Research Of Upgrading And Renovation Schemes In Secondary Wastewater Treatment Plants

Many wastewater treatment plants built up in the earlier time according to the thennational discharging standard adopted the advanced design theories. Stricter waterdischarging standard had to be taken as at that time the concerned national standardhad not been made and announced. But along with the urban rapid development，many wastewater treatment plants can not meet the new national dischargingstandard．Now，they are facing the problem of upgrading and renovation．This paper concerns about the preliminary researches of upgrading and renovationschemes in secondary treatment plants which emphases on the comparison anddetermination of the treatment process．For clearer explanation，the paper takesXianyanglu Wastewater Treatment Plant as an example in process upgrading.Through its process transformation，the plant is effluent to attain to the Grade Idischarging demand from the previous Grade II．In order to reach this objective，inaccordance with its influent quality and location，after many alternatives，finally aGrade IB water discharging process by enhancing biological nitrogen removal istaken, by transforming its bio-chemical process，for example disinfection，sludgeprocess and deozorization．After analysis and examination of the then conditions ofthe waste water disinfection system, sludge processing system and deozorizationsystem, only the deozorization system was transformed and upgraded, other systemsremained unchanged. This fully utilized the then available conditions and minimizednew investment.To maintain the same wastewater treating capacity and with the limited availableland, the plant was able to carry out the project of upgrading the treated water.standard. Such good renovation project is rare in China．Application of vertical ringoxidation ditch process in the transformation of the old wastewater treatment plant,should be an innovation of the subject.