Economic evaluation of optional recycling processes for waste electronic home appliances

This paper presents an economic evaluation of three typical recycling processes for the five main types of waste electronic home appliances (EHA) (TV set, refrigerator, washing machine, air conditioner and personal computer) in Beijing, the capital of China. The main purpose is to identify the formal management framework with economic feasibility for the waste EHA generated in large municipalities of China. It is found that the advanced technologies, which have mechanical processing units, should be introduced to recover more valuable materials from the waste appliances. Net revenues with a range of 90–240 RMB (Chinese currency unit, 1.0 USD ≈ 8.0 RMB) per unit, depend on the type of appliance, could be expected in case of using the most complicated procedures which can separate both metals and plastics from the shredded mixtures. However, the recycling of waste refrigerator and waste washing machine will, respectively, spend about 100 and 6 RMB per unit if solely by simple manual dismantling. Revenues from recycling of the other three types of appliances are positive but quite low in this case. Although positive revenues could be achieved from the isolated evaluation of recycling, the entire management system, which also covers the phases of collection and transportation, is economically infeasible if the waste appliances are bought from the households still at current prices. Based on a survey of the householder's attitude to the cost for waste EHA management, which was conducted earlier, the practical way to construct a formal management system for waste EHA in Beijing is to reduce the citizen's traditional expectation to the values of waste appliances and encourage their transfer to the formal collection system at lower prices.     

Use and disposal of large home electronic appliances in Vietnam

In this study, e-waste flows of five large home appliances (color televisions, refrigerators, washing machines, personal computers, and air conditioners) in Vietnam are investigated. A social survey was performed to investigate the situation on using appliances in households as well as on the disposal of appliances by the first users. Future quantities of e-waste were estimated using a model that combines use of the Weibull distribution, the logistic function, and the population balance model. It was forecast that about 3.86 million appliances, or 114 000 tons, will be discarded in 2010, and about 17.2 million appliances, or 567 000 tons, in 2025, showing a rapid increase of e-waste in the near future.     

Seasonal and spatial variation of atmospheric 210Pb and 7Be deposition: features of the Japan Sea side of Japan

Monthly depositional fluxes of (210)Pb and (7)Be at Tatsunokuchi, Japan which faces the Japan Sea were studied over a 12-year period from 1991 to 2002. The data were compared with the spatial variability of these fluxes at Taejon in Korea and at 11 other sites in Japan from Ishigaki of the southern islands of Okinawa to Wakkanai of the northern end of Hokkaido over a 2-year period from 2000 to 2001. The monthly depositions of both (210)Pb and (7)Be at Tatsunokuchi revealed very similar seasonal variations with a single peak; both depositions were high in winter and low in summer. This phenomenon was found to be not transient but stationary. The deposition of these nuclides was much greater on the Japan Sea side of Japan than on the Pacific Ocean side. The cause for high deposition of (210)Pb and (7)Be in winter might be explained by a combination of a series of the following processes: blowing out of air masses with a high (210)Pb concentration near the surface layer over the continent by strong winter monsoons, additional flow of cold air masses with high (7)Be concentration at high latitude, well-mixing with generation of ascending current and convection clouds over the Japan Sea, and heavy snowfalls accompanying them.     

Evaluation of solubilizing ability of humic aggregate basing on the phase-separation model

Solubilizing abilities of aggregates of humic acid (HA) to chlorinated benzenes (CBs) were investigated by means of the apparent water solubility enhancement. Both the water solubilities of 1,4-dichlorobenzene (DCB) and 1,2,4,5-tetrachlorobenzene (TeCB) linearly increased with increasing concentration of HA above the critical micelle concentration (CMC). Such solubilization behavior of CBs for HA was compatible with those for sodium dodecyl sulfate (SDS). These results indicate that the solubilization of CBs in the aqueous solution of HA above the CMC can be interpreted on the basis of the phase-separation model. Thus, the partition coefficients (K(mic)) of CBs between water and HA aggregate phases were calculated by assuming this model. The fact that the K(mic) value increased with increasing K(ow) of CBs supported the partition into the HA aggregate phase by hydrophobic interaction. The estimated K(mic) values of DCB were not dependent on the solution pH. Both K(mic) values of DCB and TeCB for the HA aggregate were found to be 4-5-fold lower than those of SDS.     

