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Recep Kaan Dereli - One of the best experts on this subject based on the ideXlab platform.

  • biological performance and sludge Filterability of anaerobic membrane bioreactors under nitrogen limited and supplied conditions
    Water Research, 2018
    Co-Authors: Recep Kaan Dereli, Xiaofei Wang, Frank P Van Der Zee, Jules B Van Lier
    Abstract:

    Abstract The impact of nitrogen on biological performance and sludge Filterability of anaerobic membrane bioreactors was investigated in two lab-scale cross-flow anaerobic membrane bioreactors that were fed with cheese whey at two different COD:TKN ratios (50 and 190). Nitrogen deprivation adversely affected the biological treatment performance and reactor stability, as indicated by volatile fatty acids accumulation. On the other hand, nitrogen (urea) supplementation resulted in a reduced sludge median particle size and decreased sludge Filterability. Standard Filterability parameters such as capillary suction time and specific resistance to filtration tended to rapidly increase in the nitrogen supplemented reactor. The critical fluxes in the nitrogen limited and supplemented reactors were 20 and 9 L m−2 h−1, respectively. The rapid deterioration of sludge Filterability under nitrogen supplemented conditions was attributed to abundant growth of dispersed biomass. Thus, the COD:TKN ratio of wastewater affected both bioconversion and Filterability performance in the anaerobic membrane bioreactors.

  • a systematic study on the effect of substrate acidification degree and acidogenic biomass on sludge Filterability
    Water Research, 2015
    Co-Authors: Recep Kaan Dereli, Frank P Van Der Zee, Lefki Loverdou, Jules B Van Lier
    Abstract:

    The influence of substrate acidification on sludge filtration characteristics was systematically investigated by using short term filtration tests. Four reactors were operated with raw and acidified whey permeate in order to evaluate the effect of acidogens on sludge Filterability. The results showed that feeding non-acidified substrate promoted the growth of acidogens which in return decreased the median particle size of the sludge and adversely influenced specific resistance to filtration (SRF). In addition to the presence of acidogens, the food to mass (F:M) ratio was found as an important operation parameter on sludge Filterability. Various Filterability indicators, such as capillary suction time (CST), SRF and supernatant Filterability, tended to became worse at increased F:M ratios. The decreased Filterability at high F:M ratio was attributed to the accumulation of soluble microbial products (SMP) in the reactors. Interestingly, impact of acidogens on short term critical flux tests was not significant, but this may be a consequence of the experimental set-up.

  • implications of changes in solids retention time on long term evolution of sludge Filterability in anaerobic membrane bioreactors treating high strength industrial wastewater
    Water Research, 2014
    Co-Authors: Recep Kaan Dereli, Frank P Van Der Zee, Aurelie Grelot, Barry Heffernan, Jules B Van Lier
    Abstract:

    Abstract Long-term experiments were conducted to assess the impact of changing the solids retention time (SRT) on sludge Filterability in anaerobic membrane bioreactors (AnMBRs), treating corn-based bioethanol thin stillage. Well established parameters, such as capillary suction time (CST) and specific resistance to filtration (SRF), developed for sludge dewatering, were used to evaluate the SRT effect on sludge Filterability. Our results clearly demonstrated that SRT is one of the most important factors influencing sludge Filterability in AnMBRs. SRT effects the accumulation of fine particles and solutes, which were found to affect attainable flux and fouling, in reactor broth. A better Filterability was observed at a SRT of 20 days compared to elevated SRTs, i.e. 50 days. A clear correlation between sludge filtration characteristics and membrane filtration resistance could not be established especially at short SRTs, whereas many parameters such as total suspended solids (TSS), CST, soluble microbial products (SMP) and supernatant Filterability were found to be mutually correlated. Net membrane fluxes between 9 and 13 L m −2  h −1 were obtained at 0.5 m s −1 cross-flow velocity and the long term fouling was controlled by using frequent filtration and backwash cycles.

