Nitrogen Removal from Dye-Industry Wastewater Using a Novel Nonwoven Support-Surrounded Cell Reactor

Abstract

Dye-industry wastewaters contain high levels of organic nitrogen derived from urea. Thus, effective nitrogen removal methods are needed to meet regulatory standards prior to discharging effluent to receiving water bodies. A novel nonwoven support-surrounded cell (SSC) process was developed and continuous treatment experiments were conducted using a bench-scale SSC reactor. Nitrification efficiencies of the SSC treatment process using activated-sludge seeds from domestic and dye-industry wastewater treatment plants were about 22% and 55%, respectively. These efficiencies, though, could not be maintained more than 20 days. By adding NaHCO₃ as an inorganic carbon source, nitrification efficiency could be improved to about 62%, but this could not be maintained more than 25days. In additions, dye chemicals and dye-reduction inhibitors added to the influent wastewater had no effect on nitrification and denitrification reactions. High nitrification efficiencies, however, could be maintained for more than 100 days by supplementing phosphorus to the influent wastewater. Using a synthetic dye wastewater supplemented with inorganic carbon, phosphoric acid, and organic carbon at 1.5 times of total-nitrogen, a total-nitrogen removal efficiency of about 56% was obtained.