scholarly journals Effect of Operating Conditions on Membrane Fouling in Pilot-Scale MBRs; Filaments Growth, Diminishing Dissolved Oxygen and Recirculation Rate of the Activated Sludge

Membranes ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 490
Author(s):  
Petros Gkotsis ◽  
Dimitra Banti ◽  
Anastasia Pritsa ◽  
Manassis Mitrakas ◽  
Petros Samaras ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Membrane Fouling ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Mixed Liquor ◽  
Filamentous Microorganisms ◽  
Recirculation Rate ◽  
Improved Performance

This is the first study that examines the effect of operating conditions on fouling of Membrane Bio-Reactors (MBRs), which treat municipal wastewater in field conditions, with specific regard to the controlled development of filamentous microorganisms (or filaments). The novelty of the present work is extended to minimize the dissolved oxygen (DO) in recirculated activated sludge for improving the process of denitrification. For this purpose, two pilot-scale MBRs were constructed and operated in parallel: i) Filament-MBR, where an attempt was made to regulate the growth of filaments by adjustment of DO, the Food-to-Microorganisms (F/M) ratio and temperature, and ii) Control-MBR, where a gentle stirring tank was employed for the purpose of zeroing the DO in the recycled sludge. Results showed that low temperature (< 15 °C) slightly increased the number of filaments in the Filament-MBR which, in turn, decreased the Trans-Membrane Pressure (TMP). As the Soluble Microbial Products (SMP) and the colloids are considered to be the basic foulants of membranes in MBR systems, specific attention was directed to keep their concentration at low values in the mixed liquor. The low F/M ratio in the aeration tanks which preceded the membrane tank was achieved to keep the SMP proteins and carbohydrates at very low values in the mixed liquor, i.e., less than 6 mg/L. Moreover, as a result of the low recirculation rate (2.6∙Qin), good aggregation of the produced excess sludge was achieved, and low concentration of colloids with a size ≤50 nm (nearly the membranes’ pore size used for filtration/separation) was measured, accounted for maximum 15% of the total colloids. Additionally, the increase in filamentous population at the Filament-MBR contributed to the further reduction of colloids in the mixed liquor at 7.9%, contributing beneficially to the reduction of TMP and of membrane fouling. The diminishing of DO in the recirculated sludge improved denitrification, and resulted in lower concentrations of Ν-NO3− and TN in the effluent of the Control-MBR. Furthermore, the recirculation rate of Qr = 2.6∙Qin, in comparison with Qr = 4.3∙Qin, resulted in improved performance regarding the removal of N-NH4+. Finally, high organics removal and ammonium nitrification was observed in the effluent of both pilots, since COD and Ν-ΝΗ4+ concentrations were generally in the range of 10–25 mg/L and < 0.1 mg/L, respectively.

Membrane fouling caused by sub-micron particles in a mixed liquor suspension of an MBR

2013 ◽  
Vol 67 (11) ◽  
pp. 2602-2607 ◽  
Author(s):  
K. Kimura ◽  
R. Ogyu ◽  
T. Miyoshi ◽  
T. Naruse ◽  
T. Tsuyuhara ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Membrane Fouling ◽  
Municipal Wastewater ◽  
Size Fraction ◽  
Fourier Transform Infrared ◽  
Pilot Scale ◽  
Membrane Bioreactors ◽  
Ftir Analysis ◽  
Mixed Liquor ◽  
Pore Plugging

Membrane fouling needs to be mitigated for widespread use of membrane bioreactors (MBRs). It has been pointed out that particles with small sizes found in supernatants (sub-micron particles) of mixed liquor suspensions of MBRs are important in the evolution of membrane fouling of this technology. However, information on characteristics of sub-micron particles in MBRs is still insufficient. In this study, a pilot-scale MBR treating municipal wastewater was used to investigate and characterize sub-micron particles in an MBR and to identify the size fraction(s) responsible for irreversible fouling in an MBR. It was clearly shown that characteristics of sub-micron particles in the MBR varied considerably depending on their sizes. Results of Fourier transform infrared (FTIR) analysis and monosaccharide analysis suggested that irreversible fouling in this study was mainly caused by the specific size fraction of 0.1–0.45 μm, which was close to the size of micropores of the membrane used. Pore plugging might explain this to some extent.

