Study On The Treatment Of Phosphogypsum By Using Pig Manure And Fungus Sticks To Raise Earthworms

With the rapid economic development,the production of livestock and poultry manure,agricultural waste fungus sticks and solid waste phosphogypsum in the production process of planting,breeding,and phosphate chemical industries is increasing.Improper disposal of these pollutants will not only cause Bring serious environmental pollution problems and waste of resources.How to effectively use livestock and poultry manure,fungus sticks and phosphogypsum to develop a circular economy has received widespread attention from the society.The conventional high-temperature composting method has problems such as stacking environment,composting temperature,and unstable properties of the finished product after composting,which hinders the promotion of this method in various regions to a certain extent.In order to solve this problem,this experiment uses vermicompost to treat pig manure,fungus sticks and phosphogypsum to study the physical and chemical properties of the vermicomposting process under different material ratios,the activity of related enzymes,and the content and composition of heavy metals before and after the vermicompost.Optimize the process parameters of vermicomposting to provide theoretical and technical support for the resource utilization of solid waste.The test results are as follows:Vermicompost can effectively reduce the p H of each component,making the p H of the compost gradually neutral.At the end of the experiment,the p H of the 4 test groups is between 7.2 and 7.5;the final organic matter content of each test group is reduced 25%or less,effectively improve the stability of the material,and when the content of phosphogypsum is between 5%and 10%,the decomposition rate of organic matter can reach 66.28%;the relevant indicators of nitrogen,nitrate nitrogen,phosphorus and potassium（TP,TK,available phosphorus,quick-acting potassium）the final content increased,when the addition of phosphogypsum was 20%,the TN content in the compost increased most obviously,reaching 250%;the final nitrate nitrogen content of each test group was high At 0.8g/kg,and the ammonia nitrogen content decreased significantly;but the growth rate of phosphorus and potassium related indicators（TP,TK,available phosphorus,quick-acting potassium）content in all experimental groups was between 20%and 30%.The difference is not obvious.Experiments show that the addition of phosphogypsum effectively promotes the accumulation of TN,NH₄⁺,TP,available phosphorus,TK and available potassium in the vermicompost product,and significantly increases the land use value of earthworm manure.After 56 day vermicomposting process,the activities of catalase,urease and alkaline phosphatase decreased in the middle of the experiment,but they all rebounded in the latter part of the experiment.The growth rate of catalase in each experimental group was lower than 31.64%in the CK group;the growth rate of urease in each experimental group was 407.92%,but the growth rate of CK group reached 688.19%,indicating that phosphogypsum The activity of catalase and urease were inhibited,and the inhibitory effect on urease activity was more significant.For alkaline phosphatase,the activity of alkaline phosphatase in the test group added with phosphogypsum increased.And when the content of phosphogypsum accounted for10%of the total mass of the compost,the activity of alkaline phosphatase increased most significantly,reaching 263.52%.For the heavy metals in the composting process,the content of Cu,Cd and As in the compost will increase in the compost due to the"concentration".For the change of the total content of Cu,the growth rate of the CK group reaches 36.94%.The addition of gypsum will reduce the growth rate of the total content of Cu in the compost by3%-9%,but its total content still shows an upward trend in all composts,and the growth rate of the total content of As is as high as 44.18%;while Pb Due to the"dilution effect",the content of Pb and Cr will show a downward trend in the compost.The reduction rate of the total content of Pb reaches 26.30%,and the highest reduction rate of the total content of Cr reaches 46.11%.At the end of the test,the total content of the five metals did not exceed the limit index requirements for heavy metals in organic fertilizers as required by the National Standard for Organic Fertilizers（NY 525-2012）.The changes in the form of heavy metals indicate that the addition of phosphogypsum will also reduce the available content of heavy metals Cu and Pb.Among them,the available content of heavy metal Cu decreases significantly,and its available state can reach 17.8%at least,compared with CK For the heavy metal Cr,when the amount of phosphogypsum accounts for more than 10%of the total mass of the compost,the content of the heavy metal Cr available will be significantly reduced,and it can reach 8.15%at the lowest point,which is 7.03%less than the CK group;When the amount of phosphogypsum added is 5%of the total mass of the compost,the available content of heavy metal As will eventually be reduced to 13.07%,but the available content of the other test groups will be somewhat different than that of the CK group.increase.