The role of metals in dioxin formation from combustion of newspapers and polyvinyl chloride in an incinerator

Newspapers impregnated with NaCl mixed with various chloride metals (CuCl2, MgCl2, MnCl2, FeCl3, NiCl2, and CoCl2) and electric wire coated with polyvinyl chloride (PVC) were combusted in a well-controlled incinerator. Exhaust gas samples collected at the outlet of the incinerator were analyzed for dioxins (PCDDs, PCDFs, and coplanar PCBs) by gas chromatography/mass spectrometry. The amount of total dioxins formed from newspaper samples ranged from 34.2 ng/g (with NaCl+CoCl2) to 67.0 ng/g (with NaCl+CuCl2). PCDFs composed 88-94% of the total dioxins formed in the exhaust gases. The highest levels of PCDF isomers obtained were Cl3-CDF from the sample with NaCl+CuCl2 (14.8 ng/g), Cl2-CDF from the sample with NaCl+MgCl2 (12.3 ng/g), and Cl(1)-CDF from samples with NaCl+MnCl2 (12.6 ng/g), with NaCl+FeCl3 (11.8 ng/g), and with NaCl+NiCl2 (13.3 ng/g), and with NaCl+CoCl2 (8.62 ng/g). The total of Cl4-8-CDDs comprised 76-88% of the total Cl1-8-CDDs. In particular, Cl7-CDDs had the highest levels except for the sample with NaCl+NiCl2. Total dioxins formed from samples of electric wire coated with PVC and PVC alone were 38.3 ng/g and 112 ng/g, respectively, suggesting that the presence of copper reduced dioxin formation.     

Global pollution monitoring of polychlorinated dibenzo-p-dioxins (PCDDs), furans (PCDFs) and coplanar polychlorinated biphenyls (coplanar PCBs) using skipjack tuna as bioindicator

In order to elucidate the global distribution of dioxins and related compounds, such as PCDDs, PCDFs and coplanar PCBs, levels of these compounds were determined in the muscle of skipjack tuna (Katsuwonus pelamis) collected from the offshore waters and open seas near Japan, Taiwan, Philippines, Indonesia, Seychelles and Brazil, and the Japan Sea, the East China Sea, the South China Sea, the Indian Ocean and the North Pacific Ocean. PCDDs, PCDFs and coplanar PCBs were detected in almost all the specimens collected from all the locations surveyed, indicating widespread contamination by these compounds in the marine environment. Higher concentrations of dioxins and coplanar PCBs were detected in the samples from temperate Asian regions, plausibly due to larger usage and anthropogenic generation in highly industrialized countries around the East China Sea and the South China Sea, such as Japan, Korea, Taiwan, Hong Kong and coastal China.     

Adsorption and removal of oxo-anions of arsenic and selenium on the zirconium(IV) loaded polymer resin functionalized with diethylenetriamine-N,N,N',N'-polyacetic acid

A polymer adsorbent in which a Zr(IV)-edta complex analogue is immobilized has been prepared and applied to the removal of oxo-anions of As(III), As(V) and Se(IV). Effective retention of these anions has been demonstrated with the proposed polymer complex system. The adsorption mechanism of oxo-anions onto the Zr(IV)-chelated polymer complex has been investigated using Zr(IV)-edta as the model compound. The formation of mixed complexes with oxo-anions has been exemplified by the isolation of the carbonato complex K2[Zr(CO3)edta].3H2O, the structure of which has been confirmed by X-ray crystallography. NMR study suggests that oxo-anions that form weak or moderate conjugate acids, including those of As(III), As(V) and Se(IV), can form mixed complexes with Zr(IV)-edta using the unsaturated coordination site. However, oxo-anions of strong conjugate acids did not show any appreciable interaction with this complex. According to these observations, retention of oxo-anions on the Zr(IV)-chelated polymer complex has been interpreted by a ligand substitution reaction. The adsorption characteristics of As(III), As(V) and Se(IV) on the Zr(IV)-loaded resin have been examined with respect to the equilibrium adsorption, percentage extraction and the effect of co-existing ions. The adsorption and desorption cycles of the oxo-anions have been demonstrated using a column packed with the proposed resin without any loss of column performance, which indicates the possibility for repeated use.     

Novel malonate-type copolymers containing vinyl alcohol blocks as biodegradable segments and their builder performance in detergent formulations

Poly[(disodium methylene malonate)-co-(vinyl alcohol)] [P(DSMM-VA)] and poly[(disodium ethoxymethylene malonate)-co-(vinyl alcohol)] [P(DSEMM-VA)] containing a poly(vinyl alcohol) (PVA) block as a biodegradable segment were prepared and their biodegradability and functionality were evaluated and compared with those of the corresponding fumarate and maleate copolymers. It was found that the 1,1-dicarboxylate-type copolymers, P(DSMM-VA) and P(DSEMM-VA), showed better biodegradability than the corresponding 1,2-dicarboxylate-type copolymers, P(DSF-VA) and P(DSM-VA). This improved biodegradability of P(DSMM-VA) and P(DSEMM-VA) is probably attributable to their more expanded polymer chain in aqueous solution, which will be more accessible to the degrading enzymes. The minimum chain length of the PVA-block, which acts as a biodegradable segment in the polymer chain, is estimated to be 2–3 and 3–4 monomer units for P(DSMM-VA) and P(DSEMM-VA), respectively. On the other hand, the minimum PVA block is about 5 and 7 monomer units for the fumarate and maleate copolymers, respectively. It was confirmed that P(DSMM-VA) showed excellent builder performance compared to the corresponding fumarate copolymer.Paper presented at the Bio/Environmentally Degradable Polymer Society—Second National Meeting, August 19–21, 1993, Chicago, Illinois.