Application of Enhanced Coagulation Technology in Water Supply Treatment Engineering

Enhanced coagulation technology is currently mainly used in the water supply sector to control the content of disinfection byproducts in drinking water in order to achieve higher drinking water quality requirements.

(1) There has been considerable research and numerous successful engineering examples of enhanced coagulation treatment for slightly polluted water sources (primarily reflected in excessive levels of ammonia nitrogen and organic matter (COD, TOC, BOD), etc.). Laboratory and simulated production tests have demonstrated that enhanced coagulation effectively removes NOM from raw water and significantly improves the effluent quality of slightly polluted water. Furthermore, enhanced coagulation technology is increasingly being applied in other areas. It has been reported that enhanced coagulation is more effective than conventional coagulation in removing algae. The use of potassium permanganate composite agent PPC can effectively improve the algae removal rate in water. Compared with potassium permanganate and chlorine, the algae removal rate after precipitation is 14% higher than that after prechlorination, and the algae removal rate after filtration is 3.9% higher at the same dosage of PPC. Studies by Packham and Black et al. have shown that EC can also effectively treat high-color water; various novel composite... The development of combined agents (such as PASS flocculants, polymeric CGA flocculants, etc.) has further advanced the application of enhanced coagulation: for example, the combination process of potassium permanganate composite agent [CP:NaoCl=3:1.2 or 3.5:1.7] and powdered activated carbon has a significant effect on degrading organic matter and improving the ability to remove turbidity, odor, and color, and has a good effect on enhancing coagulation and reducing the amount of prechlorination; the use of magnetic ion exchange resin to enhance coagulation (magnetic ion exchange resin (MIEX)) is very effective in removing THM and HAA precursors even under low TOC concentration, low UV and high alkalinity conditions, with a removal rate of more than 60%, or even 90%. Ferric salts can be used as both pre-oxidants and coagulants, and have a dual role, while other oxidants do not have this dual function. Therefore, ferric salts (such as K2FeO)

(2) Through long-term research, it has been concluded that the key to treating low-temperature, low-turbidity water lies in selecting appropriate coagulants and coagulant aids to enhance the flocculation process. In recent years, there have been numerous reports of successful engineering applications of enhanced coagulation methods in low-temperature, low-turbidity water treatment. To improve drinking water quality, in addition to selecting good water sources and strengthening their protection, the first consideration should be enhancing or optimizing conventional water treatment processes to ensure that their technical equipment and parameters are at their best. Given my country's current economic strength, it is unrealistic to demand a widespread increase in advanced treatment; therefore, more efforts should be made to improve conventional treatment methods. Enhanced coagulation, developed on the basis of conventional coagulation treatment, is a process for removing organic matter, especially humic acid-rich organic matter, from water. Compared to other treatment processes, it has lower costs and can be implemented with minor modifications to existing treatment equipment. Domestic and international experimental studies have shown that controlling the pH value of coagulation treatment at around 5-6 and appropriately increasing the dosage of coagulant can effectively remove organic matter from water. Most source water exhibits good removal efficiency for organic matter. Enhanced coagulation increases the costs associated with corrosion prevention and pH adjustment in water treatment systems. However, for source water with low organic matter content, it can eliminate the investment and operating costs of GA adsorption equipment. Conversely, for source water with high organic matter content, enhanced coagulation can further improve the operating efficiency of GA adsorption equipment. Ultimately, the goal is to achieve a significant improvement in water quality at a lower cost and by fully utilizing existing processes. Therefore, enhanced coagulation experiments on source water are necessary to determine the optimal pH range and coagulant dosage for organic matter removal. Further research is needed on the combined use of enhanced coagulation with other processes (such as GA adsorption), as well as the development of novel, highly efficient coagulants and coagulant aids. This is of great practical significance given the widespread micro-pollution of source water in my country, and it is believed that enhanced coagulation technology has significant application and promotion value in water treatment engineering.

(3) Maximum removal of impurities and turbidity; maximum removal of TOC and DBP precursors; minimum residual coagulant (i.e., the coagulant should be fully utilized at the minimum dosage); minimum sludge production; minimum operating costs; and minimum environmental impact. These are comprehensive indicators for enhancing coagulation effectiveness and represent the goals of water treatment engineers. The development of various reactors, the control of optimal hydraulic conditions, and the matching of various combined processes are all aimed at achieving this objective.

(4) Especially effective and requires less dosage when organic matter concentration is high.