The Effect Of Aerobic And Anaerobic Treatment On The Bioavailability Of Heavy Metals In Pig Manure And The Selection Of Passivation Materials

In this paper,aiming at the key problem of whether heavy metals exceed the standard in the resource utilization of pig manure,the contents of heavy metals in aerobic composting and anaerobic fermentation of pig manure in pig farms were investigated.under the simulation experiment,the difference of heavy metal content and availability of pig manure treated by aerobic composting and anaerobic fermentation was carried out,on the basis of which the screening test of heavy metal passivators（activated carbon,diatomite,chitin）for anaerobic fermentation of pig manure was further carried out.To explore the ways to solve the problem of heavy metal pollution in aquaculture manure,in order to provide scientific basis for green disposal and utilization of aquaculture manure.The main results are as follows:（1）The contents of Cu and Zn in the manure of pig farms in the study area mainly exceeded the standard,and the content ranges were 88.90 mg·kg^-1～575.60 mg·kg^-1,70.16 mg·kg^-1～3146.98 mg·kg^-1.the contents of As,Cr,Pb,Cd and Ni were lower,and all met the organic fertilizer nutrient standard NY525-2012.The content of Cd in manure was 0.16 mg·kg^-1～1.63 mg·kg^-1,which was not the main heavy metal pollutant in pig manure.（2）After aerobic composting and anaerobic fermentation,the total contents of Cu,Zn and Cd in pig manure increased significantly,showing an obvious"concentration effect",while the contents of available Cu and Zn did not increase significantly after aerobic composting and anaerobic fermentation,especially the proportion of DTPA extracted state decreased.Under aerobic composting,the percentage of DTPA extracted Cu in pig manure decreased from 25.20%to 22.03%,the proportion of DTPA extracted Zn decreased from 39.64%to 24.23%,and DTPA extracted Cd decreased from 39.64%to 24.23%.Under the treatment of anaerobic fermentation,the proportion of DTPA extracted Cu in pig feces decreased from 25.20%to 8.72%,and the DTPA extracted Zn decreased from 39.64%to 28.37%,and the DTPA extracted Cd decreased from 44.04%to 42.62%.In the process of anaerobic fermentation,with the extension of fermentation time,the total amount of Cu,Zn and Cd in pig manure increased as a whole,while the content and proportion of available Cu,Zn and Cd in DTPA decreased obviously.The anaerobic fermentation process and the extension of fermentation time can effectively inhibit the activity of typical harmful heavy metals（Cu,Zn,Cd）in pig manure.（3）The addition of chitin can obviously activate Cd,Zn and Cu,in pig manure,and the addition of diatomite can passivate Cu,in pig manure.Activated carbon can effectively passivate the typical heavy metals（Cu,Zn,Cd）in fermented manure.With the addition of activated carbon,the contents of DTPA available Cd,Cu and Zn in pig manure were reduced to 21.64%,9.29%and 28.28%,respectively.In this study,activated carbon was selected as the passivator which can effectively inhibit the activity of typical heavy metals（Cu,Zn,Cd）in pig manure under the condition of anaerobic fermentation.