| The addition of a large amount of heavy metals to poultry feed causes serious pollution of heavy metal in livestock manure,and which may pose a theat to soil environment and agro-product safety.Composting is not ony the important means to legalize the harmless treatment of animal manure,but also change the fraction and even to reduced the availability of heavy metals.In this paper,a new enzyme preparation was used to study the changes of heavy metal content,fraction distribution and humus content during the rapid composting of chicken manure,and therefore,it provides a reference for resource and harmlss utilization of chicken manure.(1)The chicken feces and corn stalks were used as the main raw materi als,and enzymes were added for high temperature aerobic composting experiments.The contents of p H,EC,heavy metals,morphological changes,humus content and infrared spectra were studied under different compost temperatures.The results show that compared with pre-composting,the p H value increases with the increase of temperature,and the maximum increase can be 0.53 units.The EC value did not change significantly with the compost temperature,but it was the lowest at 85 °C.Due to the decomposition of organic matter during composting,the content of heavy metals increased to different extents.The maximum increases of Cu,Zn,Cr,Cd and As were 35.6%,11.5%,35.0%,35.3% and 23.8%,respectively,compared with those before composting.However,the distribution rate of heavy metals in exchangeable state is reduced,and the distribution law of residual state is correspondingly increased.The passivation effect of heavy metals is significant at 85 °C.Compared with before composting,the passivation rates o f Cu,Zn,Cr,Cd and As are respectively 24.8%,26.0%,27.6%,26.9% and 13.9%.Under high temperature treatment,humic acid and fulvic acid vary,while the ratio of humic acid/fulic acid(HF/HA)increases with the increase of compost temperature,and the aliphatic and carboxylic acid molecules accompany the composting.Polysaccharides have increased.(2)Using chicken manure straw straw as raw material,traditional aerobic compost(VT-1000 liquid and Bacillus solid inoculant),high temperature compost(enzyme)and combined compost(traditional aerobic compost + high temperature compost)were conducted to investigate the changes of heavy metal content and morphological distribution,and the properties of organic matter.The results showed that the p H,EC and water content after composting were significantly different from those of before composting(p<0.05).The p H after composite treatment and traditional aerobic composting was significantly higher than that of high temperature enzyme compost(p<0.05),and the highest p H of 8.9 was got under the treatments of EL.However,there was no significantly different among the other treaments after the composting.The EC value of the EL group was decreased to a minimum of 2.59,and the water content after the composit e treatment was significantly lower than that of the single treatment(p<0.05).The germination index of each group was above 80%.The effectivess immobilization of heavy metals under composite treatment was better than single treatment.The stabilization rates of exchangeable Cu,Zn,Cr,Cd,Pb and As in EL group reached 69.27%,50.69%,68.67%,46.28%,54.3.% and 29.53%,respectively.Which were higher than other groups.Except for Cr and Pb,the stabilization effect of exchangeable heavy metals under traditional aerobic compost was better than that of high temperature enzyme compost.After composting,the content of humus and humic acid was increased and it exhibited significant differenc among different composting(p<0.05).The ratio of HA/FA was increased,and it was higher under the compound treatment.Infrared spectroscopy showed that the content of polysaccharides and aliphatics compounds in compost increased,but the fragrance compounds decreased.(3)Under rapid fermentation wiht high temperature,the effects of single and combined treatments of sepiolite,calcium magnesium phosphate fertilizer,and biochar on heavy metal content,morphological distribution and organic matter of chicken manure compost were studied.The results showed that the p H of each group increased after composting,and the highest p H was up to 7.09,but the EC value decreased to the lowest of 2.76,and C/N values decreased,GI was above 70%.The maximum stabilization rates of Cr,Cu,Zn As,Cd,Pb,Ni,and Mn were 37.72%,37.46%,42.22%,16.91%,18.49%,58.41%,39.18%,and 49.28%,respectively,and the highest effectiveness was obtained under the treatments of sepiolite + calcium magnesium phosphate fertilizer + biochar.The humic acid and HA increased after composting,and the hi ghest increased by 19.8% and 78.9% respectively.The FA decreased,the lowest decreased by 25.2%.Humic acid,HA,FA of each group the differences between the two groups were significant(p<0.05),but the differences between the groups were not significant.The infrared spectrum analysis showed that the content of small molecular substances of polysaccharides increased after composting.In summary,the addition of immibization agent under high temperature composting has a certain promoting effect on stabilization of heavy metals. |
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