Study Of The Heavy Metal Deactivation Technology During Pig Manure Compost Process

A large discharge of poultry excrement has been caused environmental problem more and more seriously with its scale has been expanded and its str ucture has become more comprehensive.At the same time,because of massive heavy metal chemical additive has been used in feeding stuff,soil and environment have been seriously polluted by heavy mental which contented in poultry excrement.It has important practical significance to decline biological validity and activeness of heavy metal by deactivated processing.Pig manure has been used as compost material in this experiment,C/N ratio are regulated by straw,zeolite,sepiolite and bentonite are used as physical passivator,coal ash,calcium magnesium phosphate fertilizer, phosporite power and DBS are used as chemical passivator,each passivator establishes 3 concentration gradients(the proportions of passivator are 2.5%,5.0% and 7.5%compared with pig manure).The concentration and different forms of heavy metal has been studied in the processing of composting by simulating oxygen high-temperature composting outdoors,and then selected the best passivator of heavy metal and additive proportion.The results showed that:1.The concentrations of As,Cd,Cr,Cu,Pb and Zn have been generally increased after composting,it's obviously reflected "the relative concentration effect", but the concentration of Hg has been decreased remarkably.The validities of As,Cd, Cr,Cu,Pb and Zn have been declined by composting,so their biological validities have been decreased.On the contrary,the form of Hg has been transformed to high validity by composting,the biological validity of Hg can not be declined by compost ing.2.Different passivator has different deactivated effect for heavy metal in composting,and the effect of passivator have a great effect upon the different ratio additive proportion.Under the physical deactivate treatment,the best passivator and additive proportion of As,Cr,Cd,Cu,Zn and Pb are 7.5%zeolite,28.5%and 98.1%; 2.5%zeolite,37.5%;7.5%sepiolites,50.8%;2.5%sepiolites,72.1%;7.5%bentonite, 88.7%.Under the chemical deactivate treatment,the best passivator and additive proportion of Cu,Cr,Zn,Pb,As and Cd are 2.5%pulverized coal ash,71.5%and 77.5%;5.0%calcium magnesium phosphate,68.0%;5.0%ground phosporite,34.8%; 7.5%pulverized coal ash,10.1%;7.5%calcium magnesium phosphate,73.3%.3.Compared with contrast treatment,the content of Zn,Cu,Cd,Cr and As in Brassica sinensis L.are obviously decreased by composting of additive passivator. The variance analysis showed that,the content of As in Brassica sinensis L has remarkably different with 7.5%zeolite composting,7.5%sepiolite composting,5.0% calcium magnesium phosphate composting and 5.0%ground phosporite composting;the content of Cd in Brassica sinensis L has remarkably different with 7.5%sepiolite composting,7.5%bentonite composting and 5.0%calcium magnesium phosphate composting;the content of Cu in Brassica sinensis L has remarkably different with 7.5%zeolite composting and 7.5%sepiolite composting;the content of Zn in Brassica sinensis L has remarkably different with 7.5%sepiolite composting, 7.5%bentonite composting and 2.5%pulverized coal ash composting...