| In recent years, the type and concentration of micro-organic pollutants increased rapidlyin Huaihe raw river,traditional treatment methods were difficult to effectively removemicro-pollutants and pathogens in polluted water sources.Water quality safety and biologicalstability were not guaranteed, So it's particularly important and urgent to carry out researchon advanced treatment technology of Huaihe raw water. According to the water quality characteristics of Huai River basin's Tongyu river andYanlong river, a drinking water pilot plant based on ozonebiological activated carbon processwas designed. This paper mainly contains as follows:firstly, quality investigation of watersource. Secondly, designing and debugging of the pilot plant. Then, the biological contactoxidation and preozonation operation optimization,and the influence on trihalomethane formation. At the same time, comparing the different pollutants removal effect between process 1and 2. Finally, Improving ozone biological activated carbon process, observing the waterbiological stability and analyzing the pollutant removal mechanism in water. After investigating the water quality of Tongyu river and Yanlong river, it was found thatraw water turbidity in Yanlong river decreased year by year between 2010 and 2015. Thewater have the highest turbidity in July and August and the lowest in winter. However, waterquality exceeded surface water Class III water standard (GB3838-2002) even though CODMndescended every year. As for Tongyu river, both water turbidity and CODMn had an increasingtrend. The concentrations of ammonia nitrogen, TN and TP showed a decreased tendency inYanlong river which were just the opposite in Tongyu river. Through the study of biological contact oxidation pretreatment, When HRT was 2 h, gaswater ratio in (1-1.2):1, CODMnand ammonia nitrogen removal rate were 16.64%and47.16% respectively. Combined with organic matter removal during the period of hangingbiofilm, it was observed that the molecule weight of organic matters were less than1000 Dalton had a better removal efficiency, Biological contact oxidation pretreatment couldeffectively reduce the THMFP, trichloromethane and bromodichloromethane removal ratewere 17%and 12%respectively. Based on the research of pre-ozonation, determine the ozone dosage was 0.5 mg/L,ozone residence time was 5 min, The removal rate of CODMn and UV254 were 28.21% and32.89% respectively. DOC and BDOC growth rate were 20.89% and 22.14% respectively,decreased the water biological stability, But help the follow-up biological activated carbon onthe degradation of organic matter removal, pre-ozonation had a low removal efficiency ontrichloromethane, tribromethane, bromodichloromethane,dibromomethane,which removalrates were 9%,4.67%,8.98% and 10.57%, respectively. This may be due to the lower content of bromide, and low levels of organic precursor.Inspection process 1 and process2 removal efficiency of pollutants in water, the results showed that process 1 had better removal fficiency on CODMn, ammonia nitrogen, DOC, BDOC and disinfection by-products and their precursors.but process 2 had better removal rate on UV254, But may cause the concentration of ammonia nitrogen, DOC and BDOC rising, improving the water biodegradability. So, pre-ozonation and biological activated carbon (BAC) filter always combined to ensure the biological stability of water quality.In advanced treatment process, ozone-activated carbon process was adopted.the study found that when the ozonation contact time was 10 min, ozone dosage increased from 1.2 mg/L to 2.0 mg/L, the removal efficiency of CODMn and ammonia nitrogen increased 5.45% and 10.3% respectively. Ozone dosage had little effect on TOC removal efficiency, whereas the DOC and BDOC increased 20% and 111.65% respectively,This showed that ozone oxidation increased DOC concentration, removal efficiency of Ozone dosage on THMFP was studied.found that the trichloromethane and bromodichloromethane had better removal efficiency than tribromethane and dibromomethane. From the view of process optimization, 1.2 mg/L?2.0 mg/L of ozone dosage was more appropriate.Investigated the contaminant removal effect of biological activated carbon filter, When the filter speed between 6?8 m/h, EBCT was 15 min and the carbon layer depth between 0.9 m and 1.5 m, the removal efficiency of CODMn, UV254 and ammonia nitrogen were best. With the increase of carbon layer depth, the removal rate of TOC and DOC were showing a rising trend, the highest removal rate were 42.95% and 66.56%, respectively, BDOC effluent concentration always below 0.35 mg/L, The study found that advanced water treatment process had better removal efficiency of trichloromethane, tribromethane, bromodichloromethane and dibromomethane were 17.83%,8.79%,12.83% and 17.83%, respectively. it was important to the reduce of THMFP and improvement of water biological stability. |
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