Integration Of Control Technology For Chloral Hydrate In Drinking Water

Chlorine disinfectant is the most commonly used disinfectant in drinking water treatment,which fully guarantees the microbiological safety of drinking water,but it can also react with natural organic matter?NOM?in water to produce a variety of chlorination disinfection by-products?DBPs?.Among them,the CH content is second only to trihalomethanes?THMs?and haloacetic acids?HAAs?,and has a higher risk of exceeding the standard.At present,the removal of CH precursors was basically a single process and a simple process combination,but lacked the process integration technology to remove the CH precursors.Based on the previous research of the research group,this paper took raw water,humic acid raw water and bovine serum albumin raw water in a certain area in the south as the research object,and used pretreatment and intensified conventional process to integrate the removal of CH precursors in different target water samples.Provide technical guidance for the removal of CH precursors in the water treatment process of the waterworks to ensure the safety of drinking water quality.The pretreatment studies showed that the three kinds of PAC?wood,coal and coconut shell?had good adsorption effect on CH and the adsorption performance was equivalent.They were all suitable for the emergency treatment of water quality CH exceeding the standard;when the three kinds of PAC were added 50 mg/L,50 mg/L and 30 mg/L respectively,the best removal of CHFP,but coconut shell was better than wood and coal.The three kinds of PAC mainly controled CHFP by adsorbing aromatic protein organic matter and microbial metabolite organic matter.PAC can enhance the control effect of coagulation and sedimentation on CH precursors.Compared with coagulation alone,the removal rate of CHFP by adding 30 mg/L coconut shell PAC increased by 23.67%.The adsorption of powdered carbon and pre-oxidation had synergistic effect.Compared with the adsorption of 30 mg/L coconut shell PAC alone,the optimal dosage of the composite pre-oxidant KMnO₄+ClO₂ was0.8 mg/L+0.2 mg/L.The removal rate of the body was increased by 12.68%.PAC adsorption/pre-oxidation/coagulation had a prominent effect on the control of CH precursors in raw water.When the dosage of composite pre-oxidant KMnO₄+ClO₂ was 0.2 mg/L+0.8 mg/L,the removal of CHFP in raw water was carried out,the rate reached 73.11%.Intensified conventional process research showed that:enhanced coagulation sedimentation was a more effective method to remove CH precursors from water.When the dosage of PACl was 4.0 mg/L,the removal rates of raw water,humic acid and protein raw water were respectively 59.55%,63.69% and 60.02%;another 0.05 mg/L PAM coagulant was added,and the removal rates reached 3.26%?5.62% and 0.35%,respectively.Although the secondary microflocculation enhanced filtration had limited capacity for CH precursors,the optimal dosage of poly aluminium chloride?PACl?for secondary microflocculation enhanced filtration were 0.1 mg/L,0.3 mg/L and 0.1 mg/w compared to direct filtration.L,the removal rate of CH precursors in raw water,humic acid raw water and protein raw water increased by9.60%,12.30%and 5.28%,respectively.The removal rates of raw water,humic acid raw water and protein raw water by the enhanced coagulation sedimentation combined with enhanced precipitation integrated process were 68.02%,70.95% and 69.53%,respectively,and the conventional process of filtering the amount of PACl was 2.0 mg/L.Increased by16.00%,15.65%and 19.90%.The pretreatment and strengthening conventional process research showed that:the pre-adsorption/intensification conventional integration process was ideal for the removal of raw water,humic acid raw water and protein raw water.The removal rates of CH precursors in coagulation sedimentation effluent were 62.87%,65.19% and 68.88%,respectively.And the removal rates in filtered effluent were 76.87%,81.70% and 75.72%,respectively.Pre-oxidation maximized regular integration when the pre-oxidant KMnO₄+ClO₂ were applied at 0.5 mg/L+0.5 mg/L,0.2 mg/L+0.8 mg/L,and 0.5 mg/L+0.5 mg/L.The removal efficiency of CH precursors in raw water,humic acid raw water and protein raw water were obtained,and the removal rates were 78.32%,81.20% and 83.85%,respectively.PAC adsorption/pre-oxidation/intensification conventional integration process had strong applicability to the removal of CH precursors in different water quality.The removal rate of CH precursors in raw water,humic acid raw water and protein raw water were respectively determined by the integrated process.It reached 82.76%,86.23%and 81.65%,and were21.51%,27.07% and 27.76% higher than the conventional process?0.5 mg/L of NaClO and2.0 mg/L of PACl?.The PAC adsorption,pre-oxidation and strengthening of conventional processes of powder carbon complement each other to form a multi-stage CH water quality protection barrier,which was suitable for water sources with CH risk exceeding the standard.