Study On Denitrification And Phosphorus Removal Effect Of Small Urban Wastewater Treatment Plant In Winter

In this paper,the effects of the integrated equipment on the removal efficiency of nitrogen and phosphorus at low temperature conditions in winter were studied in a small town waste water treatment station.The work included three parts as below:adjustment of operational parameters,two-monomer series and chemical phosphorus removal:1.Adjustment of operational parameters:the effect on the reactor treatment rate is studied by the reactor HRT,the dissolve oxygen concentration,and whether there is carbon source in inlet.The results show that.?1?The average removal efficiencies of effluent NH₃-N?TN?TP from 50.4%?35.4%?42.8%increased to 69.3%?43.3%and 45.3%under the condition of HRT=4h extend to HRT=8h when DO=2.0?3.0 mg/L.This experiment shows that the removal efficiencies of effluent NH₃-N?TN?TP was improved when extend the HRT,while the removal efficiencies of TP was not obvious.?2?Controlling the volume of water when HRT=8h,under the condition of DO=0.8?2.0 mg/L,the average removal efficiencies of effluent NH₃-N?TP?TN were 61.6%?47.3%?62.2%;when DO=2.0?4.0 mg/L,the average removal efficiencies of effluent NH₃-N?TP?TN were 65.7%?41.9%?33.3%.It illustrates that the removal efficiencies of pollutants were not obvious with the change of DO.?3?The average removal efficiencies of effluent COD_cr?TN were 89.0%?16.4%when no external carbon source was added,the average removal efficiencies of effluent COD_cr?TN were 81.8%?43.2%when use solid sodium acetate as external carbon source.The results show that the removal efficiencies of TN was improved when add carbon source.2.Two-monomer series:In series with two integrated bioreactors to form a two stage biological process.the results shows that the average removal efficiencies of effluent NH₃-N?TP?TN were 1.6%?47.3%?62.2%when the DO=2?4 mg/L at the first stage reactor.Under the anoxic condition of the two stage reactor(DO=0.3?0.8 mg·L^-1),the average removal efficiencies of effluent NH₃-N?TN were 93.7%?83.1%while the removal effect of TP is not obvious.This experiment shows that the removal efficiencies of effluent NH ₃-N and TN was improved when two-monomer series,while the further test was necessary for the removal of TN.3.Chemical phosphorus removal:The method of chemical phosphorus removal was used to screen coagulant?adding point and adding method.The average removal efficiencies of effluent TP was 77.3%after 30 days of operation,and the effluent can come up to the first level B standard of“Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”?GB18918-2002?.The experiments of this paper solved the problem of ultra-high concentration wastewater under low temperature conditions in winter,and it has certain engineering value.