Advanced Treatment On Tail Water From Municipal Wastewater Treatment Plant By Modified Diatomite

In order to alleviate the growing intensified water crisis, under advanced treatment, the reuse of tail water from municipal wastewater treatment plant has been put into important practical significance. Using diatomite for sewage treatment is a new technology. However, the application of this technology is mainly taken in treating most types of industrial wastewater and urban sewage, rarely applied on advanced treatment, and relevant reports about it are also limited.Based on this point, the topic broadened the application field of diatomite and enhanced experimental study on modified diatomite for tail water from municipal wastewater treatment plant by advanced treatment.The research included the determination of the modification method of diatomite, the study on removal ability of pollutants of modified diatomite, the optimization of operating condition and summary of the utility data of modified diatomite that treated tail water from municipal wastewater treatment plant. Through this research, it can provide data which supports the technology used in advanced treatment for tail water from municipal wastewater treatment plant and offer practical reference and basis for the follow-up research. The results showed as follows:(1)The study on composition modification of diatomite showed that the removal efficiencies of composited compound 6-3 for CODCr, TP, Ammonia Nitrogen from tail water were the most ideal, so we determined to apply composited compound 6-3(PAC: ferric chloride:Sodium lime:diatomite=25%:5%:6%:64%) for the future research.(2)From the study on removal ability of pollutants of modified diatomite,we found that removal ability of modified diatomite for pollutants was strong,and the optimal dosage of modified diatomite was 50 mg/L when it was used to treat raw water, then the average removal efficiencies for CODCr,TP,Ammonia Nitrogen and TN from raw water were 66.3%,80.2%,18.9% and 29.1% respectively,the removal efficiencies were relatively ideal, which provided a scientific basis for accurate quantitative analysis on the results of treatment for tail water from municipal wastewater treatment plant by modified diatomite.(3)When the modified diatomite were used to treat tail water from municipal wastewater treatment plant, the optimal dosage of modified diatomite was 30 mg/L, the best influent flow was 34 L/h (residence time was about 2.Oh), and the best mechanical stirring speed was 45 r/min.In this case, the average removal efficiencies for CODCr,TP, Ammonia Nitrogen and TN were 49.2%,67.8%,38.7% and 24.2% respectively, the removal efficiencies were ideal.