Removal of polybrominated diphenyl ethers in high impact polystyrene (HIPS) from waste TV sets.

Most studies have shown that improper disposal of e-waste can accelerate the release of high concentrations of polybrominated diphenyl ethers (PBDEs), and this situation causes environmental pollution and human health risks. The recycling technology of waste electronic plastics based on solvent processes can reduce environmental pollution and health risks from PBDEs. In this study, high impact polystyrene (HIPS) from waste TV sets was taken as the research object, and d-limonene and n-propanol were used as solvent and precipitant, respectively. We studied the relationship between the precipitation conditions and the size of precipitate particles, and the effect laws of precipitation conditions on the removal percentage of PBDEs were discussed. Transferring behavior of PBDEs during precipitation was investigated, and the parameters suitable for removing PBDEs from HIPS solution were confirmed. Results showed that lower HIPS concentration in d-limonene, lower precipitation temperature, higher mass ratio of n-propanol to HIPS solution, and greater stirring speed were conducive to form smaller and more uniform precipitate particles. All conditions (concentration, temperature, mass ratio, and stirring rate) that could increase the solubility of PBDEs in the mixed solvent of limonene and n-propanol or decrease the swelling degree of HIPS precipitate particles, or reduce the size of particles could improve the removal percentage of PBDEs. The investigated results indicated that insoluble PBDEs (e.g., decabromodiphenyl ether) transferred into the HIPS precipitate mainly through the generated crystals and then precipitated together with the HIPS particles, and soluble PBDEs (e.g., octabromodiphenyl ether) migrated into the precipitate by the solution entrained. The precipitate particles, which measured approximately 1.0 mm (on average), were obtained when the solution containing 10% of HIPS from waste TV shell was precipitated by adding n-propanol equivalent to twice the mass of the solution at 40 °C and 3000 r/min stirring speed. The total concentration of PBDEs in the precipitate particles (dried) was reduced to 2369 mg/kg, and 88.06% of the PBDEs in the original plastic solution was successfully removed by this process.

Measuring treatment costs of typical waste electrical and electronic equipment: A pre-research for Chinese policy making.

Waste Electrical and Electronic Equipment (WEEE) volume is increasing, worldwide. In 2011, the Chinese government issued new regulations on WEEE recycling and disposal, establishing a WEEE treatment subsidy funded by a levy on producers of electrical and electronic equipment. In order to evaluate WEEE recycling treatment costs and revenue possibilities under the new regulations, and to propose suggestions for cost-effective WEEE management, a comprehensive revenue-expenditure model (REM), were established for this study, including 7 types of costs, 4 types of fees, and one type of revenue. Since TV sets dominated the volume of WEEE treated from 2013 to 2014, with a contribution rate of 87.3%, TV sets were taken as a representative case. Results showed that the treatment cost varied from 46.4RMB/unit to 82.5RMB/unit, with a treatment quantity of 130,000 units to 1,200,000 units per year in China. Collection cost accounted for the largest portion (about 70.0%), while taxes and fees (about 11.0 %) and labor cost (about 7.0 %) contributed less. The average costs for disposal, sales, and taxes had no influence on treatment quantity (TQ). TQ might have an adverse effect on average labor and management costs; while average collection and purchase fees, and financing costs, would vary with purchase price, and the average sales fees and taxes would vary with the sales of dismantled materials and other recycled products. Recycling enterprises could reduce their costs by setting up online and offline collection platforms, cooperating with individual collectors, creating door-to-door collection channels, improving production efficiency and reducing administrative expenditures. The government could provide economic incentives-such as subsidies, low-cost loans, tax cuts and credits-and could also raise public awareness of waste management and environmental protection, in order to capture some of the WEEE currently discarded into the general waste stream. Foreign companies with advanced WEEE utilization technology could invest or participate in this area, producing profits for themselves while helping to develop and implement environmentally friendly and energy-saving technologies applicable to the Chinese market.

The use of air separation in recycling CRT TV sets.

The aim of this paper is to examine the possibility of use of air separation in recycling CRT TV sets and determine the effect of operating variables of separators. Eight CRT TV sets were collected and after manual disassembly, parts of CRT TV sets were sorted into four fractions taking into account their properties. The subject of this research was the fraction consisting of yokes of a cathode tube, cables, connectors and wires. Testing samples were obtained by manual disassembly, shredding and sieving, after which the separation on the model of a cross-flow gravity air separator with horizontal flow was carried out. Four grain sizes, 4/2mm, 2/1mm, 1/0.5mm and -0.5mm, were tested on the separator. Testing was carried out according to the central composite design for three factors: splitter height, air velocity and feed position. The evaluation of results was carried out by the analysis of two parameters: concentrate grade and recovery. The obtained values of the concentrate grade varied from 45.9% for the smallest grain size of -0.5mm to 89.4% for the grain size of 1/0.5mm while recovery was very high, mostly over 99%. The highest increase of metal content in the concentrate of 21.1% was recorded for the smallest grain size of -0.5%. The Analysis of Variance showed that the splitter height and feed position have the strongest effect on the concentrate grade.