Study On Optimization And Upgradation Of Sewage Biochemical Treatment

Taking the field operation of a certain wastewater treatment plant in Xiangtan and its excess sludge as the object of the research. Many problems in wastewater biochemical treatment have arisen, for instance, its sewage are sometimes difficult to reach A standard?GB18918-2002?, lack of carbon and would require the additional carbon source, excessive sludge's treatment and disposal problems, etc. Optimization and upgradation of sewage treatment were studied . The research is aimed at making wastewater discharging standard and sludge reduction for the problem of insufficient carbon source.Combined with the field process and the operational test data, it was deduced a mathematical model ?=KXt/1+KXt=6.32*10^-3xt/1+6.32*10^-3Xt which reflected the relationship between the removal rate ? of organic matter and the kinetic parameters--organic degradation rate constant K, activated sludge concentration X and hydraulic retention time t. According to the mathematical model, it was shown that the removal rate of organic matter could be predicted satisfactorily by the mathematical model and the industrial production could be guided by the prediction.Taking the residual sludge as the research object and the organic matter?COD? of the sludge supernatant as the index, the research investigated the influence factors of ozone and alkali treatment on sludge. Such as pH, ozone and alkali dosage, time and temperature.The result showed that sludge disruption under ozone or alkali treatment can product acid then reduce the value of pH. Under the value of pH is 11, the ozone dosage is 4.41g/gSS, sludge concentration is 14376.2mg/L. Ozone treatment method, the value of COD in sludge supernatant fluid reached about 500mg/L. Under the alkali dosage is 0.039gNaOH/gSS, the processing time is 28 hours, the temperature is 12? . Alkaline hydrolysis COD in sludge supernatant fluid is more than 650mg/L.Taking the value of COD, the removal rate of volatiles suspended solids?VSS? and the cost as the index , the research compared and analyzed the two methods of ozone and alkali treatment. The technical comparison result showed that the value of COD/gVSS of alkali treatment is about 2.3 times than that of ozone treatment. And the removal rate of VSS is about 1.4 times than that of ozone treatment. The economic comparison result showed that the cost of ozone treatment is about 467.5 yuan/m³ and alkali treatment is simple ,low cost only 0.83yuan/m³. Comprehensive comparison of both, alkali treatment sludge has the advantages of high efficiency and economy.The orthogonal experiment and the optimization experiment showed that the optimum technical conditions as follows: the alkali dosage is 0.052gNaOH/gSS, the temperature is 25?, magnetic stirring for 1 day. Under the experimental conditions, the value of BOD₅/COD is about 0.71 greater than 0.3, the value of C/N ?BOD₅/TN? is about 33.79 much greater than 4. Indicating that the sludge reduction after alkali treatment , the supernatant fluid is easy bio-oxidisability. Consider it return to the biochemical pond to supplement the lack of carbon sources.