Jing Wei Wang

Life Cycle Analysis on Regenerating and Energy Recovery of Plastic Solid Waste Management in Shanghai

Over the past several decades with significant technological advances there has been continuous increase in plastic manufacturing in China, which has contributed to the production of a great deal of plastics worldwide every year, and at the same time it has resulted in a large amount of plastic solid waste (PSW). It has great potential values for waste plastics to reuse as secondary materials, which may lessen pressure on resource and environment. The paper studies the status of waste plastics in recycling, reusing and reducing on management countering on the increase in the flow of waste plastics in Shanghai. In light of the methodology of life cycle, the study analyzes the environmental impacts associating with the alternatives in a ‘cradle to grave’ approve to PSW technological recycling systems. We will choose regenerating and energy recovery processes based on site investigation and literatures data in Shanghai to analyze recycling options and how various processes affect the environment. Life-cycle methodology was very suitable for evaluating the overall environmental consequences, and could be used for making decisions and planning strategies with the rapid increase of plastic solid waste generation for Shanghai.

A Life-Cycle Based Approach to the Remanufacturing Printing Supplies in Shanghai

With the fast growing of printing supplies industry in Shanghai, it creates a large waste stream of obsolete printing supplies and causes great pressure on the environment. The information of remanufacturing printing supplies in Shanghai is gathered and waste stream is analyzed. As a case study of original toner cartridge and remanufacturing toner cartridge is compared in the context of life cycle methodology. The results show raw materials, energy consumption and pollution emission of the remanufactured toner cartridge are less than these of original toner cartridge. Environmental loads equitant including global warming potential, acidification potential, photo-oxidant formation potential, solid waste and fume from remanufacturing toner cartridge are cut 3.61%, 3.84%, 15.24% and 22.52% comparing to original toner cartridge. Its significance is that remanufacturing printing supplies can be more profitable and less harmful to the external environment than conventional manufacturing process. It also discusses strategies for lowering the environmental burden to promote the remanufacturing printing supplies in Shanghai.

Environmental Risk and Recoverable Potential Evaluation of Heavy Metals in the Sludge from the Industrial Wastewater in China

During the treatment of wastewater from metal production and processing industries, a huge volume of sludge is generated. Sludge from the industrial effluent is usually abandoned or used in agriculture as fertilizer due to the presence of phosphorus, potassium and other inorganic elements, or landfilled. In our work, metals concentration in the sludge from different industries of multi-area, China, was determined and the recoverable potential was assessed. It indicated that the sludge from electroplating, PCB, leather treatment, metal smelter and stainless steel industries was restricted its use as a fertilizer because that the sludge had too high concentration of toxic heavy metals. Meanwhile, it was seen that Ag, Cu, Co, Ni, Pb, Zn contents in the sludge from some industries had exceeded the minimum standards of industrial smelting and had the value recycled. It is imperative and beneficial to find a low-cost, environmentally friendly recycling technology to recover the metals in sludge from industrial wastewater.

Pyrolysis Behavior and Kinetics of Polyurethane Insulation Materials from Waste Refrigerators

Pyrolysis characteristics and kinetics of polyurethane insulation materials from waste refrigerators were investigated using TG-FTIR technique under N2 atmosphere. Results showed that the whole thermal process could be divided into three stages and the main pyrolysis occurred in 260-600°C. The distribution activation energy model (DAEM) was applied to analyze the pyrolysis kinetics. The estimated activation energies ranged from 122.8 to 188 kJ/mol and the pre-exponential factors k0 varied from 108 to 1013 s-1. The composition of evolved gas included CFC-11, CO2, CH4, CO, NH3, HCN and some organic compounds, the evolution characteristics of main gas products had also been discussed.

Life Cycle Assessment of the Bio-Hydrometallurgical Process of Recycling Copper from Printed Circuit Boards Scraps

Recently, a few studies have been undertaken for the extracting of metallic copper from electronic scrap/printed circuit boards by bioleaching - solvent extraction-electrowinning. Results of the present investigation indicate that bioleaching-solvent extraction-electrowinning could be a new cleaner hydrometallurgy route for recovery copper from the PCBs.The life cycle assessment method was used to investigate the environmental impacts of the new biohydrometallurgical process of production of metallic copper. The energy consumption，greenhouse effect，acidification in the new processes is studied and compared. The results indicate that the environmental impacts of bioleaching - solvent extraction-electrowinning technology is less than the conventional mechanical-pyrometallurgical processes and pyrometallurgical processes.

