Study On Removal Of Chloral Hydrate In Drinking Water By Carbon-based Adsorbent

Among the by-products of chlorine disinfection,Chloral Hydrate?abbreviated as CH?is second only to trihalomethane and haloacetic acid in terms of generation and harm,and there are still few relevant studies on CH at home and abroad,and there is relatively little experience in treatment.Based on this background,for the purpose of studying the effect of carbon-based adsorbent on CH removal and preliminary design of household water purifiers,the CH content of drinking water in 36 typical cities in China was first investigated,and then the safety performance,structural characteristic and adsorption performance were comprehensively considered,from 9 types among the carbon-based adsorbents?including activated carbon,activated carbon fiber and graphene?,the better categories were selected.The static and dynamic adsorption experiments were used to explore the effect of the carbon-based adsorbent on CH removal.The device was designed and tested according to the experimental results.The main findings are as follows:?1?The detection rate of CH in 36 water samples of water quality investigation is 88.89%,and the CH content of 3 water samples exceeds 10?g/L as prescribed by the national standard.Calculating the variance and outlier ratio shows that the representativeness of the mode is weak,and the CH content in drinking water varies greatly among cities.In addition,the overall distribution of CH is slightly higher in the south than in the north,and slightly higher in the east than in the west.?2?The screening results of carbon-based adsorbents show that,in terms of overall safety performance,structural characteristic and adsorption performance,among 9 carbon-based adsorbents,type C-2 coconut shell granular activated carbon and type CF-2 activated carbon fiber have better performance and are more suitable for the treatment of domestic drinking water.?3?A household water purifier was designed based on the data of adsorption experiment.Set CH influent concentration c₀to 20?g/L,water purifier water flow rate Q to 200L/h,effluent concentration c_eto?2?g/L,select CF-2 type activated carbon fiber as adsorbent,packed density is 103.94kg/m³.A standard 10-inch filter element?diameter to height ratio of 0.28?is used,and the carbon bed utilization rate is 67.6%.As for the primary,secondary,and tertiary water purification devices:at 4.55h,11.28h,and 18.01h during the working time,the removal rate of CH can reach more than 90%,and the total amount of purified water is 0.91m³,2.256m³,3.602m³;pressure losses are 0.0168MPa,0.0336MPa,0.0504MPa;replace period of the filter element is 3,7,12 months;the annual expenditure of adsorbent is 178 yuan,143 yuan,133 yuan.?4?Using CF-2 type activated carbon fiber as adsorbent,a customized household water purifier is used for continuous operation to carry out the detection experiment.Under the conditions of inlet water pressure 0.2MPa and purified water flow rate150L/h,the operation time of the water purifier is within 13 hours,the removal rate of CH is more than 90%,and the total purified water volume is about 1.95m³,which can supply a family of four for about half a year.?5?Combining the calculation results,experimental results and the standards implemented at home and abroad,it is recommended to add a high quality limit of2?g/L to the 10?g/L standard limit to take into account regional differences and encourage qualified areas to provide better quality for residents drinking water.