Study On Deep Denitrification Efficiency Of Denitrification Filter With Reed Straw As Slow-release Carbon Source

Due to the low C/N ratio of secondary effluent of rural domestic sewage,additional carbon source is needed in the process of deep denitrification,which makes the cost of treatment rise and easy to cause secondary pollution.Reed straw is a common agricultural waste.Through the analysis of denitrification effect,using cost and operation mode,the carbon source slow-releasing from the soaking of reed straw using as an additional carbon source in denitrification filter is realized as a resource utilization of reed straw and cost reducing of rural sewage treatment.In this paper,the untreated reed straw was selected as the slow-release carbon source material through static carbon release experiment,three-dimensional fluorescence,molecular weight distribution and other preliminary experiments.Four denitrification filters were constructed in the laboratory with sodium acetate as the control and three stages of the slow-release soaking solution of reed straw with good biodegradability as the additional carbon source.And the optimal HRT and optimal carbon source dosage was analyzed.Under the guaranteeing condition that the COD of effluent was within the standard,the denitrification filters using reed straw slow-release soaking solution as carbon source maintained the best NO₃^--N removal rate when the HRT was 1h and the COD dosage was 150mg/L?C/N=5?.The nitrogen removal efficiency of three stages of the slow-release soaking solution of reed straw using as carbon source had unsignificant differences.The average removal rates of NO₃^--N were 69.71%,73.01%,and 79.30%,respectively.In order to verify the accuracy of the results,the bacterial community structure in the denitrification filters were sequenced,and different common denitrifying bacteria were found from the bacterial level,and the total abundance was more than 15%.This paper also carried out pilot-scale experiments in rural areas.The volume of pilot-scale denitrification filter is 38.92L.When HRT was 1h and the COD dosage was 150mg/L?C/N=5?,the average removal rate of NO₃^--N was 57.88%.The denitrification filter also had certain removal effects on NH₃-N and TP in sewage.Combining with the problems of storage and utilization of reed straw in the practical application process,the grinding and pelleting of reed straw is proposed.And the density of reed straw is increased by 3.02 times by grinding and pelleting.Different denitrifying bacteria were also found from the bacterial level by sequencing the bacterial community structure in the denitrifying filter.