Identification of estrogenic compounds emitted from the combustion of computer printed circuit boards in electronic waste

Rapid changes in technology have brought about a surge in demand for electronic equipment. Many of these products contain brominated flame-retardants (BFRs) as additives to decrease the rate of combustion, raising concerns about their toxicological risk. In our study, emissions from the combustion of computer-printed circuit boards were evaluated in the T47D-KBluc estrogen-responsive cell line at a series of concentrations. There was significant activity from the emission extract when compared to the positive control, 0.1 nM estradiol. After HPLC fractionation, GC/MS identified ten chemicals which included bisphenol A; the brominated derivates mono-, di-, and tribisphenol, triphenyl phosphate, triphenyl phosphine oxide, 4'-bromo-[1,1'-biphenyl]-4-ol,3,5-dibromo-4-hydroxybiphenyl,3,5-dibromo-2-hydroxybiphenyl, and the oxygenated polyaromatic hydrocarbon benzanthrone. Commercially available samples of these ten compounds were tested. The compound 4'-bromo-[1,1'-biphenyl]-4-ol resulted in dose-dependent significant increases for luciferase activity at concentrations ranging from 0.1 to 10 microM in the T47D-KBluc assay. The chemical also demonstrated an affinity for binding to the estrogen receptor (ER) with an IC50 of 2 x 10(-7) M. To determine the uterotrophic activity, three doses (50, 100, and 200 mg/kg/day) of 4'-bromo-[1,1'-biphenyl]-4-ol were administered to adult ovariectomized Long-Evans rats for 3 days. Treatment of the animals with 200 mg/ kg/day showed an increase in uterine weight Hence one new chemical, released by burning of electrical wastes, was identified which displays estrogenic activity both in vitro and in vivo. However, it was about 1000-fold less potent than ethynyl estradiol.     

Recycle technology for recovering resources and products from waste printed circuit boards

The printed circuit board (PCB) contains nearly 28% metals that are abundant non-ferrous metals such as Cu, Al, Sn, etc. The purity of precious metals in PCBs is more than 10 times higher than that of rich-content minerals. Therefore, recycling of PCBs is an important subject not only from the treatment of waste but also from the recovery of valuable materials. Chemical and mechanical methods are two traditional recycling processes for waste PCBs. However, the prospect of chemical methods will be limited since the emission of toxic liquid or gas brings secondary pollution to the environment during the process. Mechanical processes, such as shape separation, jigging, density-based separation, and electrostatic separation have been widely utilized in the recycling industry. But, recycling of waste PCBs is only beginning. In this study, a total of 400 kg of waste PCBs was processed by a recycle technology without negative impact to the environment. The technology contained mechanical two-step crushing, corona electrostatic separating, and recovery. The results indicated that (i) two-step crushing was an effect process to strip metals from base plates completely; (ii) the size of particles between 0.6 and 1.2 mm was suitable for corona electrostatic separating during industrial application; and (iii) the nonmetal of waste PCBs attained 80% weight of a kind of nonmetallic plate that expanded the applying prospect of waste nonmetallic materials.     

A plate produced by nonmetallic materials of pulverized waste printed circuit boards

Noble metals and Cu mainly are recycled in treating waste printed circuit boards (PCBs), and a large amount of nonmetallic materials in PCBs are disposed of by combustion or landfill, which may cause secondary pollution and resource-wasting. In this study, a kind of nonmetallic plate (NMP) has been produced by nonmetallic materials of pulverized waste PCBs. The NMP is produced by a self-made hot-press former through adding resin paste as a bonding agent. Furthermore, microshapes of nonmetallic materials and effects of the contents and particle sizes of nonmetallic materials on mechanical properties of the NMP are investigated. It has been found that the nonmetallic materials with particle size from 0.3 to 0.15 mm are in the form of fiber bundles, with the majority of fibers being encapsulated in resin. Nonmetallic materials shorter than 0.07 mm consist of single glass fiber and resin powder. When nonmetallic materials content was 20 wt%,the NMP with particle size of nonmetallic materials less than 0.07 mm, has excellent mechanical properties,which results in a flexural strength of 68.8 MPa and a Charpy impact strength of 6.4 kJ/m2. This novel technique offers a possibility for recycling of nonmetallic materials of PCBs and resolving the environmental pollutions during recycling of PCBs.     

