Discussion On Comprehensive Treatment Of Micro-polluted Water Source With Biological Oxidation And Manganese Removal As The Core

Over the years,the frequent occurrence of seasonal manganese pollution has made many waterworks unable to face.This has led some water operators to pay more and more attention to drinking water and manganese removal technology.Throughout the history of drinking water purification in China,it has been found that drinking water and manganese removal technology has been developed in the groundwater field before,and there is little research on the problem of seasonal manganese exceeding the standard in complex surface water.In this paper,we will explore and further study the biological manganese removal by using the manganese removal microorganisms that may exist in the high-density sedimentation tank return sludge in the water treatment plant.Then,the bio-filler combined with biological activated carbon is used to form the biochar-biofilm process,and the possibility of biological manganese removal capacity and other comprehensive water purification capacity is discussed.The specific research is as follows:1)Through the research and analysis of the sludge discharge water and the filter backwash water in the high-density sedimentation tank of the water plant,it can be known that the primary sludge in the sludge pond of the water plant may have a certain degree of biological manganese removal capacity.When the intensified aeration reaction of the primary sludge is carried out for a period of time,the microorganisms in the sludge actually exhibit an efficient manganese removal ability.A series of experiments were then initiated to investigate the trend of manganese removal capacity of the reactor with built-in sludge under different conditions.In the beaker with a sludge concentration of 1250mg/L,5mg/L Mn²⁺was added,and the removal rate of Mn²⁺after intensive aeration for 20min was 72.8%.Then the reaction rate slowed down,and after 120min,the Mn²⁺concentration was the most stable at 0.5mg/L or so.Microbial enhanced aerated manganese removal reaction conforms to the second-order kinetic model.The higher the concentration of Mn²⁺in the reactor,the faster the reaction rate and the higher the Mn²⁺removal rate.Fe²⁺concentration promoted the microbial manganese removal reaction,and the optimal concentration was 2mg/L.On the other hand,the presence of Fe²⁺had an important effect on the sustainability of the reaction.Temperature can promote the microbial manganese removal reactor,but the effect is not great.When the pH value in the reactor is lower than 3.5,Mn²⁺precipitates,which causes the Mn²⁺concentration of the effluent to rise.When the pH environment is neutral and alkaline,the reactor works well.At the beginning of the organic explosion,the microorganisms will cause some interference with manganese removal,but after a period of time,the microorganisms will be restored to the original state.Finally,when the temperature is 30°C,the pH is slightly alkaline and sufficient Fe²⁺is added,the microbial manganese removal reactor is in the best operating state,the Mn²⁺removal rate is over 97%,and the effluent Mn²⁺concentration is 0.05 mg/L.In line with national drinking water effluent standards.At this time,only the ammonia nitrogen in the other water-out indicators was significantly reduced,and the turbidity even increased.2)Biochar-biofilm combined reaction system was constructed with microbial and manganese removal as the core.The application of the new reactor built under this system in the micro-polluted water source integrated water purification system was studied.The main effects of Mn²⁺,COD_Mn,UV₂₅₄,ammonia nitrogen,total nitrogen,turbidity removal and factors affecting the removal efficiency were investigated.The reaction system ensures high manganese influent while adding a small amount of polyaluminium ferric chloride and activated carbon.The upper part of the reactor is an aerobic zone consisting of a biofiller and an aeration unit.The lower half forms an anoxic portion from the accumulated activated carbon,and the reactor is activated for about one month to form a stable biochar-biofilm process.The results show:In the biochar-biofilm reaction system,when the flow rate is 3 L/h and the influent Mn²⁺concentration is 5 mg/L,the effluent concentration of Mn²⁺is about 0.01 mg/L,and the removal rate is greater than 99%;With the increase of reactor flow rate,the removal effect of Mn²⁺showed a downward trend.When the flow rate was 9L/h,the effluent Mn²⁺concentration was close to 0.1mg/L.The removal rates of COD_Mn,UV₂₅₄,ammonia nitrogen and total nitrogen are inversely proportional to the flow rate.When the flow rate is less than or equal to 5L/h,the removal rates are 36%,52%,94%and44%,respectively.When the flow rate is 9 L/h,the removal rate drops to 20%,44%,85%,and 35%.There is not much relationship between turbidity and flow.The removal rate of ammonia nitrogen and total nitrogen from the effluent of the reactor is proportional to the temperature.The most suitable temperature is 35°C.When the flow rate is 6L/h,the removal rates of ammonia nitrogen and total nitrogen are 99%and60%,respectively,and the removal rate decreases with the increase of flow rate.The thickness of the bottom biochar layer in the reaction system will increase with the running time of the reaction system,but there will be an upper limit,and the activated carbon and the lost activated carbon will reach a balance.When the thickness of the biochar layer increased from 4cm to 8cm,the removal rate of COD_Mn increased by 10%on average in the reaction system,and the removal rate of UV₂₅₄ also increased,with a maximum of nearly 15%.3)Microscopic observation of the biofiller in the SBR reactor after two months of continuous operation.Biochar-biofilm combined with biochar on the bottom of the reactor for basic analysis of microbial diversity.It is initially proved that the reaction result is caused by microbial activity.