Experimental Research On Upgrading Of Iceas Sewage Treatment Process

As we all know, Wastewater treatment of urban sewage treatment plant existed theproblem of low carbon-nitrogen ratio, which making wastewater treatment plant cannotachieve efficient nutrient removal function. Through the distribution of the influent flowto each reaction stage，Step feed process achieve a rational use of carbon in raw water，so that it is possible for the wastewater treatment plant to improve nitrogen removalefficiency. This study focused on the application of SBR intermittent influent process inICEAS sewage treatment process upgrade, hoping to achieve5%increase of totalnitrogen removal efficiency without adding carbon source, thereby reducing the organicload discharged into the river. Combined with problems in the actual operation of thesewage plant production, based on treatment of actual wastewater, this paper analyzedthe methods to improve efficiency of the wastewater treatment from four aspects: wayof influent, ratio of drainage, operation mode and time of denitrification.Firstly, SBR reactors were used in these comparative experiments to study thechanges of nitrogen removal efficiency when the way of influent and ratio of drainagewere changed. The results showed: intermittent operation mode avoided consumption ofcarbon source in wastewater under aeration phase, so that more carbon source can beused in denitrification which could increase the efficiency of nitrogen removal, thenitrogen removal rate of6h/cycle intermittent operation mode increased by20%compared with the original mode, while total nitrogen concentration in effluentdecreased7mg/L; the nitrogen removal rate of4.8h/cycle intermittent operation modeincreased by8%compared with continuous feeding mode, total nitrogen concentrationin effluent decreased2.4mg/L. In addition, when drainage ratio varied between20%to40%under4.8h/cycle mode, three stages were separately compared, it was found thatthe TN removal efficiency was increased as the rise of drainage ratio in each stage.However, when the ratio was35%and40%, the concentration of ammonia in effluentwas largely increased. Therefore, the optimum drainage ratio was30%.Secondly, monitoring the entire process on ICEAS reaction tank and reactorssimulated the original process mode, can be seen that the drainage contained highconcentrations of nitrate nitrogen, denitrification process was hardly occurred in thesecond mixing process of the original operation mode for stirring twice and aeration twice, in this phase DO>0.5mg/L while hypoxic environment cannot be formed,therefore, transformed operation mode for stirring once and aeration once could increasethe TN removal efficiency. Using pH and ORP instruments monitored the reactionsystem during their operation, in order to observe significant changes in pH and ORP.Comparative studies have shown that: even carbon of influent was enough, stirring48min and56min couldn’t finish denitrification under continuous feeding mode, soincreasing the ratio of mixing time and aeration time(A/O ratio) could enhancedenitrification, when A/O ratio≤1:1, the total nitrogen removal elevated with the A/Oratio becomes large, and the nitrogen removal of intermittent mode was more efficientthan continuous mode, when the A/O>1:1ammonia concentration in water were5~10mg/L, therefore, stirring78min and aeration90min was more reasonable.Finally, comparative tests were carried out to verify the conclusion by SBRreactors through constructing pilot reaction tanks which had cell geometry similar withICEAS reaction tank, during debugging issues of insufficient nitrification capacity wasfound, through replacing the aeration plate to strengthen the nitration effect of thereaction system; when drainage ratio was17.6%,24.3%, and21.7%, compared resultsof nitrogen removal between the original process mode and the improved model ofintermittent feeding mode, TN removal of intermittent feeding mode increased by4%to5%, the averaged total nitrogen concentrations in effluent was10mg/L.