Engineering Test Study On Sand Filter Reconstruction In Waterworks

Sudden water environmental pollution incidents occur from time to time throughout the country,and the safety risks of water sources cannot be ignored.Especially when incidents such as ship overturns,upstream sewage discharges,and heavy rains occur,how to ensure drinking water safety is a major challenge facing the water industry.Sand filter is the last process before disinfection of the water plant,which is critical to the safety of water supply.Without the addition of a special deep processing unit,transforming a sand filter into a carbon sand filter is an economical and economical process.Applicable measures.According to this technical path,pilot test and engineering application exploration were carried out.Add 700mm,700mm,800mm three kinds of activated carbon layers with different thickness on the 700mm raw sand filter layer,select columnar coal granular activated carbon with a diameter of 1.5mm,8-20 mesh raw coal crushed activated carbon,8-30 mesh raw coal crushed activated carbon,choose 13 L/（m²·s）,15 L/（m²·s）,17 L/（m²·s）three different backwashing strengths,and the optimum filtration speed was determined by orthogonal test under the condition of 8m/h Working conditions:700mm thick 8-20 mesh raw coal crushed granular activated carbon,backwashing strength of 15L/（m²·s）,compared with sand filter columns,the removal efficiency of carbon sand filter columns for turbidity is different.Not large（removal rate is greater than 95%）,the average removal rates of oxygen consumption,UV₂₅₄,ammonia nitrogen,and nitrate nitrogen increased by about 10.4%,52.9%,2.7%,5.7%,respectively.Carry out engineering application research of sand filter conversion to carbon sand filter.Test modification in a ten-sand sand filter with a processing capacity of 180,000 tons/day,including adding air washing system,replacing 400mm supporting layer,700mm Filtering sand,filling with activated carbon,and long-term running results under the best working conditions obtained from the pilot test show that the average removal rates of the sand filter for turbidity,oxygen consumption,UV₂₅₄,ammonia nitrogen,and nitrate nitrogen were95.87%,36.92%,23.17%,48.57%,3.92%;and carbon sand filter has better removal effect,the average removal rate is 95.52%,52.31%,64.97%,57.14%,5.88%,hygienic indicators of effluent（The total number of colonies,total coliforms）and disinfection by-product indicators（trihalomethane）are far lower than the limit values of GB5749-2006 Sanitary Standard for Drinking Water,and there is no safety risk in effluent.Orthogonal experimental verification of engineering application with the same three factors and three levels as the pilot test,the optimal operating conditions obtained are consistent with the results of the pilot test.The research results provide technical support and engineering demonstrations for the water plant to prevent accident risks,enhance water supply safety guarantee capabilities,and optimize the sand filter.