Advanced methanogenic performance and fouling mechanism investigation of a high-solid anaerobic membrane bioreactor (AnMBR) for the co-digestion of food waste and sewage sludge. (15th December 2020)

• Record Type: Journal Article
• Authors: Cheng, Hui; Li, Yemei; Guo, Guangze; Zhang, Tao; Qin, Yu; Hao, Tianwei; Li, Yu-You
• Is Part Of: Water research. Volume 187(2020)
• Publication Date: 2020-12-15
• Subjects: Sewage sludge -- Food waste -- Anaerobic co-digestion -- High-solid AnMBR -- Fouling mechanism; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2020.116436
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Advanced co-digestion of food waste and sewage sludge was performed by an AnMBR. The optimal FW/SeS ratio for co-digestion performance was75%:25% among other ratios. The synergistic effect of sewage sludge and food waste co-digestion was revealed. Membrane rejected 90.2%, 82.2% and 72.3% of S-COD, S-carbohydrate and S-protein. To explain the fouling mechanism, external forces on sludge flocs were firstly analyzed. Abstract: Disposal of the increasingly huge amounts of sewage sludge (SeS) has become an impending problem worldwide. To solve this problem, a high-solid anaerobic membrane bioreactor (AnMBR) was used for the anaerobic co-digestion (AcoD) of SeS and food waste (FW). This study investigated the effects of SeS ratio on the methanogenic performance of the AcoD with a gradual increase value from 0 to 25%, 50%, 75% and 100% (total solids based). The results showed that the highest methanogenic performance was achieved at mono FW digestion. As for the co-digestion, the optimal FW/SeS ratio for methanogenic performance was 75%:25% among all the mixing ratios. The COD based biogas yield and methane yield were 0.498 L-biogas/g-CODfed and 0.295 L-CH4 /g-CODfed at this optimal mixing ratio, which were 67.7% and 67.6% higher than those of the mono SeS digestion, respectively. The upgraded values were attributed to the improved hydrolysis ratio (by 8.14%) and the balanced carbon-to-nitrogen (C/N) ratio by co-digestion with FW, which synergistically stimulated methanogenesis ratio by 81.0%. The continuous membrane filtration property was investigated and four typical trans-membrane pressure (TMP) variation curves at different fouling degrees were determined. The membrane could sustainably operate at a flux of 6 L/m 2 /h (LMH) at the mixed liquor total solids (MLTS) concentration of 25 - 30 g/L. The combination of continuous membrane filtration property, particle size distribution of the mixed liquor and the external forces analysis was firstly applied to unravel the membrane fouling mechanism of a high-solid AnMBR. The result of this study will contribute to the establishment of an efficient FW and SeS treatment strategy. Graphical abstract: Image, graphical abstract