Investigation on Dissolution of Brominated Epoxy Resin Using Ionic Liquid [Bmim]Cl from Waste Printed Circuit Boards

Treatment technology of brominated epoxy resin (BER) is still a big challenge to waste printed circuit boards (PCBs) recycling. In order to make full use of the materials, ionic liquid 1-butyl-3-methyl imidazole chloride ([Bmim]Cl) was used to dissolve BER to separate glass fibers from PCB nonmetallic powders. The effects of dissolving parameters including temperature, time and solid/ liquid ratio on the dissolution rate of BER were investigated. The dissolved BER were regenerated and were characterized by FTIR and thermal analysis. Results showed that [Bmim]Cl was a good direct solvent for BER dissolution and at a suitable condition of 170°Cfor 6 hours with solid/liquid ratio of 1: 20 (g/g), nearly 90% of BER in original powders were dissolved. The possible dissolution mechanism was also discussed.

Extraction of Lead from Spent Leaded Glass in Alkaline Solution

This study evaluates the efficiency of lead (Pb) extraction from spent leaded glass in strongly alkaline solution after mechanical activation in a planetary ball mill as the chemical breakage and defects formed in the inner structures will contribute to the easy dissolution of the activated leaded glass. The influence of rotate speed and time of mechanical activation, NaOH concentrations, leaching temperature, phase ratios (v/w) had been studied. More than 78% of Pb extraction can be achieved after mechanical activation, compared with 3.5% Pb extraction for chemical leaching of non-activated samples. High purity lead powder can be obtained by electrowinning from the leaching solution. The Pb-depleted solution can be recycled into the leaching step. Thus, a novel hydrometallurgical process for recovering Pb from spent leaded glass in alkaline solution is proposed.

Dewatering Performance of Sewage Sludge during the Thermal Compression Process

Sewage sludge proves to be difficult to dewater due to its composition and biological nature, and it is unsuitable for disposal with high moisture content. In the present work, sewage sludge is dewatered by the thermal compression, which shows unique separation advantages of various materials, and the effects of applied temperature and pressure on the dewatering performance are investigated. The filtrate SCOD reveals that higher temperature benefits the disruption of sludge flocs, resulting in the release of organic content. According to the accumulative filtrate volume, higher temperature and pressure facilitate the dewatering process, obtaining sludge cake with lower moisture content.

Assessing the Life Cycle Environmental and Economic Performance of Copper Slag Recycling

Industrial solid waste refers to all solid waste derived from industrial processes. Industrial solid waste, on the one hand, may lead to environmental risk and safety issue; on the other hand, contains valuable recyclable resources. Taking copper slag as a case study, the life cycle environmental and economic performance of recycling process were analyzed by using life cycle assessment and life cycle costing approaches. The functional unit was defined as the recycling of 1 ton of copper slag. The results showed that the process of production of cement after floatation was the optimal scenario for copper slag recycling, and its life cycle impact and life cycle cost were-67.22 Pt and-479.28 yuan, respectively. Specifically, the dominant environmental impact category of copper recycling process was respiratory (inorganic). In addition, raw material, fuel and power, equipment depreciation and transportation contributed to the life cycle cost in descending order of their proportion.

A Study on Explosion Characteristics of Toner Powder

Toner powder is an important constituent of a toner cartridge for a laser printer and has potential hazards of combustion and explosion because of its physicochemical characteristics. In this paper, physicochemical, combustible and explosive characteristics of hpQ2612A toner are investigated experimentally. The mean size of the toner powder is about 2.45 μm and it has several organic groups such as carboxyl group, hydroxyl group and carbonyl group which make the toner dust much easier to combust. The TG-DSC curves show that the toner dust is combustible and the combustion process starts at about 368 . The dust explosion characteristics of the toner dust were, respectively: MIE=5~30 mJ, Pmax=0.74 MPa, (dP/dt)max=100.5 MPa/s, LEL=40~50 g/m3. These results reveal that the toner powder is a dangerous industry dust and has the possibility to make tragedy such as combustion or even explosion.