Research On Composting Treatment Of Waste Mushroom Residue And Its Application In Remediation Of Oil-Contaminated Soil

With the edible mushroom market increasing year by year and the popularization of edible mushroom factory production technology in recent years,China has become one of the largest edible mushroom producers in the world,and the edible mushroom industry has become the fifth largest cultivation industry in China,however,a large amount of mushroom residue is not effectively used in actual production,and most of them are directly discarded or burned,which not only pollutes the environment but also wastes resources.Therefore,it is especially important to use mushroom residue scientifically and reasonably,so as to turn it into treasure and promote the healthy and sustainable development of edible mushroom industry.In this paper,starting from the selection of composting additives and the screening of composting bacterium,the following conclusions were reached through the study of the effects of different additives on the composting of waste mushroom residues and the application of composting products in the remediation of petroleum-contaminated soil:15 strains of Bacillus sp.were isolated from cattle gastric juice,and 1 strain of yeast was isolated from white wine lees;for the 16 isolated strains,the ratio of clear circle diameter to colony diameter and enzyme activity of fibrous screening medium were determined,and the D/d value of strain W7 was 5.67,and the cellulase activity value was 61.15±3.12 U/mL,which was significantly higher than other strains and had the strongest degradation ability of cellulose;strain W6 had a D/d The D/d value of strain W6 was 3.29 and the protease activity value was 144.21 ± 7.66U/mL,which was significantly higher than other strains and had the strongest protein degradation ability;the D/d value of strain W4 was 2.69 and the amylase activity value was 114.53 ±1.74U/mL,which had the strongest starch degradation ability.The antagonism experiment showed that all the three strains were free of sterile zone and had the prerequisites for the preparation of the mixed bacterial agent.By measuring the cellulose,protein and amylase activities of the hybrid and single strains,it was found that the cellulose enzyme activity of W4+W6+W7 hybrid was 70.75 U/mL,the protein enzyme activity was 173.25 U/mL and the amylase activity was 129.84 U/mL,which showed a significant increase compared with the three single strains,so it was finally determined that the hybrid could be used as an exogenous composting bacterial agent.The composting process was carried out by using the obtained composting bacterium to compost the waste mushroom residue,and the pure mushroom residue was used as the control experiment(CK)with three treatments of mushroom residue +composting bacterium(SC),mushroom residue + chicken manure(SG)and mushroom residue + composting bacterium + chicken manure(SW).The results showed that the addition of chicken manure and composting agent played a significant role in promoting the composting of waste mushroom residue.The temperature of SG and SW treatments was above 50℃ for 5 and 2 d,respectively,indicating that the addition of chicken manure helped to warm up the mushroom residue compost,while the temperature of the two composting treatments without the addition of chicken manure did not reach 50℃,but the overall temperature of SC treatment was higher than that of CK,indicating that the addition of the mixture also helped to warm up the mushroom residue compost.The water content of the compost was similar in all four treatments,the p H was in accordance with the microbial growth requirements,and the conductivity of the products of SG and SW groups was in accordance with the normal range for plant growth.The有机质and total nitrogen of all treatment groups showed a trend of reduction,the有机质degradation rate of SW,SG,SC and CK treatments were 13.7,22.4,13.2and 12.1%,and the total nitrogen degradation rate was 71.6,73.0,63.5 and 57.2%,respectively,and the product C/N of all four treatment groups was greater than before composting,the ammonium nitrogen and nitrate nitrogen of all treatments showed a trend of first increase and then decrease.The overall DOC content of the SW and SG groups showed a trend of increasing and then decreasing,and reached the highest value in the high temperature period,with the highest value of 81.63 mg/kg and 86.21 mg/kg,respectively,while the SC and CK groups showed an overall decreasing trend,and the DOC content of the SC group decreased less.The overall number of microorganisms in SC,SG and SW treatments was higher than that in CK;the GI of compost final products in CK,SC,SG and SW groups were 4.5%,27.3%,71.8%and 59.1%,respectively,and the compost products in SG and SW groups were basically decomposed,as indicated by the results of three-dimensional fluorescence spectroscopy,it was found that the fluorescence intensity of SC,SG and SW treatment products was significantly enhanced compared with that of pre-composting class humic substances This indicates that active humification reactions were carried out in the piles,and the final product humus-like substance concentration CK≤SC≤SW≤SG.The obtained compost products were used to remediate the petroleum-contaminated soil,and the petroleum-contaminated soil was used as a control experiment during the remediation process.The results showed that the addition of compost products to the petroleum-contaminated soil contributed to the degradation of petroleum hydrocarbons in the soil,and the degradation efficiency was positively correlated with the degree of organic fertilizer decomposition.Compared with the unremediated soil at 60 d,the removal rates of total petroleum hydrocarbons increased by 10.70%,9.23%,18.62%,22.9%,alkanes by 9.05%,10.84%,14.31%,11.59%,and PAHs by 2.95%,6.49%and 3.9%,respectively,when CK,SC,SW and SG compost products were added to the soil.This indicates that the mushroom residue compost product can be used for the remediation of petroleum-contaminated soil,and the removal of alkanes is the most obvious.The有机质,total nitrogen,total phosphorus,ammonium nitrogen and nitrate nitrogen in the compost products improved the physicochemical properties of the soil and increased the activity of soil microorganisms,which in turn degraded the soil petroleum hydrocarbons.