Optimized Study On Further Nitrogen And Phosphorus Removal Of Jining Wastewater Treatment Plant

Since the 70th of last century,eutrophication has become a world-renowned environmental issue. Effective control of urban sewage nitrogen and phosphorus and other nutrient substances discharge is the most important way to solve the eutrophication problem. Sewage treatment plants mostly use the activated sludge process, and the removal effect of its nitrogen, phosphorus is not high effective. Therefore, most municipal wastewater treatment plant facing the task of nitrogen and phosphorus removal upgrade. The pape,combined with the actual situation of the Jining sewage treatment and upgrading needs, was emphasized on further nitrogen and phosphorus removal rates of the existing secondary sewage treatment plant. Experiments and researches were carried out on processing of town sewage by the MBBR activity sludge and composite ferric enzymatic activity sludge.1.The pilot study enhancing nitrogen and phosphorus removal with MBBR showed that:(1) In normal influent quality conditions,when organic loading rate was 0.865kgCOD/(m³·d),ammonia loading rate was 0.084kgNH₄⁺-N/(m³·d),HRT was 10.4h, suspendend carries filling rate was 67%,sludge return rate was 100%,aerobic mixture return rate was 200%,the COD,NH₄⁺-N,SS,TN and TP removal rates of MBBR syetem achieved 82.0%,92.6%,91.1%,46.3%,66.0%.The nitrogen and phosphorus removal rates were low for low carbon inffluent. During the test,the filling rate of suspendend carries decreased 17% had no greate negative impact on the MBBR system.(2) At high load conditions, when organic loading rate was 0.914kgCOD/(m³·d),ammonia loading rate was 0.103kg NH₄⁺-N /(m³·d),HRT was 8h, suspendend carries filling rate was 50%,sludge return rate was 100%,aerobic mixture return rate was 200%, the COD,NH₄⁺-N,SS,TN and TP removal rates of MBBR syetem were 81.6%,95.6%,90.9%,27.1%,47.3%,the test results showed that the MBBR system have stable endurance of carbon and ammonia shock load,and low concentration organic matter in influent still had impact on the removal rate of TN and TP.(3)Under adding caybon 33mg/l conditions,when organic loading rate was 0.900kgCOD/(m³·d), ammonia loading rate was 0.072kg NH₄⁺-N /(m³·d),HRT was 8h, suspendend carries filling rate was 50%,sludge return rate was 100%,aerobic mixture return rate was 200%, the COD,NH₄⁺-N,TN and TP removal rates of MBBR syetem achieved 81.7%,93.7%,70.3%,61.5%,the removal rate of TN and TP,compared with the conditon without adding carbon were increased by 36.4% and 7.5% respectively.At the same time,adding exogenus carbon source promoted the removal ability of refractory organic.(4) With low temperrature (16℃)test,,the contribution of suspended carries to syetem nitrification rate was 62.5%, MBBR process showed better resistance to low temperrature.2. The study enhancing nitrogen and phosphorus removal with composite iron enzymatic system showed that:(1) In normal influent quality conditions, when organic loading rate was 0.015gCOD/(gMLSS·d),ammonia loading rate was 0.015 gNH₄⁺-N/(gMLSS·d),aerobic reaction time was 5.2h, anaerobic reaction time was 5.2h,SRT was 15d, the COD,NH₄⁺-N,TN and TP removal rates of the composite iron enzymatic system were 78.8%,88.9%,55.0%,74.5%,the removal rate of TN was poor for the low carbon concentration in influent. With SRT extented to30d,the removal rate of COD,NH₄⁺-N,SS,TN and TP were 83.5%,94.9%,74.5%.(2) At high load conditions, when organic loading rate was 0.187gCOD/(gMLSS·d), ammonia loading rate was 0.016 gNH₄⁺-N(/gMLSS·d),aerobic reaction time was 4h, anaerobic reaction time was 4h,SRT was 30d, the COD,NH₄⁺-N,TN and TP removal rates of the composite iron enzymatic system were 80.1%,90.4%,40%,64.2%, and low concentration organic matter in influent still had impact on the removal rate of TN and TP.(3) Under adding caybon 33mg/l conditions,when organic loading rate was 0.205gCOD/(gMLSS·d), ammonia loading rate was 0.101gNH₄⁺-N/(gMLSS·d),aerobic reaction time was 4h, anaerobic reaction time was 4h,SRT was 30d, the COD,NH₄⁺-N,TN and TP removal rates of the composite iron enzymatic system were 85.8%,90.6%,69.6%,72.3%,the removal rate of TN and TP,compared with the conditon without adding carbon were increased by 29.6% and 8.1% respectively. At the same time,adding exogenus carbon source promoted the removal ability of refractory organic.(4) With low temperrature (16℃) test, the average nitrification rate of the composite iron enzymatic sludge was higher 15% than traditional activeted sludge.he contribution of suspended carries to syetem nitrification rate was 38%, the composite iron enzymatic system showed better resistance to low temperrature. To some extent, the composite iron enzymatic system can enhance microbial's biological activity to resist the changes of environmental factors outside.