The Study On The Water Filtration Process Optimization And Treatment Of Reservoir Water

This study is part of the sub-project of "the Twelfth Five-Year Guideline" on major projects of science and technology for water pollution control and management:"Water Supply System Operation Characteristics and Process Design Technology Research" (National Major Water Project (2012ZX07408001). The research is based on the analysis of the current situation of the development of water treatment filteration process, combined with the actual water research, summing up the current problem of feed water treatment plants filter section in our country, setting up the corresponding experiment scheme according to the problem, and through the combination of pilot test and field test, conducted a series of experimental research, which provides theoretical basis and technical support for the actual water filteration.The research mainly includes three aspects:(1) the new filteration aid optimization experiment research; (2) filter building parameters optimization experiment research; (3) high-algae water quality filter optimization experiment research.Through the optimization study of the new type of filter aid, if choosing sodium hypochlorite as a new type of filter aid, according to the results from the experimental research, sodium hypochlorite was effective on the reduction of turbidity and suspending particles, on enhancing the filtration capability of the filter, and on improving the water quality. The addition of 2 mg/L sodium hypochlorite reduced the filter effluent turbidity and particle counts by 60% to 76% and extended the filtration cycle by 8 hours; results also indicated that the enhanced filtration predominantly removed the particles with diameter around 2-5μm, and can effectively reduce the penetration of particles caused by the filtration rate mutation; particle counter can measure the concentration of particles in effluent accuracy.In the experimental study on the optimization for construction of filter parameters, through the contrast test of different filtering materials, the results showed that coal-sand dual media filter has the advantage of strong carrying capacity and slow head loss increase. The experiment compared the domestic and foreign setting parameters of coal-sand dual media filter, set up the test filter column of different filter configuration, and conducted comparative tests. The results showed that coal-sand dual media filter under domestic conventional parameters have an obvious problem of turbidity and particulate penetration. Reducing the filter speed and increasing the thickness of the quartz sand filter layer can delay the penetration time of particles and turbidity, yet cannot solve the problem of turbidity and particle through filter layer; filtering before adding the sodium hypochlorite can effectively reduce the filter water turbidity and the number of particles, but cannot delay the time of turbidity and particles through the filter; since the underlying quartz sand thickness is the key factor which results in turbidity and particle through filter layer,it would be effective to reduce sand layer effective particle size to 0.5 mm. Coal-sand dual media filter in quartz sand layer thickness of 300 mm, the effective diameter of 0.5 mm, smokeless coal seam thickness of 600 mm, the effective diameter of 1.0 mm configuration has the best filtering performance.In optimization experiment for high-algae water filter, field test found that, high algae water quality can significantly shorten the filter filtration cycle, worsen the effluent water quality, cause serious filter layer jams, and result in backwash difficulties and other issues. Filter column test showed that sand filter can be affected by high-algae water quality, filtration cycle shortened to about 10 h. Coal-sand dual media filter filtration cycle can reach about 20 h, which has obvious advantages; as the algae enters into the sand filter, it is mainly trapped in the surface layer of filter material, and it grows rapidly with the filtration cycle.10 cm under the filter layer is the part that contains least amount of algae.Increasing 10 cm anthracite on sand filter layer can effectively prolong the filter cycle under the condition of high algae water quality and improve water quality; the addition of 4 mg/L sodium hypochlorite reduced filter particle counts by 78%, and more than doubled the filtration cycle; at the same time, however, adding the sodium hypochlorite will lead to the rise in the turbidity of water after filtration.