Treatment Of Reject Water From Wastewater Treatment Plant Using SBR

The reject water produced within WWTP is characterized with small flow rate, high concentration of ammonium and phosphorus and low biodegradability.So far most WWTPs the reject water returned into the inlet or retreated with influent. Treatment of reject water from WWTP using SBR was investigated.The system was operated 381 days under three different(A/O)_T(retention time ratios of anoxic to oxic)conditions:0.2,0 and 0.5.During the entire operation of the SBR system,the influent TCOD concentration ranged from 594 to 1333mg/L and NH₃-N from 361 to 727mg/L.As the results showed,69-76%TCOD,99.0%NH₃-N and 26.0-34.9%TN removal were achieved in the SBR reactor.When(A/O)_T was 0.2 with 30h of HRT and 18.7d of SRT,the experiment results showed that 76%TCOD,99.0%NH₃-N,34.9%TN removal was reached at 594mg/L and 415mg/L of the average influent concentration of TCOD and NH₃-N;When (A/O)_T was 0 with 30h of HRT and 7.1d of SRT,the experiment results showed that 69%TCOD,99.0%NH₃-N,26.0%TN removal was reached at 1143mg/L and 590mg/L of the average influent concentration of TCOD and NH₃-N;When(A/O)_T was 0.2 with 40h of HRT and 6.2d of SRT,the experiment results showed that 74%TCOD, 99.0%NH₃-N,27.8%TN removal was reached at 1333mg/L and 447mg/L of the average influent concentration of TCOD and NH₃-N.So the reactor had steady treatment effect.Nitrogen in SBR is removed by three pathways:biomass synthesization,anoxic denitrification and oxic denitrification with fractions of 8.0-15.1%,9.2-12.5%and 76.8-84.9%,respectively.So,oxic denitrification plays an important role in Nitrogen removal.Under the experimental conditions,DO,PH and ORP had good pertinence with nitrification process in a cycle.