Effects Of Wood Vinegar And Biochar On Aerobic Pile Composting Of Pig Manure

The intensive degree of pig breeding is becoming higher and higher.If the manure is not handled properly,it will lead to environmental pollution and waste of resources.Aerobic compost is one of the effective ways to deal with pig manure.The development of aerobic composting technology is relatively mature,but it has not been used much in southern Xinjiang.In this paper,pig manure was used as the research object in Happiness Farm,the First Division of Southern Xinjiang.Strip aerobic compost composting was carried out,and wood vinegar and biochar were added in the composting process to study its synergic effects on compost maturation and heavy metal passivation.(1)Based on the semi-fermented pig manure strip composting experiment of wood vinegar and biochar,chemical experiments were used to detect and analyze the physical and chemical properties of materials and the total contents of heavy metals Cu and Zn in the composting process.The research showed that the composting temperature rose first and then decreased with the composting time,and the high temperature period of composting could reach 65℃.The warming rate of wood vinegar reactor is higher than that of biochar reactor.In the composting process,the water content,organic matter and C/N decreased with the change of composting time.The organic matter content of wood vinegar pile was 54.10%,and that of biochar pile was 46.84%.The nitrogen content of wood vinegar reactor and biochar reactor increased by0.12% and 0.08%,respectively,compared with that before composting.At the end of the wood vinegar reactor and the biochar reactor,the C/N values were 20.99 and 17.21,respectively.The contents of heavy metals Cu and Zn in biochar heap were 149.28mg/kg and 702.35mg/kg,while those in wood vinegar heap were 148.25mg/kg and 716.47mg/kg.There were significant differences in the compost decomposition characteristics between biochar and wood vinegar(P<0.05).(2)Based on the experiment of strip composting of unfermented pig manure by aerated wood vinegar and biochar,the design of composting aeration device was applied in strip composting aerobic composting,and pig manure composting was carried out in three groups with different amounts of biochar Tc1～Tc3 and three groups with different amounts of wood vinegar Tm1～Tm3.The results showed that at the end of composting,the average water content of the biochar experimental group was 42.53%,and the average water content of the wood vinegar experimental group was 42.77%.By using BCR extraction method,the total content of heavy metals Cu and Zn and the content of different forms of the compost samples were detected.The results showed that,The passivation efficiency of Cu and Zn in all experimental groups was higher than that in CK group.Tm1 group was the best experimental group.The passivation efficiency of Cu in Tm1 group was the highest 44.02% and that of Zn was the highest 41.77%.The humus changes at each stage of compost were detected by chemical method.The humus degree of Tm1 group was the highest,and that of wood vinegar solution was higher than that of biochar group.The germination rate experiment showed that the GI value of Tm1 group was 104%.(3)The results showed that the temperature of semi-fermented pig manure compost was positively correlated with water content,pH,EC,organic matter and C/N,and negatively correlated with the total content of Cu and Zn in the compost.There was no correlation between the pH of wood vinegar and heavy metals Cu and Zn in unfermented pig manure compost(P>0.05).The temperature of unfermented pig manure compost was positively correlated with water content,pH,organic matter,nitrogen content and C/N parameters,while the temperature was negatively correlated with EC,Cu and Zn contents.There was a significant positive correlation between the exchangeable states of Cu and Zn in unfermented pig manure compost by means of biochar and wood vinegar(λ=0.948,P<0.01;λ=0.878,P<0.01;λ=0.969,P<0.01;λ=0.968,P<0.01);There was a significant positive correlation between the hu-richness ratio of biochar and wood vinegar groups and the residue state(λ=0.976,P<0.01;λ=0.97,P<0.01;λ=0.961,P<0.01;λ=0.931,P<0.01),the humification was positively correlated with the exchangable state of heavy metals.The higher the degree of humification,the better the passivation effect of heavy metals.