Effect Of Vermicompost On Ammoniation And Nitrification In Sewage Sludge

Vermicompost has been a research hotspot in recent years because of its high practical value,and it was the main product after vermicomposting.Based on previous research,vermicompost has a significant role in the stabilization of sludge compost,and it can quickly stabilize the organic matter of sewage sludge.According to mineralization of organic nitrogen,we found that the nitrogen in the sludge after the addition of vermicompost was mostly stored as ammonia nitrogen,but the nitrate nitrogen content was low.In order to understand the reaction mechanism of mineralization of organic nitrogen,This paper analyzes the conversion of organic nitrogen during the stabilization of sewage sludge by vermicompost through comparative experiments,included the changes in the content of ammonia nitrogen,nitrate nitrogen and accumulation rate.Monitor the physical and chemical indicators related to nitrogen transformation,micro-animals and other factors to analyze to explore the reasons for the differences in nitrogen forms in sludge.The purpose of this study was to study the effect of vermicompost on the ammoniation and nitrification of organic nitrogen mineralization in sludge.The results show that:1.Vermicompost significantly promoted the mineralization of nitrogen in sludge?p<0.01?.At the end of the experiment,total nitrogen?TN?in the treatment group was 17.6%lower than that in the control group.The correlation analysis results showed that the total nitrogen?TN?in the treatment group was significantly positively correlated with water-soluble organic carbon?WSC?and organic matter?OM?with correlation coefficients of0.88 and 0.99,respectively.The addition of vermicompost can significantly promote the degradation of organic matter?OM?and water-soluble organic carbon?WSC?.The decomposition of amino acids and protein-containing nitrogen-containing organic matter in organic matter?OM?will cause rapid mineralization of nitrogen,which in turn promotes sludge Ammonia nitrogen formation.Otherwise,the pH in the treatment group was 0.2-0.3higher than that in control group.The degradation of the organic carbon in the sludge produced acid that caused the pH value of the sludge in the control group to decrease by 0.2pH on the 8th day of the experiment when experiment beginning,and the pH of the treatment group remained unchanged.After that,the pH value of the treatment group and the control group gradually increased with time.The pH environment of the treatment group is more suitable for the survival of ammoniated bacteria,so the ammonia nitrogen in the treatment group sludge accumulates quickly.With the continuous progress of ammoniation,the pH environment in the sludge also continues to increase.2.Effect on the increase of ammonia nitrogen in the sludge,we found that vermicompost has a significant promotion,and the accumulation rate of ammonia nitrogen reached the highest(22mg/kg·d^-1)at 48 days.The highest difference was 361 mg/kg between on two different treatments.The ammonia nitrogen of the treatment group was 619 mg/kg when the experiment end.The RDA analysis found that nematodes and ammonia nitrogen was a close relationship in the main micro-animal populations.The number of nematode populations in the sludge increased after the addition of vermicompost,and it was five times that of the control group.We found that the nematodes were mainly bacterial food at this time by microscopic observation.The number of microorganisms in the treatment group is higher than that in the control group when the nematode populations numbers increase in treatment group.Ammonia nitrogen in the sludge accumulate rapidly with the number of nematodes began to decrease,indicating that the ammoniation was enhanced at this stage.3.Vermicompost had no significant effect on nitrate nitrogen,and the nitrate content began to increase at 40 days.The nitrate nitrogen accumulation rate of the control group was significantly higher than that of the treatment group?p<0.01?until the experiment end,and the content was twice that of the treatment group.The results of redundancy analysis?RDA?showed the number of micro-animals capable of indicating the process of nitrification was higher in the control group when after nitrification in the sludge.From the nitrate content found in the control group the same nitrate content than treatment group,thus reducing the added sludge after nitrification vermicompost,and transferred to a portion of the ammonia nitrogen in the nitrification vermicompost.In sum up,vermicompost has a significant effect on the nitrogen conversion form of sludge,and its promotion of ammoniation is the most obvious.The addition of vermicompost can promote the rapid mineralization of organic matter in the sludge,and then promote ammonia nitrogen.On the other hand,the adsorption of vermicompost can reduce the conversion loss of ammonia nitrogen in the sludge.However,the excessive accumulation of ammonia nitrogen by vermicompost will inhibit the normal progress of nitrification.