Analysis On The Long-term Stable Operation Of O3-BAC Process

In order to make the tap water meet the national hygienic standard for drinking water and people's increasing demand for water quality,advanced treatment is widely used in water purification plants to ensure water quality.In this paper,a water plant in southern Jiangsu Province using Taihu Lake as a source of water is taken as an example to analyse the operation law of long-term stable purification of micro-polluted source water by O₃-BAC.By comparison test,study on the contribution of pre-ozone on removal of COD_Mnn was taken.Analyzing the removal efficiency of turbidity and oxygen consumption by pre-ozone and conventional treatment processes by study on run data of a water plant in southern Jiangsu,find that it can effectively control the organic matter content in the influent of advanced treatment process through improving the removal of turbidity by conventional process rate.For improve the removal efficiency of algae,we carry out KMnO₄ pre-oxidation test.we can determine the optimum dosage of KMnO₄ by study on the effect of different dosage of KMnO₄ on algae removal.Exploring the effect of pre-ozone process on reducing the odor of raw water,we can find that the removal rate of 2-MIB by pre-ozone was 32.38%when the pre-ozone dosage is 0.8mg/L and the main ozone dosage is 1.4mg/L.Increasing the dosage of pre-ozone can improve the removal efficiency of 2-MIB and decrease the concentration of 2-MIB in the effluent of subsequent stages,and make the concentration of effluent 2-MIB lower than the human olfactory threshold.Analyzing the removal efficiency of organic matter by O₃-BAC based on long-term run data of a water plant in southern Jiangsu Province.The results show that the removal rate of COD_Mn,TOC and UV₂₅₄ is the highest when O₃-BAC is just running,and then dropped rapidly in the following five months,then it showed a steady and slow downward trend in 6-24 months,maintain at 30%-40%,15%-25%,50%-65%levels respectively.In the middle period of 3-4 years'operation,the removal rate of COD_Mn,TOC and UV₂₅₄ by O₃-BAC is 30%-40%,15%-25%and50%-65%,respectively.During the long-term operation period of 5-7 years,the removal efficiency of COD_Mn,TOC and UV₂₅₄ by the advanced treatment remained stable,maintain at 15%-25%,10%-20%,30%-45%levels respectively.And the removal efficiency of ammonia nitrogen by O₃-BAC has been unsatisfactory,sometimes there is even a rebound.Analyzing adsorption performance of activated carbon based on long-term operation data.The iodine value of activated carbon fell 31.67%and the methylene blue value of activated carbon fell 20.66%within one year of operation of O₃-BAC.During 2-5 years of O₃-BAC operation,the iodine value of activated carbon fell 18.37%and the methylene blue value of activated carbon fell 45.56%.During 6-7.5 years of O₃-BAC operation,iodine value of activated carbon enters rapid decline stage again,the total decline was 40.36%,with an average annual decrease of 16.14%,and the decrease of methylene blue value is relatively small,the total decline was 32.61%,with an average annual decrease of 13.04%.Developing productive test of replacing long-running activated carbon filters after 6 years operation of O₃-BAC.Experiments show that in the first year after renewal,the decline rate of adsorption capacity of new carbon is obviously higher than that of old carbon when the water quality and quantity are the same.But the decline rate of adsorption capacity of new carbon slowed down obviously during1-1.5 years of O₃-BAC operation,the iodine value of activated carbon fell 4.19%and the methylene blue value of activated carbon fell 5.03%,and it means that the new carbon has entered a stable operation stage.