Mesophilic methane fermentation performance and ammonia inhibition of fish processing wastewater treatment using a self-agitated anaerobic baffled reactor.

The performance of the self-agitated anaerobic baffled reactor (SA-ABR) was investigated by increasing the organic loading rates (OLRs) from 0.46 to 9.50 g-COD/L/d. A good performance was achieved by the SA-ABR for the treatment of fish processing wastewater (FPW). The maximum OLR was 6.77 g-COD/L/d and the biogas production rate reached 2.16 L/L-reactor/d with a methane content of 69% at this OLR. The COD, carbohydrate, protein, lipid and VS removal efficiencies were as high as 64, 65, 68, 78 and 79%, respectively. Ammonia inhibition was assumed with inhibition concentrations of 10% (IC) and 20% (IC) at 4140 and 5780 mg/L. However, it was found that the reactor could tolerate ammonia at a high concentration range of 4500-6373 mg/L after a long-term continuous experiment. Ammonia inhibition was addressed by diluting the substrate and the sludge in the reactor with tap water.