biorefinery should be adopted that aims on production of both bulk- and high value co-products. In the downstream process, however, harvesting- and cell disruption are technological hurdles for cost effective multi-product biorefinery.
Flocculation is considered as a low-cost harvesting process. Flocculating microalgae at high salinities used to be not feasible We demonstrated that marine microalgae can successfully be flocculated and harvested by using cationic polymers.
In the second part of this thesis we studied Pulsed Electric Field (PEF) as potential cheap and non-disruptive technology to open microalgae. PEF-treatment evokes openings/’holes’ in micro-organisms. PEF in combination with a pre-treatment to weaken the cell wall resulted in release of proteins from microalgae at low energy consumption.
Recent advances in technology development learned that harvesting of micro-algae is no longer a bottleneck. Future research and development should focus on cell disruption and mild extraction technologies. Costs for the biorefinery will decrease by process simplification. For that unit operations for cell disruption and extraction need to be integrated.
This project was part of a large public private partnership program AlgaePARC biorefinery (www.AlgaePARC.com). Objective of this program is to develop a more sustainable and economically feasible microalgae production process. For that all biomass components (e.g. proteins, lipids, carbohydrates) should be used at minimal energy requirements and minimal costs while keeping the functionality of the different biomass components. Biorefining of microalgae is very important for the selective separation and use of the different functional biomass components.
Ternary supramolecular quantum-dot network flocculation for selective lectin detection
Oikonomou, Maria ; Wang, Junyou ; Carvalho, Rui Rijo ; Velders, Aldrik H. - \ 2016
Nano Research 9 (2016)7. - ISSN 1998-0124 - p. 1904 - 1912.
cyclodextrin - flocculation - lectin - quantum dot - sensor - supramolecular
We present a versatile, tuneable, and selective nanoparticle-based lectin biosensor, based on flocculation of ternary supramolecular nanoparticle networks (NPN), formed through the sequential binding of three building blocks. The three building blocks are β-cyclodextrin-capped CdTe quantum dots, tetraethylene glycol-tethered mannose-adamantane cross-linkers (ADTEGMan), and the tetravalent lectin Concanavalin A (ConA). The working principle of this selective sensor lies in the dual orthogonal molecular interactions of the linker, uniting adamantane-β-cyclodextrin and mannose-lectin interaction motifs, respectively. Only when the lectin is present, sequential binding takes place, leading to in situ self-organization of the sensor through the formation of ternary supramolecular networks. Monitoring the loss of fluorescence signal of the quantum dots in solution, caused by controlled network formation and consecutive flocculation and sedimentation, leads to selective, qualitative, and quantitative lectin detection. Fluorescent sedimented networks can be observed by the naked eye or under UV illumination for a lectin concentration of up to 10−8 M. Quantitative detection is possible at 100 min with a lower detection limit of approximately 5 × 10−8 M.[Figure not available: see fulltext.]
Properties of Oil/Water Emulsions Affecting the Deposition, Clearance and After-Feel Sensory Perception of Oral Coatings
Camacho, S. ; Hollander, E.L. de; Velde, E. van de; Stieger, M.A. - \ 2015
Journal of Agricultural and Food Chemistry 63 (2015)8. - ISSN 0021-8561 - p. 2145 - 2153.
in-water emulsions - flavor perception - sodium caseinate - oil content - viscosity - flocculation - saliva - tongue - retention - behavior
The aims of this study were to investigate the influence of (i) protein type, (ii) protein content, and (iii) viscosity of o/w emulsions on the deposition and clearance of oral oil coatings and after-feel perception. Oil fraction (moil/cm2tongue) and after-feel perception differed considerably between emulsions which do not flocculate under in mouth conditions (Na-caseinate) and emulsions which flocculate under in mouth conditions (lysozyme). The irreversible flocculation of lysozyme stabilized emulsions caused slower oil clearance from the tongue surface compared to emulsions stabilized with Na-caseinate. Protein content had a negative relation with oil fraction for lysozyme stabilized emulsions and no relation for Na-caseinate stabilized emulsions immediately after expectoration. Viscosity differences did not affect oil fraction, although the presence of thickener decreased deposition of oil on tongue. We conclude that after-feel perception of o/w emulsions is complex and depends on the deposited oil fraction, the behavior of proteins in mouth, and thickeners.