Separating and recovering Pb from copper-rich particles of crushed waste printed circuit boards by evaporation and condensation

Waste printed circuit boards (WPCBs) are treated by crushing and electrostatic separation to obtain the copper-rich particles. However, the copper-rich particles contain a certain content of solder, which may cause Pb contamination if improperly treated. The separation behaviors of Pb from single solder and solder mixed with Cu particles under vacuum are studied in this work. Due to the presence of Cu particles in the copper-rich particles, it becomes much easier to separate Pb from mixed particles than from single solder. On the basis of the experiments, the rules and phenomena different from previous studies are concluded, including the multilayer evaporation effect, the formation of Cu-Sn intermetallic compound and so on. Mechanisms of these phenomena are also explored. Pb is separated and recovered from copper-rich particles of crushed WPCBs at 1123 K for 90 min under 0.1-1 Pa. The metals including Cu, Pb, Sn in WPCBs are all efficiently recovered. This work enriches separating rules for recovering Pb by evaporation and condensation, and also points out an efficient and promising method for recovering toxic heavy metals from WPCBs.     

Isotopic tracing of landfill leachates and pollutant lead mobility in soil and groundwater

Here we provide evidence of the capability of stable lead isotopes to trace landfill leachate in a shallow groundwater. The municipal landfill we have investigated is located in southeastern France. It has no bottom liner, and wastes are placed directly on the ground. Stable lead isotopes allow the characterization of this landfill leachate signature (206Pb/207Pb = 1.189 +/- 0.004) that is clearly different from that of the local atmosphere (206Pb/207Pb = 1.150 +/- 0.006) and crustal lead (206Pb/207Pb = 1.200 +/- 0.005). Piezometers located in the direct vicinity of the landfill generally display this contaminant imprint. The landfill plume is monitored up to 1000 m downgradient of the landfill, in very good agreement with evaluation from chloride concentration. Meanwhile, 206Pb/207Pb ratios measured at a piezometer located 4600 m downgradient of the landfill suggest a contamination by the landfill plume. This result shows that the complexity of a pollutant plume dispersion in this shallow groundwater system requires several independent tracers to clearly resolve origin and transport pathways for contaminants. Furthermore, seasonal rainfall variation for this Mediterranean mixed Quaternary alluvion reservoir and the use of KCl fertilizers might favor an efficient remobilization of atmospheric lead in plowed soils and its transfer into groundwater as shown by lead isotope systematics.     

Release of hydrogen chloride from combustibles in municipal solid waste

Study of the inorganic chlorides in municipal solid waste (MSW) shows that the main source of inorganic chlorides in MSW is food. The main organic source of HCl emission from MSW is plastic. But wood, textiles, and food also produce a large amount of HCl when they are combusted. Each combustible shows a different HCl releasing temperature range. At 973 K, there are 30-70% of the total chlorine left in the char of each combustibles in MSW.     

Pollutant formation and emissions from cement kiln stack using a solid recovered fuel from municipal solid waste

The thermal decomposition of a solid recovered fuel (SRF) has been studied by two techniques. First, laboratory-scale experiments were performed in a horizontal furnace in which different atmospheres were studied to analyze the dioxins and furans (PCDD/Fs) evolved from the decomposition of the material. Sulfur presence was revealed to be important in PCDD/Fs formation. In the second technique, the emissions of various pollutants (PAHs, PCDD/Fs, metals, acid gases, etc.) were determined in a cement kiln fed on different proportions of SRF material, and where a maximum feed rate of 15000 kg SRF/h was achieved. In the laboratory furnace the dioxin toxicity revealed a maximum when the amount of oxygen in the atmosphere increased until approximately stoichiometric conditions. In the cement kiln, all emitted pollutants were under the legal limits. No correlation between SRF input and metal emission was observed.     

