The Heavy Metal Content Of Rural Living Garbage And The Environmental Risk Research Of The Process Of Landfill

Our rural areas are popular,as the amount of rural domestic wastes increases,the harm of domestic wastes heavy metals,in order to know about the pollution characteristics and degree of heavy metal of rural domestic wastes in China,in 72 typical villages and towns chosen from 12 provincials,rural domestic wastes sampling and survey have been done in four seasons,meanwhile,the environmental risk is evaluated;study the collection frequency and effects on heavy metal content in rural landfill wastes leachate by wastes landfill structure;set up environmental risk evaluation model of heavy metal leachate,thus to predict and evaluate the environmental pollution risks by leachate heavy metal in different landfill scale of rural wastes,and the main study results are as follows:(1)The heavy metal contents of typical rural domestic wastes are lower comparatively,the contents of heavy metals are Cr>Zn>Cu>Pb> As>Cd>Hg,among which,the contents of As,Hg,Pb,Cd,Cr,Cu and Zn are 7.65±8.73?0.74±0.48?21.80±17.61?3.36±11.01?108.632±84.011?36.83±10.91 and 80.09±42.24 mg·kg-1respectively.Except for Cu in typical rural domestic wastes of China,As,Hg,Pb,Cd,Cr and Zn are all affected a lot by seasons,the heavy metal contents of typical rural domestic wastes in spring are the highest;the As,Pb and Cu contents in our north and south typical rural domestic wastes are different from each other slightly,while Hg,Cd,Cr and Zn are different obviously,in general,the heavy metal contents of typical rural domestic wastes in northern areas are lower than those in southern areas;the heavy metal contents of typical rural domestic wastes as As,Hg,Cd and Cr aren't different a lot,but the Pb,Cu and Zn are different obviously in two areas;the heavy metal contents of typical rural domestic wastes are different obviously in different areas of China;the rural domestic wastes are nutrients to some extent,and they content comparatively low heavy metal contents,so they have great potential for compost.(2)It can be seen from the average value P of single factor pollution index,the pollution degree of typical rural domestic wastes heavy metals: when Cd>Hg>Cr>Cu>Zn>As>Pb,PCd>3 is heavy pollution,PHg>1 is slight pollution,and other heavy metals are not pollutants.The Nemerow Pollution Index P of typical rural domestic wastes heavy metalsis 4.85,which is heavy pollution,and contributed the biggest by Cd,followed by Hg.The potential risk degree of seven kinds of heavy metal pollution of typical rural domestic wastes is: Cd>Hg>Cu>As>Pb>Cr>Zn,while Cd and Hg have stronger and strong ecological potential respectively;the complex potential ecological risk index is345.55,a strong potential ecological risk.(3)In general,after 7d and 15 d simply composting for rural domestic wastes,the dissolution concentration of heavy metal in domestic wastes can rise,as for simple compost,30 d can decrease the dissolution concentration of heavy metal,therefore,the domestic wastes in rural areas are to be carried away 1 time/3 days,or 1 time/30 days,but ensure there are proper storing facilities,to prevent leaching by rains;as for areas where domestic garbage is polluted severely by Cr,Ni and As,it should be buried anaerobic;as for areas where domestic wastes are polluted severely by Cd and Pb,the wastes should be buried in an aerobic method;and areas polluted by wasted containing Cu,then wastes can be buried in both methods.(4)It shows by combing the inspection result of rural domestic wastes landfill leachate as well as the simulation result of model,if rural domestic wastes landfills are set in village-level,township-level and town-level,then the village-level landfill can be single-layer clay permeation-resistant system,and township-level domestic wastes landfill can be single-layer HDPE film impermeable system,and town-level domestic wastes landfills can be double-layer HDPE film impermeable system.Meanwhile,considering the different regions in China,if township-level rural domestic wastes landfills are set in different demonstration points respectively from west to east,then the township-level rural domestic wastes landfill in Pengyuan township Gansu should be clay impermeable system,and single-layer HDPE film impermeable system for township-level rural domestic wastes landfill in Tiemen Hubei province,and double-layer HDPE film impermeable system for township-level rural domestic wastes landfill in Shuxin,Shanghai.