| It is a long time for lakes and reservoirs used as the source of drinking water. The water will be easily contained, and even can’t reach the standards, endangering the livelihood security of the people in this completely open system due to human activities and the natural environment. Disinfection by-products will change with the amount of organic matter in water. USEPA proposed the concept of disinfection by-products formation potential to characterize the relationship between organic matter and water disinfection by-products. The amount of disinfection by-products generated in subsequent treatment process will be directly determined by the level of disinfection by-products formation potential in source water. As the main surface water reservoir in Xi’an, Heihe is a type of thermal stratification and deep-water reservoir.It is instructive for taking reasonable control measures in subsequent treatment of drinking water to survey the disinfection by-products formation potential change under different natural or human activities conditions in the reservoir, such as thermal stratification, rainfall runoff and the running of the water-lifting aerator.Studied the changes of characteristics of organic matter and disinfection by-products formation potential before and after the thermal stratification, rainfall runoff and the running of the water-lifting aerator in Heihe reservoirs ——the main surface water reservoir in Xi’an. Water quality analysis was conducted at the reservoir site and school laboratories. The main conclusions are as follows:(1)In the completely mixed(January to March) in Heihe reservoir, it changes little for temperature and dissolved oxygen. The water has a high content of DOC due to the release of the endogenous pollutants in water. Epilimnion, thermocline, thermostatic layer appeared during the thermal stratification(May to July).In the initial of the stratification, the content of DOC was reduced, due to the organic matter was extensive used by the anabolic of microorganisms. The content of humic acid was increased.TCMFP was lower than it in the early completely mixed, haloacetic acids increased rapidly after the stratification. The DBPs was increased from 160~375 μg·L-1to 280~630 μg·L-1.The level of the disinfection by-products formation potential was changed from TCMFP>TCAAFP>DCAAFP to TCAAFP>TCMFP>DCAAFP.(2)Rains broke the original layered structure, the temperature difference between the surface and the deep of the reservoir fell as much as 5.0 ℃,water at 20~80 m was remixed. Because of a lot of nutrients from the upstream was carried to the reservoir during the rainfall and the rainfall runoff, the pollutants was accumulated and the content of DOC was increased 0.9 mg·L-1. Both the content and the proportion of aromatic substances were increased. Each disinfection by-products formation potential is higher than them before the rainfall, especially for the dichloroacetate. The level of the disinfection by-products formation potential was changed from TCAAFP>TCMFP>DCAAFP to TCMFP>DAAFP>TCAAFP.(3)Water will be mixed due to the running of water-lifting aerator,then the difference of temperature and the content of dissolved oxygen between the surface and the bottom of the reservoir is lower than them before it runs. The decomposition of organic matter was promoted and the content as well as the proportion of the DOC and the aromatic substance in water was reduced due to the oxygenation. The DBPsFP decreased 50% a month later. The level of disinfection by-product formation potential follows TCMFP> TCAAFP> DCAAFP.(4)Analyzed the relationship between the characteristics of organic matter and disinfection by-product formation potential, it was found that there has a There was a good correlation between DOC, SUVA,- △ UV272 with haloacetic acids,total disinfection by-products except chloroform. It has a certain correlation between ФⅤ,n and chloroform, haloacetic acids and total disinfection by-products. Overall, the indexes of organics described above can be uesd as indicators to measure the level of disinfection by-products formation potential. |
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