Innovated application of mechanical activation to separate lead from scrap cathode ray tube funnel glass

The disposal of scrap cathode ray tube (CRT) funnel glass has become a global environmental problem due to the rapid shrinkage of new CRT monitor demand, which greatly reduces the reuse for remanufacturing. To detoxificate CRT funnel glass by lead recovery with traditional metallurgical methods, mechanical activation by ball milling was introduced to pretreat the funnel glass. As a result, substantial physicochemical changes have been observed after mechanical activation including chemical breakage and defects formation in glass inner structure. These changes contribute to the easy dissolution of the activated sample in solution. High yield of 92.5% of lead from activated CRT funnel glass by diluted nitric acid leaching and successful formation of lead sulfide by sulfur sulfidization in water have also been achieved. All the results indicate that the application of mechanical activation on recovering lead from CRT funnel glass is efficient and promising, which is also probably appropriate to detoxificate any other kind of leaded glass.     

Cost effectiveness of reducing dioxin emissions from municipal solid waste incinerators in Japan

The main sources of dioxin emissions are municipal solid waste incinerators. The Japanese national government has set an emission standard for dioxins to reduce dioxin exposure levels. In this study, cost-effectiveness analyses are carried out regarding countermeasures that were recently taken and are being taken at municipal solid waste incinerators in Japan. Annual costs were estimated by telephone survey and model calculations. Annual decrease in the incidence of cancer was estimated in three steps. First, the annual decrease in the volume of dioxin emissions was estimated. Next, using a mathematical model, the annual decrease in human exposure was estimated. Finally, the annual decrease in the incidence of cancer was estimated by applying the cancer slope factor. When annual costs are divided by the annual number of life-years saved, cost per life-year saved (CPLYS) was obtained. CPLYS was estimated to be 7.9 million yen for emergency countermeasures and 150 million yen for long-term countermeasures. However, it must be noted that these obtained CPLYSs are highly dependent on the cancer slope factor and should be considered as an upper limit since there may be a cancer effect threshold.     

Lead isotopic composition of fly ash and flue gas residues from municipal solid waste combustors in France: implications for atmospheric lead source tracing

Fly ash and flue gas residues from eight municipal solid waste combustors (MSWC) in France (1992--93 and 1998/ 2002) were analyzed for their Pb isotopic composition. Fly ashes are more representative of solid residual particles, whereas flue gas residues reflect mostly the composition of gas phases. Both sample types contain hundreds to thousands of micrograms of metals per gram. Leaching experiments showed that metals are present in condensed phases, probably as sulfates and chlorides, and suggest that Cd, Pb, and Zn are highly fractionated from one another during volatilization/condensation processes occurring during combustion. Although all the samples analyzed define a fairly restricted range in Pb isotopic compositions (206Pb/207Pb = 1.148-1.158 and 208Pb/206Pb = 2.101-2.114) compared to other environmental samples, some MSWC produce materials having distinct isotopic compositions, whereas others display very similar ones. Isotopic heterogeneity is also measured between samples from a single MSWC. This is interpreted as resulting from the heterogeneity of the waste source materials. The range of Pb isotopic composition of incinerator materials form a well-defined linear array in the 208Pb/206Pb versus 206Pb/207Pb diagram. This array is compatible with the previously reported European standard pollution (ESP) line and most probably represent the average lead isotopic composition of industrial atmospheric emissions in France, with the following ratios: 206Pb/207Pb = 1.154+/-0.003 and 208Pb/206Pb = 2.107+/-0.003 (1sigma).     

Removal of estrogenic activity from municipal waste landfill leachate assessed with a bioassay based on reporter gene expression

The leachate of a municipal waste landfill was tested for estrogenic activity using a reporter-gene-based bioassay with a human breast-cancer-derived cell line (MVLN cells). The leachate was processed with two different membrane-employing processes operating in parallel. One process consists of aerobic biological degradation, ultrafiltration, and subsequent adsorption to activated carbon. The second process was a reverse osmosis treatment of the raw leachate. Both processes are common in the treatment of landfill leachate. Here, the efficacy of the two processes to remove "estrogenicity" was compared. Both treatment processes removed more than 97% of the estrogenic activity, calculated as estradiol equivalents (EEQs), but they were not equally effective. After adsorption to activated carbon, no estrogenicity was detected, whereas concentrated effluent of the reverse osmosis treatment still elicited an estrogenic response in the bioassay. On the basis of chemical analysis, it is proposed that bisphenol A was responsible for the majority of estrogenic activity in the raw and treated leachate. Although the contribution of treated leachate to the estrogenic load on the aquatic environment seems to be low compared to that of sewage treatment works, the high estrogenic activity in raw landfill leachate stresses the necessity for the appropriate treatment of these leachates.     