Salt stress in a membrane bioreactor: Dynamics of sludge properties, membrane fouling and remediation through powdered activated carbon dosing
Temmerman, L. De; Maere, T. ; Temmink, H. ; Zwijnenburg, A. ; Nopens, I. - \ 2014
Water Research 63 (2014). - ISSN 0043-1354 - p. 112 - 124.
waste-water treatment - organic-matter - energy-consumption - high salinity - mbr - filterability - ultrafiltration - flocculation - temperature - mechanisms
Membrane bioreactors are a well-established technology for wastewater treatment. However, their efficiency is adversely impacted by membrane fouling, primarily inciting very conservative operations of installations that makes them less appealing from an economic perspective. This fouling propensity of the activated sludge is closely related to system disturbances. Therefore, improved insight into the impact of fouling is crucial towards increased membrane performance. In this work, the disturbance of a salt shock was investigated with respect to sludge composition and filterability in two parallel lab-scale membrane bioreactors. Several key sludge parameters (soluble microbial products, sludge-bound extracellular polymeric substances, supramicron particle size distributions (PSD), submicron particle concentrations) were intensively monitored prior to, during, and after a disturbance to investigate its impact as well as the potential governing mechanism. Upon salt addition, the supramicron PSD immediately shifted to smaller floc sizes, and the total fouling rate increased. Following a certain delay, an increase in submicron particles, supernatant proteins, and polysaccharides was observed as well as an increase in the irreversible membrane fouling rate. Recovery from the disturbance was evidenced with a simultaneous decrease in the above mentioned quantities. A similar experiment introducing powdered activated carbon (PAC) addition used for remediation resulted in either no or less significant changes in the above mentioned quantities, signifying its potential as a mitigation strategy. (C) 2014 Elsevier Ltd. All rights reserved.
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
Improved emulsion stability by succinylation of patatin is caused by partial unfolding rather than charge effects
Delahaije, R.J.B.M. ; Wierenga, P.A. ; Giuseppin, M.L.F. ; Gruppen, H. - \ 2014
Journal of Colloid and Interface Science 430 (2014). - ISSN 0021-9797 - p. 69 - 77.
in-water emulsions - protein-exposed hydrophobicity - beta-lactoglobulin - drop size - adsorption - flocculation - interface - stabilization - ph - dependence
This study investigates the influence of succinylation on the molecular properties (i.e. charge, structure and hydrophobicity) and the flocculation behavior of patatin-stabilized oil-in-water emulsions. Patatin was succinylated to five degrees (0% (R0) to 57% (R2.5)). Succinylation not only resulted in a change of the protein charge but also in (partial) unfolding of the secondary structure, and consequently in an increased initial adsorption rate of the protein to the oil–water interface. The stability against salt-induced flocculation showed two distinct regimes, instead of a gradual shift in stability as expected by the DLVO theory. While flocculation was observed at ionic strengths > 30 mM for the emulsions stabilized by the variants with the lowest degrees of modification (R0–R1), the other variants (R1.5–R2.5) were stable against flocculation ¿ 200 mM. This was related to the increased initial adsorption rate, and the consequent transition from a protein-poor to a protein-rich regime. This was confirmed by the addition of excess protein to the emulsions stabilized by R0–R1 which resulted in stability against salt-induced flocculation. Therefore, succinylation of patatin indirectly results in stability against salt-induced flocculation, by increasing the initial adsorption rate of the protein to the oil–water interface, leading to a shift to the protein-rich regime.
A model-based combinatorial optimisation approach for energy-efficient processing of microalgae
Slegers, P.M. ; Koetzier, B.J. ; Fasaei, F. ; Wijffels, R.H. ; Straten, G. van; Boxtel, A.J.B. van - \ 2014
Algal Research 5 (2014). - ISSN 2211-9264 - p. 140 - 157.
response-surface methodology - life-cycle assessment - biodiesel production - algal biomass - process integration - transesterification - oil - flocculation - biorefinery - extraction
The analyses of algae biorefinery performance are commonly based on fixed performance data for each processing step. In this work, we demonstrate a model-based combinatorial approach to derive the design-specific upstream energy consumption and biodiesel yield in the production of biodiesel from microalgae. Process models based on mass and energy balances and conversion relationships are presented for several possible process units in the algae processing train. They allow incorporating the effects of throughput capacity and process conditions, which is not possible in the data-based approach. Therefore, the effect of choices in the design on the overall performance can be quantified. The process models are organised in a superstructure to evaluate all combinations of routings. First, this is done for selected fixed design conditions, which is followed by optimisation of the process conditions for each route by maximising the net energy ratio (NER), based on upstream energy consumption and biodiesel yield. A scenario based on current energy production and state-of-the art techniques for algae processing is considered. The optimised process conditions yield NER values which are up to about 30% higher than those for fixed process conditions. In addition, the approach allows a quantitative bottleneck analysis for each process route. The model-based approach proves to be a versatile tool to guide the design of efficient microalgae processing systems.
