| The problem of garbage in suburban area can’t be neglected with rapid urbanization. Because of climate, lifestyles, living standard and economic level, the characteristics of domestic garbage should be different in different areas, thus the garbage in suburban area should differ from that in downtown, and rural areas. It is important to understand the properties of suburban garbage accurately before scientific classification, management and treating. However, the differences of the domestic garbage from the mentioned three areas have hardly been compared in articles. Thus, this article took the suburban garbage of Chengdu as main research object and compared its water content, physical components, caloric value, heavy metal pollutants etc. with those in the downtown and rural garbage of Chengdu. Considering the different properties of suburban garbage, we provide a feasible suggestion for suburban garbage treatment. The results of this study are as follows:(1) Moisture content of the garbage was between 47.8%-64.2%. The moisture content of suburban garbage was the lowest among the three,but was higher in summer (54.0%-59.8%)than that in winter(47.8%-54.1%); that of downtown garbage was relatively high and stable in winter and summer (57.2%-63.1%); that of rural garbage was the highest in summer (59.4%-64.2%).(2) In the aspect of physical composition, kitchen waste was the highest component in all areas and its quantity in winter was higher than that in summer of the same area. Compared with the kitchen waste from suburban and rural areas, the quantity of it in downtown was higher both in summer and winter, which reached to 66.6%. Besides kitchen waste, the main components in suburban garbage were dust (15.3%-27.6%), non-recyclable plastics, meal paper and packaging paper; and those in downtown garbage were non-recyclable plastics (6.8%-16.5%), meal paper, dust and wrapping paper; and those in rural garbage were dust (4.0%-31.4%), non-recyclableplastics, mealpaper and leaves.(3)This study investigated the properties of domestic waste in suburban, downtownand rural areas of Chengdu in summer and winter. It was found that most heavy metal concentrations went beyond the level of local soil background in domestic waste of Chengdu and that heavy metal concentrations were greater in summer than winter. Both in summer and winter, Se, Cd and Cu were the severe pollutants of domestic waste in all areas of Chengdu, and their concentrations were 0.3-1.1mg/kg, 0.3-0.9mg/kg and 24.9-152.6mg/kg, respectively. Other heavy metal pollutants (for example, Pb, Hg and Cr) were of different polluting improtance for the three areas. Heavy metal source analysis of domestic waste in the three areas was explored by Pearson correlation and principal component analysis. The results showed that Cd was mainly from kitchen waste, dust and plastics, Se might came from electronic waste; Cu and Zn were from dust and printed matter; Pb in downtowngarbage was mainly from dust, plastics and printed matter.In suburban domestic waste, Cr and Se were mostly from dust, and Hg was mainlyfrom kitchen waste and dust. Cr in rural garbage was mainly from wastewater irrigation.(4) The suburban garbage showed a high proportion of compostable components and a low content of flammable components and dust component which got a high proportion in suburban garbage was rich in heavy metal. Therefore, it is suggested that under the control of heavy metal pollution, the kitchen waste, meal paper and leaves components are collected together for resource utilization; unrecyclable plastics, packaging paper and dust component are collected for sanitary landfill; recyclable components are reused. |
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