Optimization of the Simultaneous Removal of Nitrogen and Organic Matter from Fishery Wastewaters

摘要

Anaerobic treatment of saline and protein-rich effluents reduces the organic concentration but forms ammonium that hinders nitrogen removal in a later aerobic treatment. The goal of this work was to optimize the design of a denitrifying-nitrifying system for the simultaneous removal of organic matter and nitrogenous compounds from fishery effluents to meet the Chilean legal standards and to compare pre- and post-denitrification processes in the biological treatment of high-strength effluents to minimize the total volume of biological reactors required. A predenitrifying system, that included three reactors—acidifying anaerobic filter, denitrifying (anoxic) filter, and aerobic-active sludge (nitrifying reactor) with recycle to the denitrifying reactor—reduced nitrogen to 0.33 g of total ammonia nitrogen (TAN) L~(-1) well above the allowed 0.05 g total nitrogen L~(-1). The predenitrifying system with a second denitrifying reactor, to which organic matter was added, met the legal organic matter and nitrogen emission concentrations (0.042 g TAN L~(-1)). Conversions were 99.0, 92.5, 90.9, and 99.0% for the anaerobic digestion, first denitrification, nitrification, and second denitrification, respectively.