Research on Variation of ORP on Operation Period of SBBR One-Stage Completely Autotrophic Nitrogen Removal System

To explore the feasibility of ORP as the control parameter of one-stage completely autotrophic nitrogen removal system, this test studied the synthetic low C/N waste water, analyzed the correlation between the variation rule of concentration of ORP and the transfer of nitrogen compounds in system under different concentrations of DO. Results indicated that the ORP curve emerged a turning point when transfer of ammonium finished under the conditions of DO concentrations were 2.0 mg/L and 1.5mg/L respectively, later the rise speed slowed down, at this point TN removal rates were 69.7% and 81.1% respectively in the system; there was no feature points when DO concentrations were 1.0 mg/L, because ammonia has not been completely transformed in a reaction cycle. Test under different concentrations of DO verified further the reproducibility of characteristic points of ORP, revealing that ORP can serve as the control points to judge completion of the transfer of ammonium consequently stopping aeration.