Methane production in an anaerobic osmotic membrane bioreactor using forward osmosis: Effect of reverse salt flux.

This study investigated the impact of reverse salt flux (RSF) on microbe community and bio-methane production in a simulated fertilizer driven FO-AnMBR system using KCl, KNO and KHPO as draw solutes. Results showed that KHPO exhibited the lowest RSF in terms of molar concentration 19.1mM/(m.h), while for KCl and KNO it was 32.2 and 120.8mM/(m.h), respectively. Interestingly, bio-methane production displayed an opposite order with KHPO, followed by KCl and KNO. Pyrosequencing results revealed the presence of different bacterial communities among the tested fertilizers. Bacterial community of sludge exposed to KHPO was very similar to that of DI-water and KCl. However, results with KNO were different since the denitrifying bacteria were found to have a higher percentage than the sludge with other fertilizers. This study demonstrated that RSF has a negative effect on bio-methane production, probably by influencing the sludge bacterial community via environment modification.