Integrity Detection of Hollow Fiber Membrane Bioreactor Based on Fluorescence Spectrum Response
XIN Chang-chun1, 2, JIA Hui1, 2, 3*, LI Juan1, 2, WEN Hai-tao2, 3, LI Jing-yu2, WANG Jie1, 2, 3
1. State Key Laboratory of Separation Membranes and Membrane Processes, Tianjin Polytechnic University, Tianjin 300387, China
2. School of Environmental and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300387, China
3. Tianjin Engineering Center for Safety Evaluation of Water Quality & Safeguards Technology, Tianjin Polytechnic University, Tianjin 300387, China
Abstract：Membrane bioreactor (MBR) has the advantages of good effluent quality, small footprint and low sludge yield. However, once the membrane module is easy to be damaged during system operation, it will directly affect the effluent quality. In this study, the fluorescence emission spectral response was used as a technology to discuss the effects of hollow fiber membrane breakage rate, sludge concentration and breakage response time on membrane integrity monitoring in hollow fiber membrane bioreactor (MBR). The results showed that the MBR with hollow fiber membrane can retain the protein-like components (C1) in the sewage effectively, while the fulvic-like components (C2) and humic-like component (C3) have poor interception performance. Based on the experiment results, a fluorescent component of the ultraviolet region-like tryptophan component with peaks（Ex 230 nm/Em 335 nm）was used as the detection index, the fluorescence interception change index （fi） was used as the determination method, and the humic-like component with peaks（Ex 330 nm/Em 415 nm）was used as a reference index. Under the minimum detection accuracy θ, we found that the sludge concentration in the bioreactor had an important influence on the membrane breakage. The fi in different sludge concentrations from MBR-1 to MBR-5 were 12.4%, 3.7%, 13.9%, 15.9%, and 15.8%. The reference indicator factors (Ri) were 1.87, 1.92, 1.35, 2.19, and 2.69, which are all morethan the indication factor Rθ under the lowest detection accuracy. The fi can reflect the breakage of the membrane module effectively. As the number of broken fiber increases, the fi increases gradually. It is also found that the membrane modules have self-repairing ability due to the foulantblockage with system running. Thesludge would enter the membrane lumen through the damaged portion of the membrane module. Base on the valid detection of ultraviolet region-like tryptophan component, fluorescence will become stable after about 80 minutes of operation. The fi is satisfied tallies with the particle counter detection results. The system can identify the breakage information with very short response speed. The emission spectrum scanning based on the fluorescence spectral response can test the integrity of the membrane module, which is convenient, quick, and good practicability. Moreover, it can achieve the distributed detection in every membrane module.
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