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

Yi Ding,Dashuai Mu,Chao Jin,Chunpeng Zhang,Zhansheng Guo,Xuguang Hou,Zhenlin Liang,Changzi Ge,Zhipeng Li

doi:10.3390/membranes10090231

Abstract

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.

Highlights

Membrane separation technology coupled with an anaerobic bioreactor can be used for municipal sewage treatment [1]
The transmembrane pressure (TMP) jumped to 19.4 kpa at 106 d in the anaerobic membrane bioreactors (AnMBR) at 25 ◦ C, while the TMP in the AnMBR at 35 ◦ C remained stable and never underwent transition during the 180-day operation
The temperature differences between the AnMBR at 25 °C might have contributed to the more severe membrane fouling compared to the the two AnMBRs resulted a numberfouling of different physical biochemical of mixed at 35 °C

Summary

Introduction

Membrane separation technology coupled with an anaerobic bioreactor can be used for municipal sewage treatment [1]. The anaerobic membrane bioreactor (AnMBR) has attracted a lot of attention due to the advantages of less sludge production, higher loading rate, better quality effluent, and lower energy consumption [2]. The anaerobic process can be operated under different temperature [3]. As a result of the slow anaerobic microorganism growth, a long sludge retention time (SRT) is needed to achieve better pollutant removal efficiency, especially for municipal wastewater treatment [4]. The SRT should be longer than that commonly used at mesophilic temperatures, AnMBR operation near room temperature is technically feasible for municipal wastewater treatment [5].

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Conclusion