Biofiltration Treatment For Composite Pollution Of Manganese And Ammonia Nitrogen In Raw Water

Manganese and ammonia nitrogen have become the typical pollutants in drinking water source.The combined pollution of manganese and ammonia nitrogen often occurs in drinking water source,but the conventional treatment process can not be effectively removed.In order to solve this problem,this paper studies the treatment effect of biofilter on the combined pollution of manganese and ammonia nitrogen by using artificial water samples to simulate the combined pollution of manganese and ammonia nitrogen under the pilot scale conditions,and comprehensively investigates the influence of filter material type,filtering direction,position of aeration port,filtering speed,water temperature and other factors.In this study,a pilot scale biofilter was designed and manufactured.The effects of quartz sand and natural manganese sand,downflow and upflow,bottom aeration and middle aeration on the treatment effect of biofilter were analyzed by parallel experiments.The results show that:The culture cycle of manganese sand filter layer and quartz sand filter layer is not much different,about 60 days.In the treatment of raw water polluted by manganese and ammonia nitrogen,quartz sand filter material is preferred to oxidize ammonia nitrogen,while manganese sand filter material layer can oxidize manganese and ammonia nitrogen at the same time,and there is no significant difference in the removal effect of ammonia nitrogen between the two filter materials,but manganese sand is superior to quartz sand in the removal of manganese.The removal of ammonia nitrogen is mainly concentrated in the first half of the filter layer,and the removal of manganese can take place in the whole filter layer.The filtration direction has no significant effect on the ammonia removal effect,but downflow filtration is beneficial to the removal of manganese.When the concentration of ammonia nitrogen is higher,the bottom aeration is beneficial to the lower filter material to continue to oxidize manganese and ammonia nitrogen.Therefore,for the treatment of the raw water with high ammonia concentration,it is advisable to use a down-flow manganese sand filter with aeration at the bottom.It can be known from the comparison of experiments in different seasons that the down-flow biological filter at normal temperature can treat compound polluted raw water with manganese concentration no more than 3.0mg/L,ammonia nitrogen concentration no more than 2.0mg/L or that with manganese concentration no more than 1.0mg/L,ammonia nitrogen concentration no more than 3.0mg/L.The effluent quality meets the standards for drinking water quality in China,and the filtration rate can reach 6.0m/h at this time.In winter(water temperature is about 10℃),the enzymatic reaction rate in the oxidizing bacteria cells is greatly reduced,the metabolism is slow,and the treatment effect is greatly affected.When the filtration rate is 6.0m/h,the down-flow biological filter can treat compound polluted raw water with manganese concentration no more than 1.0mg/L and ammonia nitrogen concentration no more than 2.0mg/L,and the effluent quality meets the standards for drinking water quality in China.When the combined pollution concentration of manganese and ammonia nitrogen is high,the two-stage biological filtration process of "first-level up-flow manganese sand filter column" + "second-level down-flow manganese sand filter column" can be used.Under the condition of raw water quality with a manganese concentration of3.0mg/L and an ammonia nitrogen concentration of 4.0mg/L,when the filtration rate reaches 12m/h,the effluent quality still meets the standards for drinking water quality in China.The study not only provides a reference for optimizing the operation parameters of biological filtration process,but also provides a design idea for the biological purification process for treating manganese and ammonia nitrogen compound polluted raw water.