  • potentials of anaerobic membrane bioreactors to overcome treatment limitations induced by industrial wastewaters
    Bioresource Technology, 2012
    Co-Authors: Recep Kaan Dereli, Mustafa Evren Ersahin, Hale Ozgun, Izzet Ozturk, David Jeison, Jules B Van Lier
    Abstract:

    This review presents a comprehensive summary on applications of anaerobic membrane bioreactor (AnMBR) technology for industrial wastewaters in view of different aspects including treatability and Filterability. AnMBRs present an attractive option for the treatment of industrial wastewaters at extreme conditions, such as high salinity, high temperature, high suspended solids concentrations, and toxicity that hamper granulation and retention of biomass or reduce the biological activity. So far, most of the research has been conducted at laboratory scale; however, also a number of full-scale AnMBR systems is currently being operated worldwide. Membrane fouling, a multivariable process, is still a research quest that requires further investigation. In fact, membrane fouling and flux decline present the most important reasons that hamper the wide-spread application of full-scale reactors. This paper addresses a detailed assessment and discussion on treatability and Filterability of industrial wastewaters in both lab- and full-scale AnMBR applications, the encountered problems and future opportunities.

Jules B Van Lier - One of the best experts on this subject based on the ideXlab platform.

  • biological performance and sludge Filterability of anaerobic membrane bioreactors under nitrogen limited and supplied conditions
    Water Research, 2018
    Co-Authors: Recep Kaan Dereli, Xiaofei Wang, Frank P Van Der Zee, Jules B Van Lier
    Abstract:

    Abstract The impact of nitrogen on biological performance and sludge Filterability of anaerobic membrane bioreactors was investigated in two lab-scale cross-flow anaerobic membrane bioreactors that were fed with cheese whey at two different COD:TKN ratios (50 and 190). Nitrogen deprivation adversely affected the biological treatment performance and reactor stability, as indicated by volatile fatty acids accumulation. On the other hand, nitrogen (urea) supplementation resulted in a reduced sludge median particle size and decreased sludge Filterability. Standard Filterability parameters such as capillary suction time and specific resistance to filtration tended to rapidly increase in the nitrogen supplemented reactor. The critical fluxes in the nitrogen limited and supplemented reactors were 20 and 9 L m−2 h−1, respectively. The rapid deterioration of sludge Filterability under nitrogen supplemented conditions was attributed to abundant growth of dispersed biomass. Thus, the COD:TKN ratio of wastewater affected both bioconversion and Filterability performance in the anaerobic membrane bioreactors.

  • a systematic study on the effect of substrate acidification degree and acidogenic biomass on sludge Filterability
    Water Research, 2015
    Co-Authors: Recep Kaan Dereli, Frank P Van Der Zee, Lefki Loverdou, Jules B Van Lier
    Abstract:

    The influence of substrate acidification on sludge filtration characteristics was systematically investigated by using short term filtration tests. Four reactors were operated with raw and acidified whey permeate in order to evaluate the effect of acidogens on sludge Filterability. The results showed that feeding non-acidified substrate promoted the growth of acidogens which in return decreased the median particle size of the sludge and adversely influenced specific resistance to filtration (SRF). In addition to the presence of acidogens, the food to mass (F:M) ratio was found as an important operation parameter on sludge Filterability. Various Filterability indicators, such as capillary suction time (CST), SRF and supernatant Filterability, tended to became worse at increased F:M ratios. The decreased Filterability at high F:M ratio was attributed to the accumulation of soluble microbial products (SMP) in the reactors. Interestingly, impact of acidogens on short term critical flux tests was not significant, but this may be a consequence of the experimental set-up.

