Volatile fatty acids production from fish wastewater

Abstract

In this work, two experiments were performed to investigate the production of volatile fatty acids (VFAs) through the anaerobic degradation of an effluent formed by cleaning, cooking and brine wastewaters collected from a fish processing industry. The first experiment was carried out in an anaerobic continuous reactor at pH 8. Several strategies were tested to improve the VFAs production such as different HRT (18 h, 14 h, 8 h and 6 h), different feed´s dilution (50 x, 10 x, 2 x and 1 x) and different feed´s salinity (2.8 g/L and 20 g/L). For several HRT and dilutions, the concentration of VFAs was very low and methane (CH4) was detected in the reactor. The increase of feed´s salinity appear to be a good strategy, since the concentration of VFAs increased (401 mg COD/L with 2.8 g/L of salt to 900 mg COD/L with 20 g/L of salt) and the percentage of CH4 in the reactor decreased. The second experiment was carried out in batches at different initial pH values (5, 6, 7, 8 and 9). Acetate and propionate were the main products obtained at the end of the experiment. The highest production of VFAs (1583 mg COD/L) was obtained at pH 6.