Study Of Hollow Ceramic Sphere Filter Media In Biological Aerated Filter

With the development of industrialization and expansion of population,the problem of water pollution and water scarcity is becoming increasingly serious. Biological Aerated Filter is an attractive wastewater treatment technique with the advantages of economics grounds,high treatment efficiency and easy operation,will be one of the important technical approaches to solve the water crisis situation of china. However,its development is limited in our country due to the shortage of the filter media research.Hollow ceramic sphere filter media was the core term in this dissertation.First of all,its' properties and microscopic structure were detected.Then,hollow ceramic sphere was applied to Biological Aerated Filter to treat domestic wastewater.In this section,the growth of biofilm and the factor of gas-water ratio and hydraulic loading to influence the removal effect of pollutants were studied.In addition,the method,intensity and period of backwash were also discussed.The results indicated:(1) The detection of properties and SEM photos showed that the specific surface area of hollow ceramic sphere filter media was up to 3.25m~2/g and the micropore rate was 54.8%.The results also showed that the surface was very rough and had many small holes.Besides,it can effectively resistance to the acid and pressure.All of these advantages showed that the hollow ceramic sphere filter media was fit for the requirements of biofilm carrier.(2) Hollow ceramic sphere was used as filter media in this experiment.It taked about 11 days to succeed in the growth of biofilm and the removal of COD,ammonia nitrogen gets to 75%and 60%.The experiment indicated that hollow ceramic sphere filter media played a good role in biofilm carrier.(3) The Up-flow Biological Aerated Filter was designed during the experiment. The influence of gas-water ratio and hydraulic loadings on effluent was studied and the main pollutants removal law was analyzed.The experimental results showed that the average removal of COD,ammonic nitrogen and suspended substances were all over 80.6%when the gas-water ratio in the range of 5:1-7:1.The result on studying the hydraulic loading influence the removal efficiency showed that when gas-water ratio at 7:1,hydraulic loading from 0.3m~3/(m~2.h) to 1.0m~3/(m~2.h),the removal efficiency of COD and suspended substances descended slightly.However,the removal efficiency of ammonia nitrogen descended sharply.(4) The method,intensity,and period of backwash were all studied in experiment, results showed that:the method of using air scouring firstly,then air-water backwashing, and adopting water-wash finally had many advantages over other methods.Backwash parameters summarized were:air scouring intensity was 10L/(m~2.s),duration was 3min; air intensity,water intensity and duration of air-water backwashing was 10L/(m~2.s), 8L/(m~2.s) and 5min respectively,at the end of the process,single water-washing intensity was 8L/(m~2.s),duration was 10min.Several validation showed the backwash as before was good enough.