  • implications of changes in solids retention time on long term evolution of sludge Filterability in anaerobic membrane bioreactors treating high strength industrial wastewater
    Water Research, 2014
    Co-Authors: Recep Kaan Dereli, Frank P Van Der Zee, Aurelie Grelot, Barry Heffernan, Jules B Van Lier
    Abstract:

    Abstract Long-term experiments were conducted to assess the impact of changing the solids retention time (SRT) on sludge Filterability in anaerobic membrane bioreactors (AnMBRs), treating corn-based bioethanol thin stillage. Well established parameters, such as capillary suction time (CST) and specific resistance to filtration (SRF), developed for sludge dewatering, were used to evaluate the SRT effect on sludge Filterability. Our results clearly demonstrated that SRT is one of the most important factors influencing sludge Filterability in AnMBRs. SRT effects the accumulation of fine particles and solutes, which were found to affect attainable flux and fouling, in reactor broth. A better Filterability was observed at a SRT of 20 days compared to elevated SRTs, i.e. 50 days. A clear correlation between sludge filtration characteristics and membrane filtration resistance could not be established especially at short SRTs, whereas many parameters such as total suspended solids (TSS), CST, soluble microbial products (SMP) and supernatant Filterability were found to be mutually correlated. Net membrane fluxes between 9 and 13 L m −2  h −1 were obtained at 0.5 m s −1 cross-flow velocity and the long term fouling was controlled by using frequent filtration and backwash cycles.

J.h.j.m. Van Der Graaf - One of the best experts on this subject based on the ideXlab platform.

  • impact of suspended solids concentration on sludge Filterability in full scale membrane bioreactors
    Journal of Membrane Science, 2015
    Co-Authors: M Lousada D C Ferreira, J.b. Van Lier, J.h.j.m. Van Der Graaf
    Abstract:

    The relation between activated sludge Filterability and mixed liquor suspended solids (MLSS) concentration in membrane bioreactors (MBRs) is framed in a single hypothesis, explaining results seemingly contradictory. A total of 44 activated sludge samples were collected and analyzed on a variety of parameters, i.e. Filterability, MLSS concentration, soluble microbial products (SMP) concentrations and particle size distribution in the range of 2-100 ?m and of 0.4-5.0 ?m. The sludge Filterability was assessed by using the Delft Filtration Characterization method (DFCm). In order to investigate the impact of MLSS concentration, identical samples were diluted with permeate. Results showed that dilution of the samples led to an increased activated sludge Filterability, but only when the starting MLSS concentration was below the apparent critical value of 10.5 g/L. As opposed, the Filterability of sludge with MLSS concentrations above 10.5 g/L, and which was characterized by a moderate to good filtration quality, i.e. ?R20<1 [x1012m-1], worsened when diluted. The specific resistance times the particle concentration of a cake layer obtained when filtrating sludge of moderate to good Filterability and MLSS concentration above the apparent critical value, was 5.5 times smaller compared to the cake layer of sludge with MLSS concentration below the critical value. Results from SMP assessment and particle counting in the range 2-100 ?m showed that reduction in sludge mass and de-flocculation occurred, upon dilution of all samples. However, when diluting sludge samples with MLSS concentrations exceeding 10.5 g/L and which were characterized by a moderate to good filtration characteristics, there was also release of particles below 0.4 ?m, opposite to dilutions of samples with MLSS concentrations below 10.5 g/L. We postulate that sludge, which is characterized by a moderate to good Filterability, having an MLSS concentration above the apparent critical value of 10.5 g/L, is likely to retain particles smaller than 0.4 ?m in its mass, as opposed to sludge with MLSS concentration below the apparent critical value. Our work indicates that there are optimal MLSS concentration ranges in MBR technology, to promote good filterable sludge quality in order to avoid fouling.

  • analysis of the Filterability in industrial mbrs influence of activated sludge parameters and constituents on Filterability
    Journal of Membrane Science, 2011
    Co-Authors: J A Gil, J.h.j.m. Van Der Graaf, J.b. Van Lier, Pawel Krzeminski, T Wijffels, Daniel Prats
    Abstract:

    Abstract The Filterability of the activated sludge is an important characteristic that offers valuable information about the filtration process in membrane bioreactors (MBR). MBR operators rely on permeability values to monitor the process. However, results obtained in this and other studies have demonstrated that permeability alone is a weak parameter, as it provides no specific information about which factors are determining it. Aiming to elucidate the causes affecting the Filterability of the activated sludge, some research groups have quantified and correlated the Filterability with different activated sludge parameters, mostly for municipal MBRs. This paper however, offers a different approach focusing on an industrial scenario. A representative sample of eleven full-scale industrial MBRs has been selected in centre-Europe to conduct a study, in order to quantify both, the impact of parameters and constituents of industrial activated sludge on Filterability. Temperature, membrane configuration, hydraulic retention time, solids retention time, and the soluble organic fraction did not show any impact on Filterability whereas the mixed liquor suspended solids and the food to microorganism ratio demonstrated a slight influence. Among all parameters analyzed, the colloidal fraction played the most important role in the fouling process indicating that for industrial activated sludge, the membrane acts as a biomass barrier merely, since a high percentage (>75%) of the soluble organic fraction is small enough to pass the membrane (0.03 μm). Finally, Filterability measurements suggest that on the whole, an optimization in the operation of industrial MBRs is plausible.

  • activated sludge characteristics affecting sludge Filterability in municipal and industrial mbrs unraveling correlations using multi component regression analysis
    Journal of Membrane Science, 2011
    Co-Authors: R Van Den Broeck, J.h.j.m. Van Der Graaf, Pawel Krzeminski, J Van Dierdonck, Geert Gins, M Lousadaferreira, J F Van Impe, Ilse Smets, J.b. Van Lier
    Abstract:

    In the field of membrane bioreactors (MBRs) many membrane fouling related questions still remain unanswered. The goal of this research is to unveil some of the black-box features of activated sludge Filterability by correlating the results from activated sludge Filterability measurements following the Delft Filtration Characterization method (DFCm) with a large set of activated sludge characteristics. Ten different MBRs in Belgium and the Netherlands were sampled in both winter and summer. All samples were subjected to the DFCm, automated image analysis and an extensive set of standardized measurements. No clear correlation could be found between a single sludge parameter and activated sludge Filterability. However, a combination of sludge morphology and relative hydrophobicity (RH) allows for a clear classification of activated sludge into two classes, i.e., bad and poor to good, implying that deflocculation and a low RH have a negative impact on activated sludge Filterability. Furthermore, for sludge samples having poor to good Filterability, accurate estimations of sludge Filterability can be made when including more parameters. The main conclusion is that Filterability can be predicted by analyzing the bioflocculation state of the activated sludge.

  • Particle counting as a tool to predict Filterability in membrane bioreactors activated sludge
    Water Science and Technology, 2011
    Co-Authors: M. Lousada-ferreira, A. Moreau, J.b. Van Lier, J.h.j.m. Van Der Graaf
    Abstract:

    Activated sludge quality is one of the major factors influencing flux decline in membrane bioreactors (MBRS). Sludge Filterability is a recognized parameter to characterize the physical properties of activated sludge. Decrease in Filterability is linked to a higher number of submicron particles. In our present research we studied whether particle counting techniques can be used to indicate deflocculation of the sludge suspended fraction to submicron particles, causing the aforementioned Filterability decrease. A total number of 105 activated sludge samples were collected in four full scale municipal MBRS. Samples were tested for Filterability and particle counting in the range 2-100 microm. In 88% of the membrane tank samples the Filterability varied between good and poor, characterized by the deltaR20, being 0 < deltaR20 < 1. Filterability varied following the season of the year, stability of the MBR operation and recirculation ratio. The membrane tank Filterability can be improved by applying low recirculation ratio between MBR tanks. The applied particle counting methodology generated reproducible and reliable results in the range 10-100 microm. Results show that differences in Filterability cannot be explained by variations in particle size distribution in the range 10-100 microm. However, measurable deflocculation might be masked by the large numbers of particles present. Therefore, we cannot exclude the suspended particles as a possible source of submicron particles that are subsequently responsible for MBR sludge Filterability deterioration.