Effect of dissolved oxygen concentration on the bioflocculation process in high loaded MBRs
Faust, L. ; Temmink, B.G. ; Zwijnenburg, A. ; Kemperman, A.J.B. ; Rijnaarts, H. - \ 2014
Water Research 66 (2014). - ISSN 0043-1354 - p. 199 - 207.
afvalwaterbehandeling - uitvlokking - bioreactoren - waste water treatment - flocculation - bioreactors - waste-water treatment - extracellular polymeric substances - activated-sludge flocs - improved energy recovery - membrane bioreactor - size distribution - biofilm structure - stability - sewage - performance
High-loaded membrane bioreactors (HL-MBRs), i.e. MBRs which are operated at extremely short sludge and hydraulic retention times, can be applied to flocculate and concentrate sewage organic matter. The concentrated organics can be used for energy recovery, or for the production of more valuable organic chemicals. Little is known about the effect of the dissolved oxygen concentration (DO) on this bioflocculation process. To examine this effect, two HL-MBRs were operated, respectively at a low (1 mg L-1) and a higher (4 mg L-1) DO. The higher DO resulted in a better flocculation efficiency, i.e. 92% of the colloidal COD in the sewage flocculated compared to 69% at the lower DO. The difference was attributed to a higher microbial production of extracellular polymeric substances at a DO of 4 mg L-1 and to more multivalent cations (calcium, iron and aluminium) being distributed to the floc matrix. In addition, the HL-MBR that was operated at a DO of 4 mg L-1 gave a bigger mean floc size, a lower supernatant turbidity, better settleability and better membrane filterability than the HL-MBR that was operated at a DO of 1 mg L-1.
Mechanism behind autoflocculation of unicellular green microalgae
Salim, S. ; Kosterink, N. ; Tchetkoua Wacka, N.D. ; Vermue, M.H. ; Wijffels, R.H. - \ 2014
Journal of Biotechnology 174 (2014). - ISSN 0168-1656 - p. 34 - 38.
algogenic organic-matter - flocculation - diatoms
The oleaginous Ettlia texensis is an autoflocculating green microalga that can be used for bio-flocculation of other microalgae species to facilitate harvesting. In this study the mechanism behind autoflocculation of E. texensis was revealed by scanning electron microscopy (SEM) analysis and by characterisation of the cell surface properties. SEM analysis and measurement of extracellular polymeric substances (EPS) showed that autoflocculation of E. texensis is due to the EPS containing mainly glycoproteins patched to the cell surface. Despite the presence of charged groups on the cell surface, they do not seem to attribute to autoflocculation of E. texensis. During bio-flocculation of E. texensis with Chlorella vulgaris EPS structures between both microalgal species were observed. EPS thus not only play a predominant role in autoflocculation of E. texensis but also in bio-flocculation when using this microalga to harvest others.
Controlling eutrophication by combined bloom precipitation and sediment phosphorus inactivation
Lürling, M.F.L.L.W. ; Oosterhout, J.F.X. - \ 2013
Water Research 47 (2013)17. - ISSN 0043-1354 - p. 6527 - 6537.
