The Emission Characteristics,Hazard Risk And Source Analysis Of Heavy Metals In End-of-life Vehicle Dismantling Plants

The metals,plastics and rubber contained in end-of-life vehicles are important secondary resources which can relief the problem of virgin mineral resources shortage and can produce considerable economic value to recycle.However,the process of end-of-life vehicle dismantling and recycling can cause some environmental pollution,and its process technology is a key factor.Therefore,this study used inductively coupled plasma emission spectrometry（ICP-OES）to analyze and determine eight heavy metals in atmospheric particulate matter,soil and water samples collected from a large end-of-life vehicle dismantling plant in China,in order to analyze the pollution characteristics and risk levels of heavy metals in different functional areas.Based on the correlation between the identified pollution sources and process characteristics,the process that needs to be upgraded is obtained,which also provides scientific data for it.The results show that:（1）In the mechanical crushing area,the average concentrations of PM2.5 and PM10exceeded the standard value seriously by 2.67 and 3.80 times,respectively.The average concentrations of Pb and Cd exceeded the secondary standard value of Ambient Air Quality Standard（GB3095-2012）.（2）The average value of Cd in rainwater exceeded the limit of the Class IV standard by1.11 times.The mean values of Pb,Cd and Fe in sewage exceeded the limit by 3.52,1.32 and3.51 times,respectively.The mean values of heavy metals Fe,Al and Cd in soil were about108.2,18.1 and 1.6 times of the background values,respectively,which might be heavily influenced by human.（3）The Cr element in the mechanical crushing area posed a certain non-carcinogenic risk to workers,and the non-carcinogenic risk posed by the other elements was negligible.Ni and Cd posed potential carcinogenic risks to workers,while Cr posed obvious carcinogenic risks to workers.（4）The deposition fluxes of heavy metals in different organs were relatively high in the mechanically fragmented zone.Zn and Pb were present in significantly higher deposition flux at three organs,and have larger deposition flux in the Nasopharynx at the mechanical crushing area.（5）The ecological risk evaluation of the dismantling plant was carried out by the single factor pollution index method,the Nemero integrated pollution index method and the potential ecological risk index method,and the results showed that Cd was heavily polluted and Pi value>3,which was the main pollution factor and the ecological risk to the soil of the end-of-life car dismantling plant was more serious.（6）The priority controlling pollutants were identified and their controlling order shall be Cd>Pb>Cr>Ni>Cu.（7）The PMF model was used to quantify and identify the sources of heavy metals in PM₁₀ and PM_2.5 in the dismantling plant,and a total of seven major sources were resolved,namely,automotive paint sources,lead-containing material sources,aluminum alloy material sources,galvanized steel material sources,electroplated nickel-chromium material sources,copper alloy material sources,and high-strength steel material sources.（8）The disassembly,crushing and cutting processes need to be optimized and upgraded through process comparison.