Membrane Fouling and Cleaning of A Thermophilic Anaerobic Membrane Reactor Treating Coffee Grounds and Sewage Sludge in a Long Term Continuous Operation with High Solid

Wei Qiao, Qian Li, Kazuyuki Takayanagi, Shofie Mohammad, Yu You Li



Anaerobic membrane reactor (AnMBR) has many advantages over continuously stirred tank reactor. Nevertheless, the suitability of a membrane reactor with high solid is a problem considering the potential membrane fouling. In this research, a thermophilic AnMBR was continuously operated for 238 days to investigate the membrane performance and to optimize the cleaning procedure by accumulating the total solid up to 75 g/L in the digester. The results showed that the membrane can be used for at least 150 days without cleaning. Flux decreased when changing the feedstock from coffee grounds to a mixture of coffee grounds and sewage sludge. The fine particles and high viscosity of sludge worsen the membrane permeability. Membrane fouling mainly originating from organic pollutants was proved through series cleaning: psychical, oxidation and citric acid. The effectiveness and the optimization of oxidation cleaning (NaClO of 0.1%, for 5 hours) were obtained by dead-end filtration tests.