Environmental Assessment Of Mechanical-physical Method For E-waste Recycling In And Around The Workshops

With the rapid development of electronic information technology, the upgrading of electricaland electronic products will produce large amounts of electronic waste (e-waste). How toimplement resource recovery and harmless of e-waste is being widely concerned by the society.Presently, mechanical–physical technology has been widely used in e-waste recycling factories inChina, which includes manual dismantling and mechanical separations of printed circuit boards(PCBs) and cathode ray tubes (CRTs), with the advantages of high efficiency, low cost and lowpollution. However, considering the toxic substances in e-waste, this technoloty will also causeenvironment pollution in and around the workshop, but there is no relevant research about thenoise level, the diffusion of CFC-11, the distribution characteristic of particulate matters andheavy mentals around the e-waste recycling production lines. So in this study, a typical e-wasterecycling factory was chosen to assess the environmental impact from waste television andrefrigerator recycling processes, which has the qualification certificate conferred by the China’sMinistry of Environmental Protection. The nosie level and mean concentrations of CFC-11,particulate matter and heavy metlas has been monitored and environmental impact has beenevaluated by the models of noise control, Gaussian dispersion and health risk assessment.For waste television recycling line, the monitoring results show that the noise level indismantling workshop was81.3dB, which met the environmental standard (GBZ2.2-2007,85dB).But the noise level in printed circuit boards (PCBs) and cathode ray tubes (CRTs) recyclingworkshops were94.7dB and93.9dB, respectively, which obviously exceeded this standard. Themean concentrations of particulate matters (TSP、PM10、PM2.5) in these three workshops alsoexceeded the threshold prescribed by GB3095-2012, and fine particles had a larger proportion.Distribution regularities of heavy metals in different diameter particles were as follows: Cr, Ni andPb tended to adsorb on fine particles, Cu and Cd had a higher concentrations in coarse particles;Cu had maximum contents in both dismantling and PCBs recycling workshops, the concentrationof Pb was highest in CRTs recycling workshop, and the contents of Cd were lowest in theseworkshops. After calculation, PM2.5and PM10in these workshops might have non-carcinogenicrisk, but Cr, Ni and Cd were not carcinogenic.For waste refrigerator recycling line, the acoustic hood had a significant reduction effect onnoise, CFC-11, particulate matter and heavy metals. For noise, the decreasing result was17.5dBwhich reduced the nosie level (78.9dB) in the workshop under the threshold of noise. For CFC-11, the average concentration was lessened from255mg/g3in acoustic hood to0mg/g3in theworkshop because of acoustic hood. For particulate matter, the reduced proportion of the contentreached to40-50%by use of the acoustic hood, but the concentration of particles in the workshopalso exceeded the standard prescribed by GB3095-2012. The acoustic hood had little effect on thechange of heavy metal concentrations. According to the calculating result, it can be seen thatPM2.5and PM10had the non-carcinogenic risks on the workers, however, there is no cancer riskabout Cr, Ni and Cd.Around the factory, the noise level ranged from63.4dB to64.5dB, all of which below thenoise threshold (70dB) prescribed by GB12348-2008. The mean concentrations of particulatematter in downwind direction was obviously higher than that in upwind direction, especially PM2.5and PM10, which indicated that fine particles in the workshop had a harmful impact on the airaround the factory. The analysis of particulate matter in downwind direction showed that Pb wasthe most enriched metals followd by Cr, Ni and Cu, and the content of Cd was the least. Aftercalculation, PM10in downwind direction had the non-carcinogenic risk. However, PM2.5had nopossibility of non-carcinogenic risk, and also Cr, Ni and Cd had no probability of cancer risk.In short, the research results show that mechanical–physical process for e-waste recyclingdo exist the pollutant emission. So the effective measures should be taken to reduce the harm ofpollutants on the workers’ health. For example, the technologies of sound insulation, soundabsorption and noise elimination could be used in crush–separation facilities, and efficientfiltering technologies can be adapted to strengthen the removal of fine paticles, such as Teflonfabric filtration systems. Meanwhile, higher automation degree of facilities and production linesshould be reinforced constantly to cut down the exposure duration of workers. All those measurescould ensure the workers’health and realize resource recovery and harmless of e-waste. Moreover,experimental results were the effective reference basis for the China State EnvironmentalProtection Department to develop the relevant laws like―air pollutants and noise emissionstandards in electronic waste recycling industry‖.