Study of nitrogen removal efficiency of the filled bed reactors using alkali-treated corncobs-sulfur (mixotrophic) for treating the effluent from simulated urban wastewater plants

China's urban wastewater treatment plants' nitrogen discharge standards have become more stringent in recent years. In this experiment, the filled bed denitrification system with corncob-sulfur as fillers were constructed for the secondary effluent of the wastewater. The optimum operating conditions of the denitrification reactor with different fillers as electron donors were investigated by varying the operating parameters. According to the experiment, the alkali pretreated corncobs could maintain long-term denitrification effect. The optimum HRT for the mixotrophic denitrification reactor with alkali-treated corncob-sulfur as filler was 1.5 h, with a minimum effluent NO