Optimisation and performance of NaClO-assisted maintenance cleaning for fouling control in membrane bioreactors.
Based on conventional chemical cleaning and physical backflush methods, a novel in situ chemical backflush method, i.e., chemically assisted maintenance cleaning with NaClO as the principal reagent, was developed for membrane fouling control in membrane bioreactors (MBRs). The results demonstrated that, compared with a control MBR with water backflush, the use of low NaClO loads had few adverse effects on nutrient removal; on the contrary, the exposure to NaClO enhanced the denitrification performance of the MBR as a result of the formation of sludge granules. Measurements of transmembrane pressure (TMP) showed that an NaClO backflush at 0.2 ppm could achieve effective membrane fouling control in MBRs. Ex situ backflush tests showed that an NaClO backflush enhanced the detachment of biopolymers from the fouled membranes compared with a water backflush. Comparative 16S rRNA sequencing showed differing bacterial community composition in the fouling layers of the two MBRs. Specifically, the NaClO backflush could suppress filament-caused membrane fouling (i.e., lowered the abundance of Thiothrix eikelboomii in the fouling layers). Both the water and NaClO backflush resulted in significant increases in the pure water permeability of the membranes as a result of the enlargement of membrane pores. The results of Fourier transform infrared spectrometry indicated that the frequent NaClO backflush did not change the functional groups of the active layer of the membranes significantly. This study could provide an alternative for the implementation of membrane cleaning in MBR plants.
SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China.
Zhizhen
Z
Wang
SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China. Electronic address: mengfg@mail.sysu.edu.cn.
Fangang
F
Meng
SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China.
Xiang
X
He
SYSU-HKUST Research Center for Innovative Environmental Technology (SHRCIET), School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510275, China.
Zhongbo
Z
Zhou
School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
Li-Nan
LN
Huang
Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China.
Shuang
S
Liang
D001419:Bacteria / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D057219:Biofouling / Q000517:prevention & control*; D019149:Bioreactors; D005798:Genes, Bacterial / Q000235:genetics; D008855:Microscopy, Electron, Scanning; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012973:Sodium Hypochlorite / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014865:Waste Disposal, Fluid / Q000379:methods*
D012336:RNA, Ribosomal, 16S; D012973:Sodium Hypochlorite
Activated sludge; Chemical cleaning; Membrane bioreactor; Membrane fouling; Wastewater treatment