Study On The Removal Characteristics Of Chlorine Disinfection By-products By Activated Carbon In Drinking Water

Research on chlorine disinfection by-products such as trihalomethane(THMs)and haloacetic acid(HAAs)has become a hot topic in the field of drinking water safety.Long-term drinking of drinking water containing chlorine disinfection by-products will affect human physical and mental health.In view of this background,the by-products of chlorine disinfection in drinking water in typical cities in China were investigated.Then a series of experiments were carried out to analyze the effect of activated carbon in controlling chlorine disinfection by-products.Finally,a small household water purification device was designed based on the experimental results.The main results were as follows:1.In 35 typical cities,the concentration of CHCl3 in drinking water ranged from 0 to 10?g/L in 5 cities,10 to 30?g/L in 18 cities and 30 to 60?g/L in 12 cities.There were 27 cities where the concentration of CHBrCl2 was in the range of 0-10?g/L and 8 cities higher than 10?g/L.The concentrations of CHBr2Cl and CHBr3 in drinking water in 35 cities were lower than 10?g/L.There were 31 cities with CI2CHCOOH concentration ranging from 0 to 10?g/L,4 cities higher than 10?g/L.There were 32 cities with Cl3CCOOH concentration ranging from 0 to 10?g/L,and 3 cities higher than 10?g/L.2.At low concentration,the adsorption of CHCL3,CHBrCl2 and Cl2CHCOOH by activated carbon complied with quasi-second-order adsorption kinetics model and Freundlich adsorption isotherm model.When adsorption system changed from binary adsorption to ternary adsorption,the adsorption capacity of three chlorine disinfection by-products within 2h decreased by 9.6%,5.9%and 11.4%,respectively.The effect of experimental temperature on the adsorption of three chlorine disinfection by-products by activated carbon was not significant.With increase of concentration from 0.5 times to 2 times the national standard limit,the adsorption rates of three chlorine disinfection by-products increased by 0.77?g/(L min),0.49?g/(L min)and 0.41?g/(L min),respectively.The change of cationic concentration in the system had little effect on the adsorption of three chlorine disinfection by-products by activated carbon,while the presence of humus in the adsorption system would significantly affect the adsorption of three chlorine disinfection by-products by activated carbon.The presence of humus in the adsorption system reduced the removal rate of three chlorine disinfection by-products by activated carbon by 9.87%?19.44%.3.Activated carbon adsorbed three chlorine disinfection by-products mainly through its specific surface area and micropore density.The surface functional groups of activated carbon have some influence on HAAs adsorption by activated carbon,but had little influence on THMs adsorption.Compared with K and N values in adsorption thermodynamic model,the adsorption capacity of activated carbon on three chlorine disinfection by-products were CHBrCl2,CHCl3 and Cl2CHCOOH in turn.4.In the dynamic penetration experiment,the higher the initial concentration of chlorine disinfection by-products and the larger the inflow,the faster the activated carbon penetrates,and the larger the adsorption capacity and the higher the utilization ratio of activated carbon were.When the initial concentration of chlorine disinfection by-products increased from 0.5 times to 2 times the national standard limit at c/c0=0.5,the capacity utilization ratio of activated carbon increased by 15.12%,9.27%and 9.98%,respectively.With the increase of influent flow rate from 52 mL/min to 158 mL/min,the capacity utilization of activated carbon rised by 3.86%,5.41%and 1.22%respectively at c/c0=0.5.The higher the height of activated carbon bed,the longer the penetration time of activated carbon was.However,the height of activated carbon bed had little effect on the utilization rate of activated carbon adsorption capacity.5.A 10-inch filter core activated carbon water purification device with 100 L/h water treatment capacity was designed.The main design parameters of the device were as follows:the initial concentration of CHCl3 was 120?g/L,and the effluent concentration was required to be less than 10?g/L.The experimental results were as follows:The utilization ratio of activated carbon bed was 80.00%.The first-class activated carbon adsorption unit needed to replace the filter element every two months,with an annual expenditure of 222 yuan.The secondary activated carbon adsorption unit needed to replace the filter element every four months,with an annual expenditure of 198 yuan.the tertiary activated carbon adsorption unit needed to replace the filter element every six months,with an annual expenditure of 189 yuan.This study provided data support for the application of activated carbon in controlling chlorine disinfection by-products in drinking water.At the same time,by exploring the adsorption mechanism of activated carbon for chlorine disinfection by-products,it provided theoretical basis for improving the adsorption efficiency of activated carbon.