The Experimental Research On Orbal Oxidation Ditch Process Function Upgraded Innovation

Weifang City Wastewater Treatment Plant adopts Orbal oxidation ditch process.Due to the improving of the sewage discharge standard by Weifang EnvironmentalProtection Agency, the process needs to upgrade to achieve “urban sewage treatmentplant emission standards”(GB18918-2002) Standard B of Class A.The processing based on the principles of maximum use of existing structures andfacilities，minimize the amount of reconstruction projects and beneficial to the futureoperation and management principles. More over, combine the Orbal oxidation ditchprocess characteristics of Weifang City Wastewater Treatment Plant，and take theadvantages of long age, strong shock resistance and stability of sludge，makes itpossible to do a overall transformation of the oxidation ditch. It proposed a program tostrengthen the feature of removing nitrogen and phosphorus, namely, the step-feed A/Obiological nitrogen removal&chemical phosphorus removal process. Then, a small scaleresearch for the key operational parameter of rehabilitation programs was carried on.The results shows that under the conditions of distribution ratio in the other water,dissolved oxygen in the1~2mg/L, sludge return ratio of75%, experiment hasachieved a good results. COD, ammonia and total nitrogen reached the standard B ofClass A. Yet the TP treatment has less effective shows that the process does not have thefunction of dephosphorization. And apply the chemical phosphorous removal process toachieve goals is necessary.In order to better analyze the step-feed A/O biological nitrogen removal processplus the feasibility of chemical phosphorus removal process，and provide the wastewatertreatment plant with various references in its actual operation，one oxidation ditch wasupgraded and compared with another one. Pilot studies have shown that， aftertransformation, step-feed A/O biological nitrogen removal process for differentpollutants have a commendable treatment effect. The quality and stability of the effluentwhich has a total phosphorus removal can reach the standard B of Class A. Bycomparing the rate of oxygen consumption，nitrification rate and denitrification rate,results show that, the sludge of step-feed A/O biological nitrogen removal process has a better activity. In order to achieve the phosphorus removal standard，beaker test andproduction test were carried on. And the results show that，by way of adding45mg/Lof PAC or ferric chloride, the total phosphorus can be reduced to1mg/L and bellow.In this study, the reconstructive programs for upgrading Orbal oxidation ditchprocess only needs a small amount of engineering to achieve the good effect, which isnot only convenient for future operation and management, but also provide the basic testdata for further production experiment. And it has a proper instructive significance forthe upgrading of Orbal oxidation ditch process.