The Analysis And Upgrading Of A Carrousel Oxidation Ditch Process In Kunming

With the acceleration of urbanization and rapid economic development, urbansewage treatment faced a severe test. Especially since the country launched of pollutiontreatment from the "three rivers"(the Huaihe, Haihe and Liaohe),"three lakes"(Taihu,Chaohu and Dianchi Lake) watershed and the "Bohai" region, our country has increasedgovernance of these basins efforts, so that water environmental quality of these basinswere more stringent, the national " Urban sewage treatment plant pollutant dischargestandard "(GB8978-2002) B up to A standard mark. Meanwhile, under background ofthe national "12ï¹'5" to develop energy conservation policy, How to solve the existingmunicipal wastewater treatment plant operation problems that existed in higher energyconsumption, optimized to run on how to carry out energy-saving and emissionreduction of the sewage treatment plant was worthy of study. Based on the abovesituation, a resolution and propose appropriate rehabilitation programs were proposedfor a Carrousel oxidation ditch process in the Kunming Dianchi Lake basin.Throughmonitored a sewage treatment plant along the Carrousel oxidation ditch process inKunming. The results showed that the high concentration of the effluent TN and therewas the phenomenon of excessive,its annual average concentration was14mg/L, theeffluent NH3-N had the phenomenon of excessive and fluctuations, NO2-N and NO3-Nhad low concentration along the water and their concerntration were0.11mg/L and3.49mg/L. Most of the effluent TN was constituted by NH3-N and NH3-N accounted for73%of TN in water. To the above problems, analyzed some factors that led to sewagetreatment plant water NH3-N was high. Through monitored the Carrousel oxidationditch’s horizontal, vertical dissolved oxygen (DO) found that the oxidation process DO was low along and vertical0.5meter almost had no DO, most regions were hypoxicenvironment. The reason for the phenomenon was that the surface aeration equipmentsof the sewage treatment plant was old led to low efficiency, thereby inhibiting theoxidation of NH3-N, and led to seoondary treatment of the sewage treatment plant hadhigh energy consumption its0.442KWï¹'h/m3. Determined nitrification rate inOxidation ditch found that ammonia degradation rate was0.047(NH3-N) Kg/d Kg(MLSS), nitrite degradation rate was0.029(NO2-N) Kg/d Kg (MLSS), the generalrate was less than the activity of nitrifying bacteria in sewage treatment plants(Degradation rate of the general sewage treatment plant was0.09~0.2Kg/d Kg(MLSS)).Through analysised influent carbon to nitrogen ratio was between4~8(COD/TN)in the sewage treatment plant found that influent carbon source was fluctuated.Influentcarbon component was measured for making full use of limited carbon.The results showthat total organic influent concentration was about150~630mg/L, the averageconcentration was300mg/L, in which particulate organics was about70~330mg/Laccounting for45%~52%; dissolved organic solubility was about60~300mg/L,accounting for40%to48%; readily biodegradable organic matter accounted for10%to20%of organic matter, slow biodegradable organics accounted for40%to60%. Proteinaccounted for23%of the total organic matter in the water, polysaccharides onlyaccounted3%. Since the oxidation ditch was a relatively closed ditches, its distributionwithin the flow pattern and pollutant are closely linked. To this end, this paper exploredthe relationship between the flow pattern and pollutant distribution in oxidation ditch,the result showed that DO was proportional to the flow velocity, MLSS was inverselyproportional to the flow velocity, TP and DO distribution had closely linked, butbecause of the lower DO state NO3-N and NO2-N had no obvious connection.To solve the above issues raised rehabilitation programs: using the bottom ofmicroporous aeration replaced the surface aerator to enhance aeration efficiency andforming a changing speed’s oxidation ditch through opened a hole and unchanged theoriginal infrastructure. In order to achieve oxidation ditch pollutants efficientlydegradation and energy saving.Carrousel oxidation ditch process was test run and debugged and out of water and energy consumption were monitored and calculated after completion of the renovationproject,the result showed that effluent NH3-N has largely reduced compared to beforeand the average effluent concentration was0.61mg/L, the average effluent NO3-Nconcentration was9.75mg/L, the effluent TN average concentration was11.08mg/L.Treated water stability of "urban sewage treatment plant pollutant dischargestandard"(GB8978-2002) an A standard, the secondary treatment unit energyconsumption has decreased from0.442KW.h/m3down to0.2526KW·h/m3,energy-saving effect is very significant.