On-line cake-layer management by trans-membrane pressure steady state assessment in Anaerobic Membrane Bioreactors for wastewater treatment

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.

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Fouling cake layer in a submerged anaerobic membrane bioreactor treating saline wastewaters: curse or a blessing?

Water Science & Technology ◽

10.2166/wst.2011.461 ◽

2011 ◽

Vol 63 (12) ◽

pp. 2902-2908 ◽

Cited By ~ 27

Author(s):

I. Vyrides ◽

D. C. Stuckey

Keyword(s):

Membrane Fouling ◽

Membrane Bioreactor ◽

Large Fraction ◽

Membrane Bioreactors ◽

Extracellular Polysaccharides ◽

Cake Layer ◽

Anaerobic Membrane Bioreactors ◽

Suspended Biomass ◽

Microbial Products

The treatment of inhibitory (saline) wastewaters is known to produce considerable amounts of soluble microbial products (SMPs), and this has been implicated in membrane fouling; the fate of these SMPs was of considerable interest in this work. This study also investigated the contribution of SMPs to membrane fouling of the; (a) cake layer/biofilm layer, (b) the compounds below the biofilm/cake layer and strongly attached to the surface of the membrane, (c) the compounds in the inner pores of the membrane, and (d) the membrane. It was found that the cake/biofilm layer was the main reason for fouling of the membrane. Interestingly, the bacteria attached to the cake/biofilm layer showed higher biodegradation rates compared with the bacteria in suspension. Moreover, the bacteria attached to the cake layer showed higher amounts of attached extracellular polysaccharides (EPS) compared with the bacteria in suspension, possibly due to accumulation of the released EPS from suspended biomass in the cake/biofilm layer. Molecular weight (MW) analysis of the effluent and reactor bulk showed that the cake layer can retain a large fraction of the SMPs in the reactor and prevent them from being released into the effluent. Hence, while cake layers lead to lower fluxes in submerged anaerobic membrane bioreactors (SAMBRs), and hence higher costs, they can improve the quality of the reactor effluent.

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Application of anaerobic membrane bioreactors to municipal wastewater treatment at ambient temperature: A review of achievements, challenges, and perspectives

Bioresource Technology ◽

10.1016/j.biortech.2018.07.050 ◽

2018 ◽

Vol 267 ◽

pp. 756-768 ◽

Cited By ~ 55

Author(s):

Zhen Lei ◽

Shuming Yang ◽

Yu-you Li ◽

Wen Wen ◽

Xiaochang C. Wang ◽

...

Keyword(s):

Wastewater Treatment ◽

Ambient Temperature ◽

Municipal Wastewater ◽

Membrane Bioreactors ◽

Municipal Wastewater Treatment ◽

Anaerobic Membrane Bioreactors

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Submerged anaerobic membrane bioreactor for wastewater treatment and energy generation

Water Science & Technology ◽

10.2166/wst.2015.135 ◽

2015 ◽

Vol 71 (11) ◽

pp. 1654-1660 ◽

Cited By ~ 6

Author(s):

J. B. Bornare ◽

U. S. Adhyapak ◽

G. P. Minde ◽

V. Kalyan Raman ◽

V. S. Sapkal ◽

...

Keyword(s):

Wastewater Treatment ◽

Oxygen Demand ◽

Energy Generation ◽

Evaluation Study ◽

Membrane Bioreactors ◽

Synthetic Wastewater ◽

Chemical Cleaning ◽

Membrane Flux ◽

Treated Effluent ◽

Anaerobic Membrane Bioreactors

Compared with conventional wastewater treatment processes, membrane bioreactors (MBRs) offer several advantages including high biodegradation efficiency, excellent effluent quality and smaller footprint. However, it has some limitations on account of its energy intensive operation. In recent years, there has been growing interest in use of anaerobic membrane bioreactors (AnMBRs) due to their potential advantages over aerobic systems, which include low sludge production and energy generation in terms of biogas. The aim of this study was to evaluate the performance of a submerged AnMBR for the treatment of synthetic wastewater having 4,759 mg/l chemical oxygen demand (COD). The COD removal efficiency was over 95% during the performance evaluation study. Treated effluent with COD concentration of 231 mg/l was obtained for 25.5 hours hydraulic retention time. The obtained total organic carbon concentrations in feed and permeate were 1,812 mg/l and 89 mg/l, respectively. An average biogas generation and yield were 25.77 l/d and 0.36 m3/kg COD, respectively. Evolution of trans-membrane pressure (TMP) as a function of time was studied and an average TMP of 15 kPa was found suitable to achieve membrane flux of 12.17 l/(m2h). Almost weekly back-flow chemical cleaning of the membrane was found necessary to control TMP within the permissible limit of 20 kPa.

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