Experimental Study On Removal Of Manganese And Ammonia Nitrogen From Drinking Water By Zeolite Biological Aerated Filter

Among surface water sources,pollution caused by manganese and ammonia nitrogen has become an urgent drinking water safety problem.Aiming at the defect that the conventional water treatment process cannot effectively remove manganese and ammonia nitrogen,a zeolite filter biological filter is designed in this paper.By pilot tests,the filtration direction,filtration rate,water temperature and coexisting organic matter on the removal of manganese and ammonia nitrogen are studied in this paper.The results show that:The inoculation membrane can save membrane time compared with natural membrane formation.The zeolite biofilter forms a stable clinker,and the membrane formation culture period is about 60 days.The difference of maturation time of the biofiltration membrane between the upward flow filter and the downward flow filter is not obvious.The high-efficiency removal of manganese in the downflow filter is in the second half of the filter material,the high-efficiency removal of ammonia nitrogen is in the first half,and the ammonia nitrogen only has a slight impact on the manganese removal effect in the first half;the ammonia nitrogen in the upward flow filter is in the first half.The section has reached the water effluent standard,and the manganese removal section continues to the entire filter tank.It can be concluded that the manganese removal effect is more obviously affected by the ammonia nitrogen concentration.The change curve of dissolved oxygen in the filter is similar to that of NH4+-N.Under the condition of sufficient 0-20cm DO content,the filter material can remove NH4+-N and manganese quickly at the same time.As the concentration of ammonia nitrogen in the raw water gradually increases,the manganese removal effect of the downward flow will be better than that of the upward flow.When the running filtration rate in the zeolite filter is gradually increased from 2m/h to 6m/h,the water output effect of the filter will be affected to varying degrees.When the concentration of influent humic acid increases,the effectiveness of biological filter for removing ammonia and nitrogen will become worse;the efficiency of biological filter for removing manganese will decline rapidly,but will gradually stabilize in the next few days until the effluent manganese concentration reaches the national standard Limit.Through comparative experiments under different water temperatures,it can be seen that the down-flow zeolite biological filter can treat influent Mn2+≤2.0mg/L,NH₄⁺-N≤3.0mg/L or influent Mn²⁺at a water temperature of 26℃and a filtration rate of 6m/h.The treated effluent can meet China’s"Sanitary Standards for Drinking Water"（GB5749-2006）for composite polluted water sources≤1.0mg/L and NH₄⁺-N≤4.0mg/L.When the water temperature is about 9℃,the manganese concentration in the effluent changes greatly.This is because the nitrite bacteria can carry out the normal metabolic activities for the bacteria in winter,but the temperature is too low in the winter to inhibit the activity of the nitrate bacteria.Therefore,the biological filter is prone to have a large amount of nitrite nitrogen in winter.When the concentration of influent pollutants is high or the filtration rate exceeds the limit value,the upward flow zeolite filter and the downward flow zeolite filter can be connected in series to obtain a secondary biological filtration process.The cascade process can treat 3.0-4.0mg/L manganese in the influent water and4.0mg/L ammonia nitrogen in the influent water.The secondary biological filtration process can remove the higher operating speed with a filtration rate of up to 10m/h.At this time,the effluent quality is still good.