  • Tracing membrane foulants in membrane bioreactors by filtration characterisation and fractionation
    Water Science & Technology: Water Supply, 2006
    Co-Authors: S.p. Geilvoet, H. Evenblij, M.j.j. Remy, H. Temmink, J.h.j.m. Van Der Graaf
    Abstract:

    A pilot MBR was fed with two different influent loading conditions, namely dry weather flow (DWF) and DWF with an additional discharge of wastewater from a local cheese factory. For both situations sludge was sampled from different tanks of the pilot (predenitrification, denitrification, nitrification and membrane tank). All sludge samples and the supernatant of sludge from the membrane tank were filtered under exactly the same conditions with a filtration characterisation unit. Besides this all samples were subdivided in different fractions (supernatant, 0.45 and 0.03 μm, 500, 100, 10 and 1 kDa) and analysed for their EPS concentrations (proteins and polysaccharides). The results show that the Filterability of the sludge changes with the sampling point and differs between the two influent loading conditions. Contrary to DWF conditions, for cheesy influent conditions sludge from the membrane tank has better Filterability than its supernatant. This suggests that the sludge forms a cake layer that protects the membrane against fouling by particles in the free water. No clear relation between Filterability and EPS concentrations of the different fractions was found.

J.b. Van Lier - One of the best experts on this subject based on the ideXlab platform.

  • impact of suspended solids concentration on sludge Filterability in full scale membrane bioreactors
    Journal of Membrane Science, 2015
    Co-Authors: M Lousada D C Ferreira, J.b. Van Lier, J.h.j.m. Van Der Graaf
    Abstract:

    The relation between activated sludge Filterability and mixed liquor suspended solids (MLSS) concentration in membrane bioreactors (MBRs) is framed in a single hypothesis, explaining results seemingly contradictory. A total of 44 activated sludge samples were collected and analyzed on a variety of parameters, i.e. Filterability, MLSS concentration, soluble microbial products (SMP) concentrations and particle size distribution in the range of 2-100 ?m and of 0.4-5.0 ?m. The sludge Filterability was assessed by using the Delft Filtration Characterization method (DFCm). In order to investigate the impact of MLSS concentration, identical samples were diluted with permeate. Results showed that dilution of the samples led to an increased activated sludge Filterability, but only when the starting MLSS concentration was below the apparent critical value of 10.5 g/L. As opposed, the Filterability of sludge with MLSS concentrations above 10.5 g/L, and which was characterized by a moderate to good filtration quality, i.e. ?R20<1 [x1012m-1], worsened when diluted. The specific resistance times the particle concentration of a cake layer obtained when filtrating sludge of moderate to good Filterability and MLSS concentration above the apparent critical value, was 5.5 times smaller compared to the cake layer of sludge with MLSS concentration below the critical value. Results from SMP assessment and particle counting in the range 2-100 ?m showed that reduction in sludge mass and de-flocculation occurred, upon dilution of all samples. However, when diluting sludge samples with MLSS concentrations exceeding 10.5 g/L and which were characterized by a moderate to good filtration characteristics, there was also release of particles below 0.4 ?m, opposite to dilutions of samples with MLSS concentrations below 10.5 g/L. We postulate that sludge, which is characterized by a moderate to good Filterability, having an MLSS concentration above the apparent critical value of 10.5 g/L, is likely to retain particles smaller than 0.4 ?m in its mass, as opposed to sludge with MLSS concentration below the apparent critical value. Our work indicates that there are optimal MLSS concentration ranges in MBR technology, to promote good filterable sludge quality in order to avoid fouling.

