A gravity-driven membrane bioreactor in treating the real decentralized domestic wastewater: Flux stability and membrane fouling

Weijia Gong; Xianwu Liu; Jiashuo Wang; Yuzhou Zhao; Xiaobin Tang

doi:10.1016/j.chemosphere.2023.138948

A gravity-driven membrane bioreactor in treating the real decentralized domestic wastewater: Flux stability and membrane fouling

Chemosphere. 2023 Sep:334:138948. doi: 10.1016/j.chemosphere.2023.138948. Epub 2023 May 15.

Authors

Weijia Gong¹, Xianwu Liu², Jiashuo Wang², Yuzhou Zhao², Xiaobin Tang³

Affiliations

¹ School of Engineering, Northeast Agricultural University, 600 Changjiang Street, Xiangfang District, Harbin, 150030, PR China. Electronic address: gongweijia@126.com.
² School of Engineering, Northeast Agricultural University, 600 Changjiang Street, Xiangfang District, Harbin, 150030, PR China.
³ State Key Laboratory of Urban Water Resource and Environment (SKLUWRE), Harbin Institute of Technology, 73 Huanghe Road, Nangang District, Harbin, 150090, PR China. Electronic address: tang5462@163.com.

PMID: 37196796
DOI: 10.1016/j.chemosphere.2023.138948

Abstract

Domestic wastewater in decentralized sites is capturing increasing attention. However, conventional treatment technology is not sufficiently cost-effective. In this study, real domestic wastewater was treated directly using a gravity-driven membrane bioreactor (GDMBR) at 45 mbar without backwashing or chemical cleaning, and the effects of different membrane pore sizes (0.22 μm, 0.45 μm, and 150 kDa) on flux development and contaminants removal were examined. The results showed that the flux initially decreased and then stabilized throughout long-term filtration and that the stabilized flux level of the GDMBR equipped the membranes with the pore size of 150 kDa and 0.22 μm was higher than that of 0.45 μm membrane and was in the range of 3-4 L m^-2h^-1. The flux stability was related to spongelike and permeable biofilm generation on the membrane surface in the GDMBR system. The presence of aeration shear on the membrane surface would cause the slough off of biofilm from the membrane surface, especially in the scenarios of GDMBR with the membrane pore size of 150 kDa and 0.22 μm, contributing to lower accumulation of extracellular polymeric substance (EPS) and smaller biofilm thickness compared to that of 0.45 μm membrane. Furthermore, the GDMBR system achieved efficient removals of chemical oxygen demand (COD), and ammonia, with average removal efficiencies of 60-80% and 70%. The high biological activity and microbial community diversity within the biofilm would improve its biodegradation and should be responsible for the efficient removal performance of contaminants. Interestingly, the membrane effluent could effectively retain total nitrogen (TN) and total phosphorus (TP). Therefore, it's feasible to adopt the GDMBR process to treat the actual domestic wastewater in the decentralized locations, and these findings could be expected to develop some simple and environmentally friendly strategies for decentralized wastewater treatment with fewer inputs.

Keywords: Biofilm; Decentralized domestic wastewater treatment; Flux stabilization; Gravity-driven membrane bioreactor (GDMBR); Microbial community.

MeSH terms

Biofilms
Bioreactors
Extracellular Polymeric Substance Matrix
Membranes, Artificial
Waste Disposal, Fluid / methods
Wastewater*
Water Purification* / methods

Substances

Wastewater
Membranes, Artificial