meren - oppervlaktewaterkwaliteit - eutrofiëring - cyanobacteriën - sedimentatie - uitvlokking - lanthaan - bentoniet - tests - fosfor - ecologisch herstel - noord-brabant - lakes - surface water quality - eutrophication - cyanobacteria - sedimentation - flocculation - lanthanum - bentonite - tests - phosphorus - ecological restoration - noord-brabant - prymnesium-parvum haptophyceae - harmful cyanobacterial blooms - dissolved organic-matter - rare-earth-elements - of-the-art - microcystis-aeruginosa - lake restoration - local soils - polyaluminum chloride - phosphate adsorption
The hypothesis that the combination of the flocculent polyaluminium chloride (PAC) with the lanthanum-modified bentonite Phoslock® (Flock & Lock) could sink effectively a water bloom of cyanobacteria and could shift a turbid, cyanobacteria infested lake to a clear water lake was tested in a controlled laboratory experiment and a whole lake experiment. In the laboratory, a relatively low dose of the flocculent PAC (2.2 and 4.4 mg Al l-1) was insufficient to sediment positively buoyant cyanobacteria (Microcystis aeruginosa). Similarly, the lanthanum modified clay (dosed at 390 mg l-1) was insufficient to sediment the positively buoyant cyanobacteria. However, the combination of PAC and Phoslock® effectively sedimented cyanobacteria flocks. Likewise, a combined treatment of 2 tons PAC and 18 tons Phoslock® in Lake Rauwbraken in April 2008 effectively sedimented a developing cyanobacteria bloom of Aphanizomenon flos-aquae. The average chlorophyll-a concentration in the two years prior to this Flock & Lock treatment was 19.5 (±36.5) µg l-1, while it was as low as 3.7 (±4.5) µg l-1 in the years following the treatment. The combined treatment effectively reduced the amount of total phosphorus (TP) in the water column from on average 169 (±126) µg P l-1 before the application to 14 (±15) µg P l-1 after the treatment. Based on mean summer chlorophyll-a and TP concentrations, the lake was shifted from a eutrophic/hypertrophic state to an oligo/mesotrophic state. From directly after treatment in April 2008 until and including 2013, Lake Rauwbraken remained in an oligo-mesotrophic clear water state with TP reduced to less than 10% of the pre-treatment. This result shows that eutrophication in relatively small, isolated, stratifying lakes can be restored by targeting both water column and sediment P using a combination of flocculent and solid phase P-sorbent
Effect of growth phase on harvesting characteristics, autoflocculation and lipid content of Ettlia texensis for microalgal biodiesel production
Salim, S. ; Shi, Z. ; Vermuë, M.H. ; Wijffels, R.H. - \ 2013
Bioresource Technology 138 (2013). - ISSN 0960-8524 - p. 214 - 221.
flocculation - accumulation - coagulation - efficiency - economics - biomass
The effect of growth phase on the recovery of the autoflocculating microalgae Ettlia texensis was studied. In the stationary phase, 90% recovery was achieved after 3 h settling. Scanning electron microscopic pictures revealed that extracellular polymeric substances (EPS) on the cell surface were involved in autoflocculation. During the stationary phase an increase of the protein fraction in the EPS was observed while the total fatty acids content increased. The autoflocculating properties of E. texensis combined with favourite fatty acid content and composition make this microalgae an excellent candidate for biodiesel production if harvested at the end of the stationary phase.
Algenoogst 100 keer energiezuiniger
Salim, Sina - \ 2013
algae - algae culture - harvesting - flocculation - energy saving - biobased economy
Harvesting microalgae by bio-flocculation and autoflocculation
Salim, S. - \ 2013
Wageningen University. Promotor(en): Rene Wijffels, co-promotor(en): Marian Vermue. - S.l. : s.n. - ISBN 9789461736710 - 152
algen - oogsten - uitvlokking - bioproceskunde - biodiesel - biomassa productie - biobased economy - algenteelt - algae - harvesting - flocculation - bioprocess engineering - biodiesel - biomass production - biobased economy - algae culture
Harvesting in commercial microalgae production plants is generally done by centrifugation, but this requires upto about 50% of the total energy gained from the microalgae. The energy needed for harvesting can be reduced considerably by pre-concentration of the microalgae prior to further dewatering. The focus of this thesis was on development of a controlled pre-concentration step in which bio-flocculation and autoflocculation using oleaginous microalgae is applied combined with gravity sedimentation. This technology was evaluated in terms of energy demand for harvesting microalgae.
Emulsion properties of algae soluble protein isolate from Tetraselmis sp.
Schwenzfeier, A. ; Helbig, A. ; Wierenga, P.A. ; Gruppen, H. - \ 2013
Food Hydrocolloids 30 (2013)1. - ISSN 0268-005X - p. 258 - 263.