  • the influence of hydrolysis induced biopolymers from recycled aerobic sludge on specific methanogenic activity and sludge Filterability in an anaerobic membrane bioreactor
    Water Research, 2014
    Co-Authors: Dagmara Buntner, Henri Spanjers, J.b. Van Lier
    Abstract:

    The objective of the present study was to evaluate the impact of excess aerobic sludge on the specific methanogenic activity (SMA), in order to establish the maximum allowable aerobic sludge loading. In batch tests, different ratios of aerobic sludge to anaerobic inoculum were used, i.e. 0.03, 0.05, 0.10 and 0.15, showing that low ratios led to an increased SMA. However, the ratio 0.15 caused more than 20% SMA decrease. In addition to the SMA tests, the potential influence of biopolymers and extracellular substances, that are generated as a result of excess aerobic sludge hydrolysis, on membrane performance was determined by assessing the fouling potential of the liquid broth, taking into account parameters such as specific resistance to filtration (SRF) and supernatant Filterability (SF). Addition of aerobic sludge to the anaerobic biomass resulted in a high membrane fouling potential. The increase in biopolymers could be ascribed to aerobic sludge hydrolysis. A clear positive correlation between the concentration of the colloidal fraction of biopolymer clusters (cBPC) and the SRF was observed and a negative correlation between the cBPC and the SF measured at the end of the above described SMA tests. The latter implies that sludge filtration resistance increases when more aerobic sludge is hydrolyzed, and thus more cBPC is released. During AnMBR operation, proteins significantly contributed to sludge Filterability decrease expressed as SRF and SF, whereas the carbohydrate fraction of SMP was of less importance due to low concentrations. On the contrary, carbohydrates seemed to improve Filterability and diminish SRF of the sludge. Albeit, cBPC increase caused an increase in mean TMP during the AnMBR operation, confirming that cBPC is positively correlated to membrane fouling.

  • analysis of the Filterability in industrial mbrs influence of activated sludge parameters and constituents on Filterability
    Journal of Membrane Science, 2011
    Co-Authors: J A Gil, J.h.j.m. Van Der Graaf, J.b. Van Lier, Pawel Krzeminski, T Wijffels, Daniel Prats
    Abstract:

    Abstract The Filterability of the activated sludge is an important characteristic that offers valuable information about the filtration process in membrane bioreactors (MBR). MBR operators rely on permeability values to monitor the process. However, results obtained in this and other studies have demonstrated that permeability alone is a weak parameter, as it provides no specific information about which factors are determining it. Aiming to elucidate the causes affecting the Filterability of the activated sludge, some research groups have quantified and correlated the Filterability with different activated sludge parameters, mostly for municipal MBRs. This paper however, offers a different approach focusing on an industrial scenario. A representative sample of eleven full-scale industrial MBRs has been selected in centre-Europe to conduct a study, in order to quantify both, the impact of parameters and constituents of industrial activated sludge on Filterability. Temperature, membrane configuration, hydraulic retention time, solids retention time, and the soluble organic fraction did not show any impact on Filterability whereas the mixed liquor suspended solids and the food to microorganism ratio demonstrated a slight influence. Among all parameters analyzed, the colloidal fraction played the most important role in the fouling process indicating that for industrial activated sludge, the membrane acts as a biomass barrier merely, since a high percentage (>75%) of the soluble organic fraction is small enough to pass the membrane (0.03 μm). Finally, Filterability measurements suggest that on the whole, an optimization in the operation of industrial MBRs is plausible.

  • activated sludge characteristics affecting sludge Filterability in municipal and industrial mbrs unraveling correlations using multi component regression analysis
    Journal of Membrane Science, 2011
    Co-Authors: R Van Den Broeck, J.h.j.m. Van Der Graaf, Pawel Krzeminski, J Van Dierdonck, Geert Gins, M Lousadaferreira, J F Van Impe, Ilse Smets, J.b. Van Lier
    Abstract:

    In the field of membrane bioreactors (MBRs) many membrane fouling related questions still remain unanswered. The goal of this research is to unveil some of the black-box features of activated sludge Filterability by correlating the results from activated sludge Filterability measurements following the Delft Filtration Characterization method (DFCm) with a large set of activated sludge characteristics. Ten different MBRs in Belgium and the Netherlands were sampled in both winter and summer. All samples were subjected to the DFCm, automated image analysis and an extensive set of standardized measurements. No clear correlation could be found between a single sludge parameter and activated sludge Filterability. However, a combination of sludge morphology and relative hydrophobicity (RH) allows for a clear classification of activated sludge into two classes, i.e., bad and poor to good, implying that deflocculation and a low RH have a negative impact on activated sludge Filterability. Furthermore, for sludge samples having poor to good Filterability, accurate estimations of sludge Filterability can be made when including more parameters. The main conclusion is that Filterability can be predicted by analyzing the bioflocculation state of the activated sludge.

