| The investigation of the species and concentration of DBPs and their formation potential were conducted with microcystis aeruginosa cell, EPS of microcystis aeruginosa cell, fish oil, DNA, humic acids, starch and bovine serum albumin. There were NDMA precursors in microcystis aeruginosa cell, EPS of microcystis aeruginosa cell, DNA, humic acids and bovine serum albumin, and no NDMA precursors existed in fish oil and starch. With the increase of ozone dose, the variation of THMs which was produced by EPS and starch was insignificant, the concentration of THMs which was produced by DNA increased, the concentration of THMs which was produced by microcystis aeruginosa, fish oil, humic acids and bovine serum albumin decrased, the variation of HAAs which was produced by EPS of microcystis aeruginosa cell, fish oil and bovine serum albumin was insignificant, the concentration of HAAs which was produced by DNA, humic acids and microcystis aeruginosa increased, the concentration of HAAs which was produced by starch decrased. Bromide and iodide increased the reaction activity of biological source material in disinfection process. After bromide and iodide were added, the concentration of TTHMs increased, the variation of HAAs was insignificant.The investigation of the species and concentration of DBPs formation potential were conducted with three micropolluted raw water. No NDMA and its formation potential were detected at raw water and the processes of these three drinking water plants. The THMs formation potential which was produced by the combination of ozonation and chlorination was lower than the formation potential which was produced by single chlorination. The results clearly indicated that the THMs precursors were decreased by ozonation efficiently. The HAAs formation potential which was produced by the combination of ozonation and chlorination was higher than the formation potential which was produced by single chlorination. The results clearly indicated that the HAAs precursors were increased by ozonation. The formation potential of THMs and HAAs was removed by coagulation/sedimentation efficiently. However, soluble microbial products (SMP) and extracellular polymeric substances (EPS), the important precursors of THMs and HAAs, were produced by biological technology in water treatment process.Optimization of coagulation and ozonation processes for removal of organic matters in micropolluted raw water was conducted by a continuous flow pilot scale test. The water source was mainly influenced by agriculture pollution and inland waterway transportation. Coagulation/sedimentation was not enough to treat the micropolluted raw water with highly concentrated organic matter, and the extra ozonation and granular activated carbon (GAC) filtration were necessary. Proper poly-aluminum-chloride-sulfates (PACS), pre-ozone and post-ozone dosages were required for improving the removal performance of organic matters. Considering the treatment performances and economic costs, we found that the optimum PACS, pre-ozone and post-ozone dosages should be8.9mg/L Al2O3,0.5mg/L and2.5mg/L respectively. At the optimum PACS dose, removal efficiencies of93.28%turbidity,27.76%UV254and38.55%COD were achieved at Train B (the control). At the optimum pre-ozone dose, removal efficiencies of95.65%turbidity,54.81%UV254and58.14%COD were achieved at Train A. At the optimum post-ozone dose, removal efficiencies of97.09%turbidity,71.83%UV254and66.11%COD were achieved at Train A.The removal and inactivation of viruses in portable water was conducted in a continuous flow pilot scale system. Bacteriophage MS2was used as model organism for human enteric viruses. The effect of disinfection technologies (single or combination of ozonation and chlorination) and interfering substances (bromide and iodide) on inactivation of viruses, and the removal and inactivation performance of viruses in natural water by the continuous flow pilot scale system were investigated. The results indicated that ozone was more effective in inactivation of viruses than chlorine. The optimum dose of ozone and chlorine was0.5mg/L and1.0mg/L respectively in the combined process of ozonation and chlorination. Bromide and iodide ions in raw water were detrimental to inactivation of viruses by ozone they could consume a certain amount of ozone. However, they enhanced the inactivation of viruses by chlorine, due to the formation of stronger halogenating agent. The continuous flow pilot scale water treatment system was effective in removal of viruses in natural water at optimum conditions, which the dose of ozone and chlorine was0.5mg/L and1.0mg/L respectively.The removal of disinfection by-products (DBPs) and viruses at three drinking water plants (A, B and C) in a city of southern China was investigated. Coliphages MS2and Phixl74were used as indicators of viruses. The results clearly indicated that no NDMA were detected at raw water and the processes of these three drinking water plants. CHCl3exsited in the raw water of Plant A and B widely, however, no THMs was detected in the raw water of Plant C. The titer of MS2and Phix174in the raw water of Plant C was lower than Plant A and B. It can be concluded that the pollution of raw water of Plant C was slight, and the pollution of raw water of Plant A and B was serious. The removal efficiency of MS2and Phix174was over99%by conventional coagulation/sedimentation at Plant A, B and C. MS2and Phix174were not detected in the effluent of these three plants. However, the removal efficiency of UV254and TOC by coagulation/sedimentation was only22.05%and64.57%at Plant A,17.64%and11.89%at Plant B,59.79%and21.32%at Plant C respectively. Acorrding to the previous study in this paper SMP and EPS were the important precursors of THMs and HAAs. It is worthwhile to note that a new peak at2956cm-1had emerged in the infrared spectrogram of biological pretreatment effluent of Plant B. This result is presumably due to the SMP and EPS which are related to bacteria metabolism and cell lysis produced in biological filter. |
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