The impacts of effluent pre-acidification on membrane filtration were evaluated in two anaerobic membrane bioreactors, named 1-AnMBR and 2-AnMBR, fed with raw effluent and effluent from an acidogenic reactor (AR), respectively. Besides the superior biological performance, 2-AnMBR presented less membrane fouling, showing a lower transmembrane pressure (TMP), compared to 1-AnMBR. By the end of operation, total apparent membrane resistance was 4.5 × 1012 m-1 and 8.1 × 1012 m-1 in 2-AnMBR and 1-AnMBR, respectively. Regarding the reactors' supernatants, lower soluble microbial products (SMP) and solid concentrations were observed in 2-AnMBR. Median particle sizes were 4, 178 and 132 μm in the supernatants of AR, 2-AnMBR and 1-AnMBR, respectively. Specific cake resistance (in m.kg-1 TSS) indicated better filterability of the sludge from the AR (7.44 × 1011), followed by 2-AnMBR (1.03 × 1012) and 1-AnMBR (1.02 × 1013), suggesting that the association between acidogenic and methanogenic consortia decreased sludge filterability. Therefore, effluent pre-acidification can be a strategy to reduce membrane fouling.
- Anaerobic membrane bioreactor
- Soluble microbial products