The Effect Of Sewage Sludge Biochar And Heavy Metals On The Changing Of Soil Character And Greenhouse Gases Emission

Currently,the treatment and disposal of sewage sludge had become a hot pot.It is a valuable recycling application to prepare biochar from sewage sludge and use as a soil ameliorant,which contributed to adjust the soil,remitted the pollution of heavy metals and mitigated the greenhouse gases emission.In our study,we prepared the sewage sludge carbon and added to the soil.Based on municipal sewage sludge,we prepared the biochar by the muffle furnace atmosphere.Through the single factor experiment and response surface design,examine the optimal conditions of preparation.The result of single factor experiment was that the concentration of activator was 2.5moL/L,the pyrolysis time was 2.5h,the pyrolysis temperature was 600 ? and carrier gas flow was 200mL/min.Under the result of single factor experiment,the result of response surface experiment was that the concentration of activator was 2.23moL/L,the pyrolysis time was 1.6h,the pyrolysis temperature was 581? C and carrier gas flow was 200mL/min.The optimal iodine value was 286.26mg/g.In order to investigate the effect of application of sewage sludge biochar on the changing of soil properties,the formation of heavy metals and greenhouse gases emission,the pot experiment was used.(1)The sewage sludge biochar had effect on the pH,CEC,water content,TOC,enzyme activity and so on for soil.Which improved the soil pH,from 6.19 to 7.07 and 7.45.And improved the cation exchange capacity,which indicated the retention of water and fertilizer was improved.As the above conclusion the water content,TOC and N nutrient were higher than the control group.The change of soil was conducive to the soil microorganism,whose number and enzyme activity was stronger.Adding the proportion of 5%and 10%of sewage sludge biochar,compared with the control group,the accumulation of CH4 emission decreased by 92.11%and 92.11%respectively;The accumulation of N2O emission decreased by 82.90%and 82.90%respectively.(2)When the soil was polluted by heavy metals,which will affect the soil microorganism and greenhouse gases emission.The pollution of Cd and high concentration of Cu and Zn reduced the number of bacteria,on the contrary the low concentration of Cu and Zn promoted the breeding of bacteria.The pollution of heavy metals had bad effect on the fungus.The catalase activity were improved by the pollution of heavy metals.Forthe urease activity,which was strengthened by the Zn,the Cd and Cu were opposite.Different parts of rice for enrichment of Cd,Cu and Zn were for the mass fraction of the size of the root>stem>leaf.For emissions of N2O,the pollution of 100 mg/kg Cu promoted it,the rest of the treatment group are inhibiting.For emissions of CH4,Zn had a promoting effect,and showed inhibitory effect on Cd and Cu.(3)When the biochar and heavy metals in the soil,the exchangeable of heavy metals was significantly reduced and the residual form augmented.For the greenhouse gases emission,the biochar was dominated.