| This experiment mainly studied on chemical Phosphorus removal enhanced A2/O process to denitrification and phosphorus removal, namely enhanced biological nitrogen and phosphorus removal by chemical phosphorus removal. Biological treatment part adopts the A2/O process.Elected by chemical phosphorus removal small trial, the optimal chemical phosphorus removal Pharmacy and the best reaction conditions, based on the A2/O nitrogen and phosphorus removal system stable operation, Dos ing chemical Pharmacy in pre-chemical phosphorus removal tanks. Study the amount of chemical phosphorus removal influence on the subsequent biological process under the conditions of different lateral flow ratio’s.The oxidation ditch DO concentration in the range of3.26～4.55mg/L,1.73～2.74mg/L,1.12～1.50mg/L,the A2/O system has little effects on COD removal,COD removal efficiency more than90%. Total nitrogen, ammonia nitrogen and total phosphorus removal effect showed a trend of falling after rising first in three different DO concentrations, within the scope of integrated denitrification and phosphorus removal effect, oxidation ditch DO concentration was maintained at1.73～2.74mg/L for pollutant removal is more suitable.Respectively regulate nitrifying liquid reflux ratio r=1,1.5,2.0,2.5,3.0,4.0.COD concentration fluctuations between221～924mg/L,and although Water volatile,but the removal rate is over90%,nitrification liquid reflux has little effect on COD removal. With the increase of nitrifying liquid reflux ratio r, total nitrogen removal efficiency presents downward trend after rising first,when the reflux ratio was1.5, the system denitrification efficiency was the highest, when the reflux ratio more than1.5, the system denitrification efficiency into a downward trend. When the nitrification liquid reflux ratio r were1,1.5,2.0, ammonia removal efficiency is high, at more than90%, when the nitrifying liquid reflux ratio r of2.5,3.0,4.0, ammonia nitrogen removal rate to decline. When the Nitrification liquid reflux ratio r=1,1.5,2.0,2.5,3.0,4.0,the average removal rate of total phosphorus presents the trend of increased and then decreased, when nitrification liquid reflux ratio r=1,2.5,3.0,4.0, phosphorus removal was low,and the average effluent concentration greater than1mg/L,Integrated nitrogen and phosphorus removal effect and economic considerations, choice nitrification reflux ratio r=1.5is appropriate.Respectively regulate the sludge reflux ratio R of0.75,1.0,1.5.It has little effect on COD removal,the removal rate of more than90%.The total nitrogen removal rate increases with the increase of sludge reflux ratio,when adjusting the sludge reflux ratio R=1.5,total nitrogen removal works best.Regulating sludge return ratio, has little effect on the removal of ammonia nitrogen, the removal rate of about92%.Adjustthe sludge reflux ratio, total phosphorus removal efficiency is increased and the sludge reflux ratio decline, The removal rate reduced to84.17%from90.33%. Integrated the removal of various pollutants, the selection of sludge reflux ratio R=1.0is more appropriate.COD concentration in the range of323mg/L～1041mg/L.COD removal efficiency was stable, the average removal rate was93.13%, the water carbon source had a little effects on COD removal; TN, ammonia nitrogen and TP removal rate has a certain relevance with concentration of COD, as the water COD concentration changes, the removal rate was corresponding increase or decrease,In three temperature condition, the working condition of1, the temperature is greater than20℃; Condition2, temperature between15～20℃; Condition3, the temperature is less than15℃. The average removal rate of COD were91.47%,93.77%and91.10%, the temperature effect on COD removal efficiency is little. The average removal rate of TN were72%,66.07%and53.63%. The average NH3-N removal rate were84.30%,85.50%and37.2%. The average removal rate of TP were94.25%,93.30%and82.90%, respectively. Temperature has effect on the removal rate of total nitrogen, ammonia nitrogen and total phosphorus.Using calcium hydroxide, polyaluminium chloride, aluminium sulphate and ferric chloride test in four kinds of chemicals for chemical phosphorus removal. The same chemical dosing quantity, polyaluminium chloride on phosphorus removal effect is better than calcium hydroxide, ferric trichloride and aluminum sulfate.But the price of aluminium chloride is higher, choose magnesium chloride as dephosphorization agent. In five different working condition of side flow ratio (0%,5%,10%,5%and10%), the system for pollutant removal efficiency has a great influence. Along with the increase of the side flow, the phosphorus removed through chemical methods was more, make the follow-up biological treatment unit get a higher C/N ratio, TN removal rate increases with the increase of the ratio of side flow ratio; When side flow ratio varying from0%to30%, the TP removal efficiency was decreased after rising first,the removal rate is99.5%when the side flow ratio is10%,the removal rate of TP after began to fall, when the lateral flow ratio is30%, fell to82%,the TP is not up to level of A water standard. Comprehensive TN and TP removal efficiency and economical efficiency, selection the side flow ratio is10%. |
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