The Removal Characteristic Of DBPsFP By Potassium Permanganate Preoxidation During Chloramination Of Cyclops

During chlorination process, the Cyclops metabolite would produce disinfection by-products. The objective of present study is to investigate the disinfection by-products precursors removal characteristics by potassium permanganate preoxidation under different conditions. The research indicates that:along with the increasing dosage of potassium permanganate (KMnO4), the concentration of 1,1,1-trichloropropanone (1,1,1-TCP),chloral hydrate (CH),chloroform (TCM) content increases, while the concentration of dichloroacetic acid (DCAA) decreases, this index for chloropicrin (TCNM) increases in the first place while decreases after it reaches its peak. In our experiment, when the KMnO4 dosage exceeds 3mg/L, CH, TCNM, DCAN, TCAN, DCAA, TCAA and 1,1-DCP would reach their best removal efficiency, which could exceed 72.2%.The optimum preoxidation time is 20 minutes. With the prolonged preoxidation time, the concentration of DCAN, DCAA and TCAA decreases, while the same item of TCM and CH changes in the opposite way. The concentration of TCNM, TCAN and 1,1,1-TCP firstly increases and then decreases. On the contrary, the concentration of 1,1-DCP decreases at first and then increases continuously. pH also has a significant impact on removal efficiency. When pH is lower than 7, TCM generation would be restrained. And when pH is higher than 7, the concentration of CH, DCAA, DCAN, TCAN, TCNM and 1,1,1-TCP decreases along with the increase of pH. The removal efficiency would reach its highest value of 80% when the pH is 9. With the increase of temperature, the concentration of DCAA, TCAA and TCM increases, while 1,1-DCP, DCAN and 1,1,1-TCP decreases correspondingly. Furthermore, CH firstly increases and then decreases. TCAN shows the opposite trend to CH. By analyzing the removal characteristics of most DBPsFP indicate that the optimum temperature is 30℃.With the continuous increase of coagulant, the concentration of TCP, TCAA, TCAN firstly increases and then decreases and DCP, DCAA, DCAN continuously decreases. TCNM firstly decreases and then increases. When the amount of coagulant is 30mg/L, the disinfection by-products reaches the lowest value. Preoxidation strengthening coagulation way of coordination compound action of strong adaptability, under the condition of different pH value has a better removal effect. When the water temperature below 20 degrees Celsius pre oxidant have played an important role to help setting, but higher than the temperature conditions of 20 degrees Celsius help condensation is not obvious.