Dezhi Shi

Heavy metal and persistent organic compound contamination in soil from Wenling: an emerging e-waste recycling city in Taizhou area, China.

The present study was conducted to investigate the levels and sources of heavy metals (Cu, Cr, Cd, Pb, Zn, Hg and As) and persistent organic compounds including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in soils taken from Wenling, an emerging e-waste recycling city in Taizhou, China. The results suggested that most heavy metals exceeded the respective Grade II value of soil quality standards from State Environmental Protection Administration of China and also exceeded the Dutch optimum values. Total PAHs in soil ranged from 371.8 to 1231.2 microg/kg, and relatively higher PAHs concentrations were found in soils taken from simple household workshops. PCBs were detectable in all samples with total concentrations ranging from 52.0 to 5789.5 microg/kg, which were 2.1-232.5 times higher than that from the reference site (24.9 microg/kg). Results of this study suggested soil in the Wenling e-waste recycling area were heavily contaminated by heavy metals, PAHs and PCBs. Furthermore, compared with large-scale plants, simple household workshops contributed more heavy metals, PAHs and PCBs pollution to the soil environment, indicating that soil contamination from e-waste recycling in simple household workshops should be given more attention.

Effects of bamboo charcoal and bamboo vinegar on nitrogen conservation and heavy metals immobility during pig manure composting.

Composting is an effective methodology for the treatment of organic waste like pig manure (PM) before land application. However, nitrogen loss through NH(3) volatilization during the thermophilic phase is one of the major disadvantages of composting. The presence of Cu and Zn in compost arising from pig feed additives is also an issue. In this study the effects of bamboo charcoal (BC) and bamboo vinegar (BV) added to composting piles on nitrogen conservation and immobility of Cu and Zn during PM composting was investigated. Total Kjeldahl nitrogen (TKN) loss and mobility of Cu and Zn decreased with increased BC addition. TKN loss and mobility of Cu and Zn in the treatment with 9% BC at the end of composting significantly decreased by 65%, 35% and 39% respectively, as compared to the control. Addition of BV further decreased TKN loss. After composting, TKN loss in the treatment with 3% BC+0.4% BV was 23% lower than that in the treatment with 9% BC. The final results indicated that by adding BC or BC+BV into PM composting is an effective method to reduce TKN loss and control the mobility of Cu and Zn.

Levels and patterns of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in municipal waste incinerator bottom ash in Zhejiang province, China.

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were analyzed in bottom ash from municipal solid waste (MSW) incineration in six cities in Zhejiang province, where one-fourth of the MSW incinerators of China are located. Total PAH contents varied from 2222.53 to 6883.91 microg/kg. The patterns of PAHs were found to be very similar in all the samples, dominated by three-ring and four-ring PAHs. Total PCB concentrations in bottom ash ranged from 1.00 to 1.31 microg/kg, while the coplanar PCBs in the bottom ash were in the range of 0.08-0.52 microg/kg. Among PCB congeners, low chlorinated PCBs contributed to the majority of total PCBs. Generally, PAH concentrations in cities with fluidized bed incinerator were less than those in cities with grate furnace incinerator. PAH and PCB levels were affected by both plastic content in MSW incinerator feed and combustion efficiency. However, further study is required to investigate the effect of these two variables deeply, as well as other influencing factors.

PCB congeners induced mitochondrial dysfunction in Vero cells

Two PCB congeners were assessed for their cytotoxicity on Vero cells, in the attempt to compare their structure-activity relationship and to investigate the role of mitochondria involved in toxicity. Flow cytometry was used to monitor the changes of mitochondrial membrane potential (Δψ(m)), cell size and apoptosis rate. Treatments of Vero cell cultures with both PCB 126 and PCB 153 resulted in loss of cell viability in our experimental conditions. In ortho-substituted PCB 153 treated cells, loss of cell viability was accompanied by decreased Δψ(m) and cell shrinkage. The coplanar congener, PCB 126, had no significant effects on Δψ(m) or cell size in this time period of exposure. These studies showed that PCB 153 is more toxic than coplanar PCB 126 to Vero cells within 24h exposure. The cytotoxicity mechanism caused by coplanar or non-coplanar PCB congener was different, and apoptosis might be the main cell death pathway in PCB 153 treated cells.

Performance evaluation of biofilters and biotrickling filters in odor control of n-butyric acid

With the rapid development of swine production in China, odor pollution associated with piggery facilities has become an increasing environmental concern. N-butyric acid (n-BA) is one of the key odor compounds selected to represent volatile fatty acids (VFAs) found in piggery facilities. In this study, two biofilters (BFs) packed with compost (BFC) or sludge (BFS) and two biotrickling filters (BTFs) packed with pall rings (BTFP) or multidimensional hollow balls (BTFM), respectively, were compared with regard to their performances in the removal of n-BA. The non-biological removal capacities of packing material of the bioreactors on a per unit volume basis were BFS>BFC>BTFM>BTFP. Maximum biological removal capacities per unit volume of packing material of the bioreactors all exceeded 9.1 kg/m3·d and in the order of BFC>BTFM>BFS>BTFP. Kinetic analysis as well as overall evaluation by radar graphs showed that the BTFs achieved superior removal rates to the BFs in the order of BTFM>BTFP>BFC>BFS. The biotrickling filter packed with multidimensional hollow balls could be an effective technology for VFAs removal. Results from this research provide economical and effective alternatives for odor control in piggery facilities.