Organic and Nitrogenous Matter Effects on the Denitrification of Saline and Protein-Rich Effluents

摘要

The separate effect of protein concentration, nitrate concentration and carbonitrogen (C/N) ratio on the rate and efficiency of nitrate reduction was studied in batch reactors fed with a mixture of a synthetic substrate and a saline protein-rich salmon-plant effluent. At a constant nitrate concentration (40 mg L~(-1)), the specific rate of nitrate removal decreased by 60% with increasing initial protein concentration (392 to 1900 mg L~(-1)) and ammonification prevailed under these conditions; meanwhile at a constant protein concentration (1104 mg L~(-1)), the specific rate of nitrate removal increased 58 times with increasing nitrate concentrations (0.5 to 78 mg L~(-1)) and denitrification was the main route for nitrate reduction. The C/N ratio had an inverse effect on the specific rate of denitrification; the latter ranged from 227 to 563 [mg NO_3~--N (g VSS·d)~(-1)] for a C/N ratio of 163 to 16 [mg TOC (total organic carbon) (mg NO_3~--N)~(-1)], respectively. On the other hand, the ammonia production rate was proportional up to a C/N ratio of 150.