in-water emulsions - diffusing wave spectroscopy - whey-protein - physicochemical properties - stabilized emulsions - flocculation - emulsifiers - adsorption - microalgae - pectin
To study possible applications of microalgae proteins in foods, a colourless, protein-rich fraction was isolated from Tetraselmis sp. In the present study the emulsion properties of this algae soluble protein isolate (ASPI) were investigated. Droplet size and droplet aggregation of ASPI stabilized oil-in-water emulsions were studied as function of isolate concentration (1.25–10.00 mg/mL), pH (3–7), and ionic strength (NaCl 10–500 mM; CaCl2 0–50 mM). Whey protein isolate (WPI) and gum arabic (GA) were used as reference emulsifiers. The lowest isolate concentrations needed to reach d32 = 1 µm in 30% oil-in-water emulsions were comparable for ASPI (6 mg/mL) and WPI (4 mg/mL). In contrast to WPI stabilized emulsions ASPI stabilized emulsions were stable around pH 5 at low ionic strength (I = 10 mM). Flocculation only occurred around pH 3, the pH with the smallest net droplet ¿-potential. Due to the charge contribution of the anionic polysaccharide fraction present in ASPI its droplet ¿-potential remained negative over the whole pH range investigated. An increase in ionic strength (=100 mM) led to a broadening of the pH range over which the ASPI stabilized emulsions were unstable. GA emulsions are not prone to droplet aggregation upon changes in pH or ionic strength, but much higher concentrations are needed to produce stable emulsions. Since ASPI allows the formation of stable emulsions in the pH range 5–7 at low protein concentrations, it can offer an efficient natural alternative to existing protein–polysaccharide complexes.
Mineralenconcentraten uit dierlijke mest = Mineral concentrates from animal slurry
Hoeksma, P. ; Buisonjé, F.E. de - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 626) - 23
dierlijke meststoffen - mineralen - polyacrylamide - mestverwerking - uitvlokking - flotatie - centrifuges - animal manures - minerals - polyacrylamide - manure treatment - flocculation - flotation - centrifuges
In 2011 6 pilot production plants of mineral concentrates from animal manure were monitored, with the aim of gathering additional data on the chemical composition of the raw slurry and the end products. Beside that a literature review was executed to reveal the biological degradability of polyacrylamides which are used as additives in the production process. Furthermore two ways to upgrade the mineral concentrate were investigated.
Algen werkpaarden van de biobased economy
Lamers, Packo - \ 2011
algae - algae culture - cropping systems - biobased economy - biomass - biomass production - economic viability - flocculation - biorefinery
Combinatorial Life Cycle Assessment to Inform Process Design of Industrial Production of Algal Biodiesel
Brentner, L.B. ; Eckelman, M.J. ; Zimmerman, J.B. - \ 2011
Environmental Science and Technology 45 (2011). - ISSN 0013-936X - p. 7060 - 7067.
supercritical co2 - microalgae - bioreactors - extraction - chitosan - energy - gas - photobioreactors - flocculation - cultivation
The use of algae as a feedstock for biodiesel production is a rapidly growing industry, in the United States and globally. A life cycle assessment (LCA) is presented that compares various methods, either proposed or under development, for algal biodiesel to inform the most promising pathways for sustainable full-scale production. For this analysis, the system is divided into five distinct process steps: (1) microalgae cultivation, (2) harvesting and/or dewatering, (3) lipid extraction, (4) conversion (transesterification) into biodiesel, and (5) byproduct management. A number of technology options are considered for each process step and various technology combinations are assessed for their life cycle environmental impacts. The optimal option for each process step is selected yielding a best case scenario, comprised of a flat panel enclosed photobioreactor and direct transesterification of algal cells with supercritical methanol. For a functional unit of 10 GJ biodiesel, the best case production system yields a cumulative energy demand savings of more than 65 GJ, reduces water consumption by 585 m3 and decreases greenhouse gas emissions by 86% compared to a base case scenario typical of early industrial practices, highlighting the importance of technological innovation in algae processing and providing guidance on promising production pathways.
Textural perception of liquid emulsions: Role of oil content, oil viscosity and emulsion viscosity
Aken, G.A. van; Vingerhoeds, M.H. ; Wijk, R.A. de - \ 2011
Food Hydrocolloids 25 (2011)4. - ISSN 0268-005X - p. 789 - 796.
in-water emulsions - sensory perception - stabilized emulsions - oral conditions - food emulsions - saliva - flocculation - polysaccharide - dispersions - creaminess
This work describes a study on the in-mouth textural perception of thickened liquid oil-in-water emulsions. The variables studied are oil content, oil viscosity, and the concentration of polysaccharide thickener. Gum arabic was chosen as the thickener because of the nearly Newtonian behavior of its solutions and special care was taken to suppress aroma clues. Based on the experimental results and findings from previous studies, this work shows that the emulsion droplets influence textural sensory perception of liquid emulsions by three main mechanisms, each of which relate to changes in specific sensory attributes, and none of which were found to be significantly dependent on the viscosity of the oil: 1) by increasing the viscosity, 2) by becoming incorporated in the mucous oral coating, and 3) by spreading oil at the oral surfaces. Based on these results, the possibility for replacement of emulsified fat by a polysaccharide thickener is evaluated.
