Atsushi Terazono

Toxic metals in WEEE: characterization and substance flow analysis in waste treatment processes.

Waste electrical and electronic equipment (WEEE) has received extensive attention as a secondary source of metals. Because WEEE also contains toxic substances such as heavy metals, appropriate management of these substances is important in the recycling and treatment of WEEE. As a basis for discussion toward better management of WEEE, this study characterizes various types of WEEE in terms of toxic metal contents. The fate of various metals contained in WEEE, including toxic metals, was also investigated in actual waste treatment processes. Cathode-ray tube televisions showed the highest concentration and the largest total amount of toxic metals such as Ba, Pb, and Sb, so appropriate recycling and disposal of these televisions would greatly contribute to better management of toxic metals in WEEE. A future challenge is the management of toxic metals in mid-sized items such as audio/visual and ICT equipment because even though the concentrations were not high in these items, the total amount of toxic metals contained in them is not negligible. In the case of Japan, such mid-sized WEEE items as well as small electronic items are subject to municipal solid waste treatment. A case study showed that a landfill was the main destination of toxic metals contained in those items in the current treatment systems. The case study also showed that changes in the flows of toxic metals will occur when treatment processes are modified to emphasize resource recovery. Because the flow changes might lead to an increase in the amount of toxic metals released to the environment, the flows of toxic metals and the materials targeted for resource recovery should be considered simultaneously.

Fate of metals contained in waste electrical and electronic equipment in a municipal waste treatment process

In Japan, waste electrical and electronic equipment (WEEE) that is not covered by the recycling laws are treated as municipal solid waste. A part of common metals are recovered during the treatment; however, other metals are rarely recovered and their destinations are not clear. This study investigated the distribution ratios and substance flows of 55 metals contained in WEEE during municipal waste treatment using shredding and separation techniques at a Japanese municipal waste treatment plant. The results revealed that more than half of Cu and most of Al contained in WEEE end up in landfills or dissipate under the current municipal waste treatment system. Among the other metals contained in WEEE, at least 70% of the mass was distributed to the small-grain fraction through the shredding and separation and is to be landfilled. Most kinds of metals were concentrated several fold in the small-grain fraction through the process and therefore the small-grain fraction may be a next target for recovery of metals in terms of both metal content and amount. Separate collection and pre-sorting of small digital products can work as effective way for reducing precious metals and less common metals to be landfilled to some extent; however, much of the total masses of those metals would still end up in landfills and it is also important to consider how to recover and utilize metals contained in other WEEE such as audio/video equipment.

Estimation of energy recovery and reduction of CO2 emissions in municipal solid waste power generation

Using the heat from waste incineration to generate electricity requires the addition of generating equipment, while the manufacture, construction, and operation of this equipment also uses energy. And owing to the problem of superheater tube corrosion caused by the hydrogen chloride and other substances formed in conjunction with waste combustion, municipal solid waste (MSW) power generation cannot raise steam temperature very much, and generating efficiency is said to be low, at between 10 and 15%. However, we have found that, in terms of life cycle energy balance, MSW generation is about the same as currently operating commercial power plants. We also examined life cycle energy balance in relation to repowering, which is meant to increase MSW generating efficiency, and reburning, which is aimed at limiting both NOx and dioxin emissions. We found that these are effective methods for energy recovery, and that the gas turbines combined with waste incinerators for repowering have an optimum size that will improve overall efficiency.

Estimating the amount of WEEE generated in South Korea by using the population balance model

We estimated the amount of waste electrical and electronic equipment (WEEE) generated in South Korea by using the population balance model (PBM) based on a lifespan distribution analysis. This is the first study to apply PBM to estimate WEEE generation in South Korea. The lifespan distribution analysis of electrical and electronic equipment (EEE) was based on the results of a questionnaire survey of 1000 households, which were analyzed with the Weibull distribution. As a result, we could estimate the domestic service lifespan and lifespan distribution shape parameter for eight selected products. Using the lifespan distribution analysis and other data, such as the shipment volume and the number of products owned by households, we estimated the amount of WEEE generated for the eight selected items from 2000 to 2020. We found that 1.2 million air conditioners, 2.5 million televisions, 1.3 million microwave ovens, 1.2 million kimchi refrigerators, 17.0 million mobile phones, 1.7 million refrigerators, 2.0 million vacuum cleaners, and 1.4 million washing machines were generated as WEEE in 2010. We also compared our WEEE estimates with the number of items collected through the official WEEE recycling program from 2003 to 2009 and found that in 2009 washing machines had the highest collection rate (28%) and air conditioners had the lowest rate (7%).

Reuse of secondhand TVs exported from Japan to the Philippines

The trade of secondhand electrical and electronic equipment (EEE) from developed to developing countries has become a growing environmental issue owing to concerns about improper recycling of these goods in developing countries. We followed a 12-m cargo container of cathode-ray-tube color TVs exported from Japan to the Philippines in February 2008. We surveyed the number of TVs damaged in transport, as well as the number of malfunctioning TVs from this shipment. In addition, we present the results of interviews with 113 Filipino consumers who intended to buy secondhand EEE at nine secondhand shops in Metro Manila. Approximately 3% of the imported TVs were damaged upon arrival. The importer sold some of the units directly to local dealers, and kept the rest to repair, refurbish and resell. Approximately 40% of the imported TVs malfunctioned and needed repair in addition to basic reconditioning. Most interviewees indicated that they prefer to buy secondhand EEE because the prices are lower than those of brand-new products. Consumers indicated that they planned on using the product for an average of about 5years, but the actual period of use may be lower. Most end-of-life EEE in the Philippines is dismantled and recycled by unregulated companies and untrained individuals in markets or near landfill sites, and it is clear that a proper collection system and treatment methods are needed for e-waste. In addition to the material flow of secondhand TVs, we also discuss several economic aspects and appropriate control measures of the international reuse of secondhand TVs.

