The Effect Of Pre-oxidation On Coagulation Efficiency In The Pilot-scale Treatment Of Source Water

With the rapid development of industry in our country, water pollution is more and more serious, the safety problem of water quality has attracted a widely attention, the research of water purification process has a realistic meaning. A pilot-scale purification apparatus was used to investigate the effect of pre-oxidation on coagulation efficiency for the source water treatment. The source water was from a reservoir in the north of China. Three oxidants were used in this study, including: potassium permanganate, sodium hypochlorite and ozone. Pollutants in the resource water were oxidized via adding the oxidant prior to coagulation process. Samples were collected from the effluent of every react unit to analyze some indexes, include turbidity, residual Al, UV254 and three-dimensional fluorescence. Compare the indexes of blank group and experimental group to study the effect of pre-oxidation on coagulation efficiency.The results show that:(1)The pre-oxidation could reduce the effluent turbidity. Using potassium perma nganate, sodium hypochlorite and ozone as the oxidants, the average removal efficien cy of turbidity increased by 10.99%, 10.89% and 11.21%, respectively;(2) The pre-oxidation can also reduce the residual Al of the effluent, Using potassium permanganate, sodium hypochlorite and ozone as the oxidant, the total Al is 0.162 mg/L, 0.167 mg/L, 0.155 mg/L and decreased by 54.62%, 53.22%, 56.58%, respectively; the soluble Al is 0.150 mg/L, 0.161 mg/L, 0.139 mg/L and decreased by 55.75%, 52.50% and 59.00%, respectively;(3) Using potassium permanganate, sodium hypochlorite and ozone as the oxidant, the UV254 value decreased by 36.71%, 21.78% and 47.78%;(4) The result of the three-dimensional fluorescence proved that the raw water has three DOM, these are tryptophan-like, microorganism metabolites and fulvic acid-like. Using potassium permanganate, sodium hypochlorite and ozone as the oxidant, the efficiency of tryptophan-like increased by 26.64%, 21.71% and 32.76%, respectively; the efficiency of microorganism metabolites increased by 33.94%, 27.25% and 39.63%, respectively; the efficiency of fulvic acid-like improved 36.26%, 33.32% and 41.98%, respectively.It was concluded that traditional coagulation can reduce turbidity and residual Al of the effluent, but it do not have obvious effect to remove organic matter. When the pre-oxidation is used, the removal efficiency of turbidity and residual Al will keep improving, and it can remove organic matters obviously, especially for the DOM. Therefore, the pre-oxidation treatment has an important role on improvement of water quality and has a good prospect.