固废填埋厂对环境的影响及治理措施探析

本文从固废的概念出发,结合固废污染现状和目前国内垃圾填埋厂的现状分析,对垃圾分类、全过程全寿命管理、加强填埋场运行管理和污染控制、做好填埋的绿化覆盖等治理措施进行了初步探析,希望对相关的工作者有所帮助。     

Inhibition of polybrominated dibenzo-p-dioxin and dibenzofuran formation from the pyrolysis of printed circuit boards

Waste printed circuit boards containing brominated flame retardants were pyrolyzed in a high-temperature melting system to observe the formation behaviors of polybrominated dibenzo-p-dioxins (PBDDs) and dibenzofurans (PBDFs). In this study, the results showed that the formation of PBDD/ Fs during pyrolysis can be destroyed under controlled primary combustion conditions. There were two significant factors that influenced the extent of PBDD/F formation. The first factor was temperature. The results showed that, both the total PBDD/F content in the bottom ash and the total PBDD/F emission factor from the flue gas decrease by approximately 50% with an increase of the pyrolysis temperature from 850 to 1200 degrees C. The second factor was the addition of CaO. The possible mechanism involves the reaction between CaO and HBr to form the solid-phase product CaBr2. Thus, the addition of CaO is effective in adsorbing HBr and results in the inhibition of PBDD/F synthesis by more than 90% and further prevents the acid gases (HCl and HBr) that corrode the equipment. In conclusion, due to the persistence and toxicity of PBDD/Fs, a combined regulation for controlling both PCDD/Fs and PBDD/Fs is of great importance for environmental protection issues.     

Application of electron beam for the reduction of PCDD/F emission from municipal solid waste incinerators

The electron-beam technology was applied to reduce the emission of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in a flue gas of 1000 m(3)N/h from the municipal solid waste incinerator (MSWI) at a temperature of 200 degrees C. More than 90% decomposition of PCDD/Fs was obtained using an electron accelerator at a dose of 14 kGy. The decomposition was initiated through reactions with OH radicals produced by the irradiation of flue gases, followed by oxidation such as the ring cleavage of the aromatic ring, the dissociation of ether bond, and dechlorination. The cost analysis estimated that the electron-beam system can cut the annualized cost by approximately 50% for the treatment of PCDD/Fs in a pre-dusted MSWI flue gas as compared with a bag-filter system when operating on electricity generated from an incineration. Electron-beam technology is an economically and technologically useful method for reducing PCDD/Fs in an incineration flue gas.     

Formation and durability of dithiocarbamic metals in stabilized air pollution control residue from municipal solid waste incineration and melting processes

In Japan, chemical stabilization of metals using a chelating agent composed of dithiocarbamic salt is the prevailing technique for the final disposal of air pollution control (APC) residue from municipal solid waste (MSW) incineration and melting processes. The objective of this study is to quantitatively evaluate the formation and durability of dithiocarbamic metals (DCM) in treated APC residue. In this research, sodium N,N--diethyldithiocarbamate trihydrate was used as a chelating agent. An extraction method using n-butyl acetate was developed to separate DCM from residue. This method elucidated the competitive formation of DCM among Cu, Pb, Cd, and Zn. The metal fraction forming DCM was about 70 and 90% of the total content of Pb in APC residue from incineration and melting, respectively. Regarding durability in the environment, 240 day curing of the chelate-treated APC residue showed that air-contact conditions induced degradation of DCM with time. On the other hand, sealed conditions did not bring about a decrease over the course of the experiment. These results imply that DCM degradation proceeds when the treated residue comes into contact with air in actual landfills.