scholarly journals The Use of Natural Minerals in a Pilot-Scale MBR for Membrane Fouling Mitigation

Separations ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 24 ◽  
Author(s):  
Petros Gkotsis ◽  
Efrosini Peleka ◽  
Anastasios Zouboulis
Keyword(s):  
Membrane Fouling ◽  
Municipal Wastewater ◽  
High Strength ◽  
Pilot Scale ◽  
Aeration Tank ◽  
Batch Mode ◽  
Natural Minerals ◽  
N Removal ◽  
Filamentous Microorganisms ◽  
High Concentrations

This study examines the effect of bentonite and zeolite concentration (0.25–5 g/L) on the membrane fouling of a fully automated, pilot-scale membrane bioreactor (MBR) treating high-strength synthetic municipal wastewater. Reversible fouling was estimated by sludge filterability measurements and irreversible fouling was estimated by the reduction of the carbohydrate fraction of soluble microbial products (SMPc), which are considered to be significant MBR foulants. Both minerals were added to biomass samples (during batch-mode experiments) which were obtained from the system’s aeration tank. Results showed that the optimal bentonite and zeolite concentrations were 3.5–4 g/L and 2.5–3.5 g/L, respectively. Interestingly, above these values, the addition of both minerals increased the examined fouling indices, i.e., the measured filterability times and the SMPc concentration, implying that they might act as foulants at high concentrations. Optical microscopy images of the biomass samples showed that the addition of minerals at the optimal concentrations did not affect significantly filamentous microorganisms, since filament index (FI) was practically unaffected (~2). Finally, regarding the system’s treating performance, it was found that the pilot-scale MBR can operate successfully with high-strength synthetic municipal wastewater, since remarkable behaviour was exhibited in terms of organics (BOD5, COD) and ammonium (NH4+-N) removal (>98%).

Proteins causing membrane fouling in membrane bioreactors

2015 ◽  
Vol 72 (6) ◽  
pp. 844-849 ◽  
Author(s):  
Taro Miyoshi ◽  
Yuhei Nagai ◽  
Tomoyasu Aizawa ◽  
Katsuki Kimura ◽  
Yoshimasa Watanabe
Keyword(s):  
Membrane Fouling ◽  
Municipal Wastewater ◽  
Polyacrylamide Gel Electrophoresis ◽  
Pilot Scale ◽  
Membrane Bioreactors ◽  
Operating Conditions ◽  
Sequencing Analysis ◽  
2D Page ◽  
Side Stream ◽  
Significant Difference

In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

Nanofiltration of colored surface water: Quebec's experience

2003 ◽  
Vol 3 (5-6) ◽  
pp. 15-22
Author(s):  
P. Kouadio ◽  
M. Tétrault
Keyword(s):  
Drinking Water ◽  
Surface Water ◽  
Membrane Fouling ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Quebec City ◽  
Water Regulation ◽  
Eastern Canada

Three colored surface water nanofiltration pilot-scale projects were conducted in the province of Quebec (eastern Canada), between November 2000 and March 2002, by the company H2O Innovation (2000) inc., for the municipalities of Lac Bouchette, Latulipe-et-Gaboury and Charlesbourg (now part of Quebec City). Results indicated that nanofiltration permeate quality has an advance on present drinking water regulation standard in Quebec, but important membrane fouling occurred. Fouling can be controlled by pretreatment and optimization of the operating conditions.

scholarly journals Membrane Fouling Controlled by Adjustment of Biological Treatment Parameters in Step-Aerating MBR