Removal of micropollutants from grey water : combining biological and physical/chemical processes
Hernandez Leal, L. - \ 2010
Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Grietje Zeeman; Hardy Temmink. - [S.l. : S.n. - ISBN 9789085857013 - 181
afvalwaterbehandeling - verontreinigende stoffen - biodegradatie - anaërobe afbraak - biochemisch zuurstofverbruik - chemisch zuurstofverbruik - uitvlokking - desinfectie - nieuwe sanitatie - waste water treatment - pollutants - biodegradation - anaerobic digestion - biochemical oxygen demand - chemical oxygen demand - flocculation - disinfection - new sanitation
Grey water consists of the discharges from kitchen sinks, showers, baths, washing machines and hand basins. The amount of grey water produced per person in The Netherlands is about 90 Ld-1, accounting for up to 75 % of the wastewater volume produced by households, and over 90 % if vacuum toilets are installed. Grey water is relatively low in pollution and therefore, after appropriate treatment, has great potential for reuse in non-potable applications such as infiltration, irrigation, toilet flushing, laundry water, etc. The goal of this thesis was to develop a treatment concept for grey water to exploit its reuse potential. A special focus of this thesis was set on the study of organic micropollutants from personal care and household chemicals. Grey water (from 32 houses in Sneek, The Netherlands) contains, on average, 724-150 mgL-1 of chemical oxygen demand (COD), 27-12 mgL-1 of total nitrogen, 7.2-4.2 mgL-1 of phosphorus and 41-12 mgL-1 of anionic surfactants. The high biodegradability of grey water (70-5 %) indicated the possibility of recovering COD as methane. Biological treatment of grey water was conducted in three systems, aerobic, anaerobic and combined anaerobic + aerobic, at a total hydraulic retention time (HRT) of 12-13 hours at 32 °C. Aerobic treatment in a sequencing batch reactor resulted in COD removal of 90 %, which was significantly higher than 51 % removal by anaerobic treatment in an upflow anaerobic sludge blanket (UASB) reactor. Grey water treatment in a combined anaerobic + aerobic system resulted in a COD removal efficiency of 89 %. The application of a UASB reactor for the pre-treatment of grey water yielded a small amount of energy. Therefore, the aerobic system was preferred for grey water treatment. Bioflocculation of grey water in a high loaded membrane bioreactor was tested as alternative to aerobic treatment. The concentrated grey water of this process can potentially increase the methane yield by 73 % within ‘new sanitation' concepts. Eighteen compounds of personal care products and household chemicals (UV- filters, fragrances, preservatives, biocides, surfactants) were measured in grey water at low gL-1 levels. During biological treatment most of these compounds were partially removed. In general, the treatment in the aerobic system lead to the highest removal efficiencies of these compounds, where biodegradation and adsorption to sludge were the most likely removal mechanisms. However, the UV-filters PBSA and EHMC and the fragrance tonalide were poorly removed in the tested biological systems. Although reuse standards for these compounds do not exist, the post-reatment of aerobically treated effluent was recommended prior to reuse. Adsorption on activated carbon and ozonation were proven effective as post-treatment options for grey water.
Why low powdered activated carbon addition reduces membrane fouling in MBRs
Remy, M.J.J. ; Potier, V. ; Temmink, B.G. ; Rulkens, W.H. - \ 2010
Water Research 44 (2010)3. - ISSN 0043-1354 - p. 861 - 867.
afvalwaterbehandeling - waterzuivering - actieve kool - adsorptie - membranen - biologische filtratie - filtreerbaarheid - uitvlokking - biodegradatie - zuiveringsinstallaties - waste water treatment - water treatment - activated carbon - adsorption - membranes - biological filtration - filterability - flocculation - biodegradation - purification plants - waste-water treatment - bioreactor mbr - sludge - flux - performance - filtration - bioflocculation - operation
Previous research had demonstrated that powdered activated carbon (PAC), when applied at very low dosages and long SRTs, reduces membrane fouling in membrane bioreactor (MBRs). In this contribution several mechanisms to explain this beneficial effect of PAC were investigated, including enhanced scouring of the membrane surface by PAC particles, adsorption of membrane foulants by PAC and subsequent biodegradation and a positive effect of PAC on the strength of the sludge flocs. It was concluded that the latter mechanism best explains why low dosages of PAC significantly reduce membrane fouling. Cheaper alternatives for PAC may have a similar effect