Research On The Controlling Method Of Disinfection By-Products In Water Treatment

Taizhou is a typical city with quality-induced water shortage.The distribution of water resources in Taizhou has the following main characteristics:uneven distribution of time and space,and unmatched precipitation with urban areas.How to develop and utilize water resources efficiently and safely according to its environment and characteristics,has been a major issue that all the water engineers in Taizhou are concerned about.Disinfection process--an important part of water treatment process with its function of continuously killing pathogenic bacterial,virus and microorganisms,is the core process of water-quality safety.But the disinfection by-products accompanying the chlorine disinfection process,which are found to be seriously harmful to human body,should be controlled.By collecting and analyzing some basic data and technological processes of some major and medium-sized water plants in Taizhou,and did comprehensive comparison of several disinfectants,we decided to modify by using the sodium chloride instead of liquid chlorine,and set up a corresponding dosing system,the dosage and dosing mode of disinfectant,in order to improve the disinfection effect and effectively control the production of disinfection byproductsAccording to the current situation of a medium-scaled water plant in Taizhou,we collected a four months’ water samples(collected in the same period of time during the year)from the water plant for two years and had them tested.And then we compared and analyzed the testing results,which showed that the conventional indicators such as residual chlorine and turbidity improved slightly after the innovation,with 5.7%increase in residual chlorine and 8.2%decrease in turbidity.The two representative indicators of chlorine disinfection by-products,chloroform and carbon tetrachloride,were obviously controlled after the innovation,with 43.3%reduction in chloroform and 22%decrease in carbon tetrachloride.This shows that innovation of using sodium hypochlorite instead of liquid chlorine can effectively control the generation of disinfection by-products.By comparing and analyzing the costs of two disinfection systems,the disinfection cost per ton of water with liquid chlorine was 0.016234 yuan before modification,while the disinfection cost per ton of water with sodium hypochlorite was 0.015961 yuan after modification.There is an reduction of the cost by 1.68%.Assuming a water plant producing 75,000 tons of water per day,the total annual cost of disinfection with sodium hypochlorite will be reduced by 7464.64 yuan.After the innovation,the disinfection by-products are controlled,the operation and maintenance are simplified,the production safety is improved,while the costs of disinfection was reduced,the advantages are outstanding.In conclusion,the innovation of sodium hypochlorite disinfection system is positive.Not only it can reduce the total cost,but also can effectively control the production of chlorine disinfection by-products,greatly guarantee the safety of drinking water.Meanwhile this innovation has high promotion value,really suitable for some other small or medium-scaled water plants referencing.