Experimental Study On The Treatment Of Snowmelt Water In Alpine Pastoral Area By Electrobiological Coupled Slow Filtration Technology

Snowmelt water as a source of drinking water is generally relied on in the alpine pasturing areas.However,due to the natural environment,climate change,animal husbandry industry and human activities,the snowmelt water quality in the alpine pasturing areas is typical of intermittent and occasional micropollution,especially in the spring and summer when the temperature rises and the precipitation is more serious.Major pollutants include ammonia nitrogen,dissolved organic matter（DOM）,microorganisms,and excess iron and manganese metal ions in groundwater in some areas.As the main source of water for herdsmen in alpine pastoral areas,if the water pollutants are not dealt with effectively in time,it will bring serious health risks to the human body.In this paper,the 1#electro-biological coupled slow filter column（2.5V）reactor was constructed to treat snowmelt water in simulated alpine pastoral areas,to explore its removal effect on turbidity,p H,ammonia nitrogen,dissolved organic matter（DOM）and iron and manganese in the water,and compared with the control group（2#traditional slow filter column）,to explore its advantages in degradation of main pollutants.The synergies between applied voltage and microorganisms in the process of pollutant degradation were analyzed.Finally,the influence of applied voltage on microbial community diversity on the surface of filter material in the reactor was explored by high-throughput sequencing technology,in order to explore the mechanism of pollutant degradation from the perspective of microorganisms.The research results showed that:（1）In order to explore the purification effect of electro-biological coupled slow filtration technology on snowmelt water in simulated alpine pastoral areas,a comparative study was conducted on 1#electro-biological coupled slow filtration column（2.5V）and 2#traditional slow filtration column（0V）.The water temperature is 4-17℃,the filtration rate is 0.2m/h,and the inoculation method is adopted.The experiment shows that the successful time of 2#filter column biofilm hanging is 24d;During stable operation,the average removal rates of turbidity,p H,NH₄⁺-N,COD_Mn,UV₂₅₄,Fe and Mn were 96.08%,5.45%,66.50%,44.80%,37.61%,91.72%and 96.25%,respectively.The success time of 1#filter column biofilm hanging was 18d.During stable operation,the average removal rates of turbidity,p H,NH₄⁺-N,COD_Mn,UV₂₅₄,Fe and Mn were 96.87%,9.54%,71.76%,63.38%,57.52%,90.05%and96.73%,respectively.The effluent water quality conforms to the national Sanitary Standards for Drinking Water（GB5749-2022）.Compared with the 2#filter column,the successful hanging time of the 1#filter column is reduced by 6d,and it has a better treatment effect on pollutants.The average removal rates of p H,NH₄⁺-N,COD_Mnand UV₂₅₄are increased by4.09%,5.26%,18.58%and 19.91%,respectively.（2）The 2#traditional biological slow filter column was used to simulate dissolved organic matter（DOM）in snowmelt water in alpine pastoral area,which mainly played the role of microbial degradation of activated carbon filter layer.The 1#electro-biological coupled slow filter column not only enhanced the microbial degradation of activated carbon filter layer,but also played the role of electrocatalytic oxidation of quartz sand layer,and the manganese sand layer further removed organic pollutants through biological action.Moreover,three-dimensional fluorescence spectrum analysis showed that in electrobiological coupling slow filtration technology,quartz sand filter material layer could convert refractory organic matter into tryptophan material with good biodegradability through electrocatalytic oxidation,and finally further removed by microbial action in manganese sand layer,thus achieving efficient DOM degradation.（3）High throughput sequencing was used to analyze the colony structure of the biofilm near the anode and cathode of 0 V and 2.5V,and it was found that the external voltage stimulation had a certain effect on the community structure of bacteria and fungi,and there were more strains that could use difficult biodegradable substances at the phylum level and genus level.At the level of bacterial community structure,compared with BH,the relative abundance of Proteobacteria in DHA2.5 and DHC2.5 increased by 6.3%and 3.7%,respectively.The proportion of Kiritimatiellaeota in DHA2.5 and DHC2.5 increased by 3.14%and 2.35%,respectively.On a generic level,The phase of Malikia,Geobacter,Aquabacterium,Macellioides,Bacteroides and Desulfomicrobium in an electric bioreactor Their abundance increased to varying degrees,and new dominant bacteria are emerging in Sulfur,Hydrogenophaga,Desulfuromonas,and Comamonas.At the fungal community structure phylum level,compared to BH,In DHA2.5,the relative abundance of Ciliophora,Mucoromycota and Ascomycota were improved to varying degrees,and a new Arthropoda was found in DHC2.5.At the genus level,the relative abundance of Paramecium and Mucor in the electric bioreactor was improved,especially Paramecium was abundant near the cathode and anode.At the same time,new bacteria genera of Cystobasidium,Thelebolus,Solicoccozyma and Scolecobasidium were produced.