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 553
Author(s):  
Dimitra C. Banti ◽  
Manassis Mitrakas ◽  
Petros Samaras
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Municipal Wastewater ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Aeration Tank ◽  
Filamentous Bacteria ◽  
Membrane Performance ◽  
Low Concentrations ◽  
Fouling Reduction

A promising solution for membrane fouling reduction in membrane bioreactors (MBRs) could be the adjustment of operating parameters of the MBR, such as hydraulic retention time (HRT), food/microorganisms (F/M) loading and dissolved oxygen (DO) concentration, aiming to modify the sludge morphology to the direction of improvement of the membrane filtration. In this work, these parameters were investigated in a step-aerating pilot MBR that treated municipal wastewater, in order to control the filamentous population. When F/M loading in the first aeration tank (AT1) was ≤0.65 ± 0.2 g COD/g MLSS/d at 20 ± 3 °C, DO = 2.5 ± 0.1 mg/L and HRT = 1.6 h, the filamentous bacteria were controlled effectively at a moderate filament index of 1.5–3. The moderate population of filamentous bacteria improved the membrane performance, leading to low transmembrane pressure (TMP) at values ≤2 kPa for a great period, while at the control MBR the TMP gradually increased reaching 14 kPa. Soluble microbial products (SMP), were also maintained at low concentrations, contributing additionally to the reduction of ΤΜP. Finally, the step-aerating MBR process and the selected imposed operating conditions of HRT, F/M and DO improved the MBR performance in terms of fouling control, facilitating its future wider application.

scholarly journals Long-Term Investigation into the Membrane Fouling Behavior in Anaerobic Membrane Bioreactors for Municipal Wastewater Treatment Operated at Two Different Temperatures

Membranes ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 231
Author(s):  
Yi Ding ◽  
Zhansheng Guo ◽  
Zhenlin Liang ◽  
Xuguang Hou ◽  
Zhipeng Li ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Membrane Fouling ◽  
Municipal Wastewater ◽  
Membrane Bioreactors ◽  
Municipal Wastewater Treatment ◽  
Sludge Flocs ◽  
Microbial Product ◽  
Anaerobic Membrane Bioreactors ◽  
Sludge Particle

In this study, the characteristics of activated sludge flocs were investigated and their effects on the evolution of membrane fouling were considered in the anaerobic membrane bioreactors (AnMBR), which were operated at 25 and 35 °C for municipal wastewater treatment. It was found that the membrane fouling rate of the AnMBR at 25 °C was more severe than that at 35 °C. The membrane fouling trends were not consistent with the change in the concentration of soluble microbial product (SMP). The larger amount of SMP in the AnMBR at 35 °C did not induce more severe membrane fouling than that in the AnMBR at 25 °C. However, the polysaccharide and protein concentration of extracellular polymeric substance (EPS) was higher in the AnMBR at 25 °C in comparison with that in the AnMBR at 35 °C, and the protein/polysaccharide ratio of the EPS in the AnMBR at 25 °C was higher in contrast to that in the AnMBR at 35 °C. Meanwhile, the fouling tendencies measured for the AnMBRs could be related to the characteristics of loosely bound EPS and tightly bound EPS. The analysis of the activated sludge flocs characteristics indicated that a smaller sludge particle size and more fine flocs were observed at the AnMBR with 25 °C. Therefore, the membrane fouling potential in the AnMBR could be explained by the characteristics of activated sludge flocs.

scholarly journals Influence of dissolved oxygen on nitrification kinetics in a circulating bed reactor

1998 ◽  
Vol 37 (4-5) ◽  
pp. 189-193 ◽  
Author(s):  
V. Lazarova ◽  
R. Nogueira ◽  
J. Manem ◽  
L. Melo
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Municipal Wastewater ◽  
Ammonia Concentration ◽  
Pilot Scale ◽  
Biofilm Reactor ◽  
Laboratory Scale ◽  
Nitrification Rate ◽  
Nitrification Kinetics ◽  
Laboratory Scale Reactor