  • Particle counting as a tool to predict Filterability in membrane bioreactors activated sludge
    Water Science and Technology, 2011
    Co-Authors: M. Lousada-ferreira, A. Moreau, J.b. Van Lier, J.h.j.m. Van Der Graaf
    Abstract:

    Activated sludge quality is one of the major factors influencing flux decline in membrane bioreactors (MBRS). Sludge Filterability is a recognized parameter to characterize the physical properties of activated sludge. Decrease in Filterability is linked to a higher number of submicron particles. In our present research we studied whether particle counting techniques can be used to indicate deflocculation of the sludge suspended fraction to submicron particles, causing the aforementioned Filterability decrease. A total number of 105 activated sludge samples were collected in four full scale municipal MBRS. Samples were tested for Filterability and particle counting in the range 2-100 microm. In 88% of the membrane tank samples the Filterability varied between good and poor, characterized by the deltaR20, being 0 < deltaR20 < 1. Filterability varied following the season of the year, stability of the MBR operation and recirculation ratio. The membrane tank Filterability can be improved by applying low recirculation ratio between MBR tanks. The applied particle counting methodology generated reproducible and reliable results in the range 10-100 microm. Results show that differences in Filterability cannot be explained by variations in particle size distribution in the range 10-100 microm. However, measurable deflocculation might be masked by the large numbers of particles present. Therefore, we cannot exclude the suspended particles as a possible source of submicron particles that are subsequently responsible for MBR sludge Filterability deterioration.

J B Van Lier - One of the best experts on this subject based on the ideXlab platform.

  • impact of inflow conditions on activated sludge Filterability and membrane bioreactor mbr operational performance
    Desalination and Water Treatment, 2015
    Co-Authors: Pawel Krzeminski, J H J M Van Der Graaf, J B Van Lier
    Abstract:

    Operation and performance of membrane bioreactors (MBRs) for wastewater treatment is influenced by changes in activated sludge properties. Therefore, understanding of the factors influencing sludge Filterability is of major importance for efficient operation of MBR installations. This paper assesses the impact of the influent characteristics on activated sludge Filterability and treatment performance of full-scale MBRs. The full-scale MBRs were closely monitored both in summer and winter. The measurement campaign, consisting of activated sludge Filterability tests and physicochemical analyses, is supplemented with operational performance data evaluation of the various full-scale plants. Based on these data, it is shown that an undesired and refractory composition of incoming wastewater, hydraulic and/or organic load shocks, as well as abrupt temperature changes of the influent, lead to operational problems and affect sludge Filterability.

  • impact of temperature on raw wastewater composition and activated sludge Filterability in full scale mbr systems for municipal sewage treatment
    Journal of Membrane Science, 2012
    Co-Authors: Pawel Krzeminski, J H J M Van Der Graaf, J B Van Lier, A Iglesiasobelleiro, G Madebo, J M Garrido
    Abstract:

    Abstract The main objective of this study was to investigate the influence of seasonal temperature fluctuations on raw domestic wastewater composition and MBR sludge Filterability. The influent and sludge samples were collected from a full-scale MBR in Heenvliet. All samples were analyzed in terms of Filterability, particle size distribution, respirometry, fractionation and were further characterized by an extensive set of physicochemical measurements. Typical seasonal fluctuations and deterioration of activated sludge Filterability during low temperature periods were observed. Filterability deterioration at low temperatures was linked to the incoming organic load, reduced MBR biomass concentrations, increased VSS/TSS ratio and reduced biodegradation of wastewater in the mixed liquor. Biological activity of the biomass was concomitantly decreased with temperature to reach a minimum during the winter period. Results show that the colloidal and soluble fraction (