A Simplified Model for Spatially Differentiated Impact Assessment of Air Emissions

We developed a simplified emission dispersion and exposure-assessment model designed to reflect the site-specific health impacts of air pollution in life-cycle impact assessment (LCIA). We proposed an EXposure Per Emission Coefficient (EXPEC), a dimensionless parameter representing the relative amount of pollutant inhaled per emission. EXPEC values were calculated for two typical source categories - electric power plants and road vehicles — on a concentric circle model. The EXPEC values were significantly different for different locations and source categories. We examined the application of EXPEC in a case study that compared the effects of emissions from electric and gasoline-engine vehicles. EXPEC is a useful tool for assessing spatially differentiated potential impacts.

Battery collection in municipal waste management in Japan: challenges for hazardous substance control and safety

To clarify current collection rules of waste batteries in municipal waste management in Japan and to examine future challenges for hazardous substance control and safety, we reviewed collection rules of waste batteries in the Tokyo Metropolitan Area. We also conducted a field survey of waste batteries collected at various battery and small waste electric and electronic equipment (WEEE) collection sites in Tokyo. The different types of batteries are not collected in a uniform way in the Tokyo area, so consumers need to pay attention to the specific collection rules for each type of battery in each municipality. In areas where small WEEE recycling schemes are being operated after the enforcement of the Act on Promotion of Recycling of Small Waste Electrical and Electronic Equipment in Japan in 2013, consumers may be confused about the need for separating batteries from small WEEE (especially mobile phones). Our field survey of collected waste batteries indicated that 6-10% of zinc carbon and alkaline batteries discarded in Japan currently could be regarded as containing mercury. More than 26% of zinc carbon dry batteries currently being discarded may have a lead content above the labelling threshold of the EU Batteries Directive (2006/66/EC). In terms of safety, despite announcements by producers and municipalities about using insulation (tape) on waste batteries to prevent fires, only 2.0% of discarded cylindrical dry batteries were insulated. Our field study of small WEEE showed that batteries made up an average of 4.6% of the total collected small WEEE on a weight basis. Exchangeable batteries were used in almost all of mobile phones, digital cameras, radios, and remote controls, but the removal rate was as low as 22% for mobile phones. Given the safety issues and the rapid changes occurring with mobile phones or other types of small WEEE, discussion is needed among stakeholders to determine how to safely collect and recycle WEEE and waste batteries.

Development of a testing method for asbestos fibers in treated materials of asbestos containing wastes by transmission electron microscopy.

Appropriate treatment of asbestos-containing wastes is a significant problem. In Japan, the inertization of asbestos-containing wastes based on new treatment processes approved by the Minister of the Environment is promoted. A highly sensitive method for testing asbestos fibers in inertized materials is required so that these processes can be approved. We developed a method in which fibers from milled treated materials are extracted in water by shaking, and are counted and identified by transmission electron microscopy. Evaluation of this method by using asbestos standards and simulated slag samples confirmed that the quantitation limits are a few million fibers per gram and a few μg/g in a sample of 50mg per filter. We used this method to assay asbestos fibers in slag samples produced by high-temperature melting of asbestos-containing wastes. Fiber concentrations were below the quantitation limit in all samples, and total fiber concentrations were determined as 47-170×10(-6) f/g. Because the evaluation of treated materials by TEM is difficult owing to the limited amount of sample observable, this testing method should be used in conjunction with bulk analytical methods for sure evaluation of treated materials.

Estimation of secondhand personal computer import and export in Asian region

The purpose of this paper is to estimate export of used PCs by trade statistics and compared the results with other methods. The number of exported secondhand PCs can be estimated from export data from ports and quantity and price data to distinguish between shipments of new and used PCs. Exports of secondhand desktop and laptop PCs in 2001 were estimated to be 90,000 units and 245,000 units, and that of in 2004 were 649,000 units and 277,000 units, respectively. The number of PCs collected by manufacturers and exported abroad from Japan was compared with the situation in South Korea.

Effect of lead speciation on its oral bioaccessibility in surface dust and soil of electronic-wastes recycling sites

We measured bioaccessible lead (Pb) in simulated gastrointestinal fluids containing Pb-contaminated soil or dust from electronic waste (e-waste) recycling sites to assess the risk of Pb ingestion. The physiologically based extraction test (PBET) was used as in vitro bioaccessibility assay. Pb speciation was determined using X-ray absorption spectroscopy. The total Pb concentrations in dusts (n=8) and soils (n=4) were in the range of 1630-131,000 and 239-7800mg/kg, respectively. Metallic Pb, a common component of e-waste, was ubiquitous in the samples. We also found Pb adsorbed onto goethite and as oxides and carbonate, implying soil mixing and weathering influences. Pb phosphate and organic species were only found in the soil samples, suggesting that formation was soil-specific. We identified other Pb compounds in several samples, including Pb silicate, Pb chromate, and Pb(II) hydrogen phosphate. A correlation analysis indicated that metallic Pb decreased bioaccessibility in the stomach, while a Pb speciation analysis revealed a low bioaccessibility for Pb phosphates and high bioaccessibility for organic Pb species. The health risk based on bioaccessible Pb was estimated to be much lower than that of total Pb due to the lower concentrations.