The influence of dissolved oxygen concentration in nitrification kinetics was studied in a new biofilm reactor, the circulating bed reactor (CBR). The study was carried out partly at laboratory scale with synthetic water containing inorganic carbon and nitrogen compounds, and partly at pilot scale for secondary and tertiary nitrification of municipal wastewater. The experimental results showed that either the ammonia or the oxygen concentration could be limiting for the nitrification rate. The transition from ammonia to oxygen limiting conditions occurred for an oxygen to ammonia concentration ratio of about 1.5 - 2 gO2/gN-NH4+ for both laboratory- and pilot-scale reactors. The nitrification kinetics of the laboratory-scale reactor was close to a half order function of the oxygen concentration, when oxygen was the rate limiting substrate.

Research on Low Concentration Municipal Wastewater Removal Rate with Chemical-Biological Flocculation and Suspended Medium Process

2012 ◽  
Vol 599 ◽  
pp. 387-390
Author(s):  
Xing Yu Bian ◽  
Xing Sheng Kang ◽  
Yi Li ◽  
Yu Lin Sun ◽  
Min Kong ◽  
...  
Keyword(s):  
Municipal Wastewater ◽  
Removal Rate ◽  
Pilot Scale ◽  
Pollutant Removal ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Optimal Operating ◽  
Operational Parameter ◽  
Low Concentration ◽  
Scale Test

In this paper, chemical and biological flocculation and suspended medium process was applied to treat low concentration municipal wastewater in a pilot scale test in order to find the optimum operational parameter. The results showed that: system on pollutant removal mainly on chemical and biological flocculation reaction pool, Under the optimal operating condition, CODCr, TP and SS removal efficiencies reached 75.5％, 76％and 90.5％ respectively, and the CODCr, TP, SS concentrations of effluent meet the National Wastewater Integrated Discharge Standard. The optimum operating conditions according to the local actual situation, running for more than half a year, for the optimization of control parameters for the contrast obtained.

Environmental performance of an integrated fixed-film activated sludge (IFAS) reactor treating actual municipal wastewater during start-up phase

2015 ◽  
Vol 72 (10) ◽  
pp. 1840-1850 ◽  
Author(s):  
Nitin Kumar Singh ◽  
Absar Ahmad Kazmi ◽  
Markus Starkl
Keyword(s):  
Activated Sludge ◽  
Pathogenic Bacteria ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Lessons Learned ◽  
Present System ◽  
Salmonella Spp ◽  
Start Up ◽  
Fixed Film

The present study summarizes the start-up performance and lessons learned during the start-up and optimization of a pilot-scale plant employing integrated fixed film activated sludge (IFAS) process treating actual municipal wastewater. A comprehensive start-up was tailored and implemented to cater for all the challenges and problems associated with start-up. After attaining desired suspended biomass (2,000–3,000 mg/L) and sludge age (∼7 days), the average biological oxygen demand (BOD) and chemical oxygen demand (COD) removals were observed as 77.3 and 70.9%, respectively, at optimized conditions, i.e. hydraulic retention time (HRT), 6.9 h; return sludge rate, 160%. The influent concentrations of COD, BOD, total suspended solids, NH3-N, total nitrogen and total phosphorus were found to be in the range of 157–476 mg/L, 115–283 mg/L, 152–428 mg/L, 23.2–49.3 mg/L, 30.1–52 mg/L and 3.6–7.8 mg/L, respectively, and the minimum effluent concentrations were achieved as ∼49 mg/L, 23 mg/L, 35 mg/L, 2.2 mg/L, 3.4 mg/L and 2.8 mg/L, respectively, at optimum state. The present system was found effective in the removal of pathogenic bacteria (Escherichia coli, 79%; Salmonella spp., 97.5%; Shigella spp., 92.9%) as well as coliforms (total coliforms, 97.65%; faecal coliforms, 80.35%) without any disinfection unit. Moreover it was observed that the time required for the stabilization of the plant was approximately 3 weeks if other parameters (sludge age, HRT and dissolved oxygen) are set to optimized values.

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