Biogas production from saline wastewater of the evisceration process of the fish processing industry

Since 1950, the fisheries industry has increased with the growth of human population. These industries produced highly loaded and brackish wastewaters. Without proper treatment, these wastewaters can severely affect water bodies. In this work, we have studied the viability of the treatment of wastewaters, generated during the evisceration process of the fish processing industry, by using synthetic wastewater made of fish viscera (Chemical Oxygen Demand, COD = 2954.17 ± 128.07 mg.L¹), treated under anaerobic sludge conditions in order to work at high saline conditions. Three feeds to microorganism ratio were tested (0.274 ± 0.012, 0.129 ± 0.0055 and 0.077 ± 0.0035 gCOD.gSSV^-1), in order to improve the anaerobic reactor performance. COD removal, the maximum accumulated biogas and biogas yield were measured for testing the efficacy of the anaerobic sludge. COD removal efficiencies were above 80% at the three salinities. While biogas yield was reduced, the salinity was increased from 0 to 20 g.L^-1, and a high feed to microorganism ratio (0.274 ± 0.012 gCOD.gSSV^-1) was used. The inhibitory effect also was observed at low F/M ratio (0.077 ± 0.0035 gCOD.gSSV^-1). Although biogas yield reached acceptable values, biogas yield was reduced to 64%, when salinity was increased from 0 to 20 g.L^-1. The research on the use of anaerobic sludge conditioned at high salinity shows a promising perspective for the treatment and exploitation of wastewater, generated in the evisceration of fish, revealing the need for corresponding optimization of the process, to increase the yield in the production of biogas. Research on the use of anaerobic sludge conditioned at high salinity shows a promising scenario for the treatment and exploitation of evisceration wastewater, with the corresponding optimization of the process to increase the production of biogas.