Qifei Huang

Polybrominated diphenyl ethers in soils, sediments, and human hair in a plastic waste recycling area: a neglected heavily polluted area.

The release of pollutants during the recycling of contaminated plastics is a problem which has drawn worldwide attention; however, little information on the transfer of polybrominated diphenyl ethers (PBDEs) in these processes is available. We conducted a survey of PBDEs in soils, sediments, and human hair in a typical plastic waste recycling area in northern China. The total concentrations (ng/g) of 21 PBDEs were 1.25-5504 (average 600), 18.2-9889 (average 1619), and 1.50-861 (average 112) in soils, sediments, and hair, respectively. The PBDE concentrations were comparable to concentrations observed in e-waste recycling areas; however, the concentrations in soils and sediments were 1-3 orders of magnitude higher than in other areas, and the concentrations in hair were much higher than in other areas. This indicates that this area is highly polluted with PBDEs. BDE-209 was the dominant congener (representing 91.23%, 92.3%, and 91.5% of the total PBDEs observed in soils, sediments, and hair, respectively), indicating that the commercial deca-BDE product was dominant. The commercial penta- and octa-BDE products made small contributions to the total PBDE concentrations, unlike what has been found in some e-waste recycling areas. Our results show that crude plastic waste processing is a major contributor of PBDEs to the environment and humans, which should be of great concern.

Organochlorine pesticides in the lower reaches of Yangtze River: Occurrence, ecological risk and temporal trends

Residues of 24 organochlorine pesticides (OCPs) including DDT metabolites were investigated in the water and surface sediments from the lower reaches of the Yangtze River to evaluate their pollution and potential risks. Concentrations of OCP residues (ΣOCP₂₄ ranged from 3.07 to 23.70 ng/L in water and 0.67 to 58.80 ng/g dw in sediments) were generally within safe levels, while adverse biological effects are likely from DDT pollution in the lower reaches. HCH and DDT residues dominated the OCPs. High detection rates but low concentrations of some other OCPs, such as chlordane and endosulfan, were detected in both water and sediments. The HCH and DDT residues in the lower reaches primarily originated from historical use of technical HCH and DDT, although additional sources of lindane and dicofol existed in the region. Temporal trends of pesticide contamination levels indicated that HCH concentrations have decreased over the past decades. However, there was no obvious trend of declining DDT concentrations in the sediments from the Yangtze River. The DDT metabolites, DDMU (bis (chlorophenyl)-1-chloroethylene), DBP (dichlorobenzophenone) and DDM (bis (chlorophenyl) methane), were also investigated for the first time in water and sediments from the Yangtze River.

Contamination and health risks of heavy metals in street dust from a coal-mining city in eastern China

We collected street dust from Huainan, a typical coal-mining city in China, to investigate the contamination features and health risks of heavy metals. Concentrations of Co, Cr, Cu, Pb, As, and Sb were generally low to moderate, while pollution levels of Cd and Hg were moderate to high. Concentrations of Cd and Hg were associated with considerable health risks at 64.3% and 58.6% of sites, respectively. In particular, about a fifth of samples had associated high risks as a result of Hg contamination levels. Relative to other urban areas, the street dust from the mining area had no more severe metal pollution, which might be partly attributed to the deposition of coal dust onto street dusts. A source assessment indicated that metals in dust form Huainan were mainly derived from vehicular-related activities, industrial emissions, weathering of coal dust and natural soils, and coal combustion. Although the health risk levels from exposure to individual metals in dusts were low, the non-carcinogenic risks from multiple metals to local children exceeded the acceptable level (1.0), suggesting that the overall risk from exposure to multiple metals in dust is concerning.

Evolution on qualities of leachate and landfill gas in the semi-aerobic landfill.

To study the characteristics of stabilization in semi-aerobic landfill, large-scale simulated landfill was constructed based on the semi-aerobic landfill theory. Consequently, the concentrations of chemical oxygen demand (COD), ammonia nitrogen, and nitrite nitrogen, and the pH value in leachate, as well as the component contents of landfill gas composition (methane, carbon dioxide, and oxygen) in landfill were regularly monitored for 52 weeks. The results showed that COD and ammonia concentrations declined rapidly and did not show the accumulating rule like anaerobic landfill, and remained at about 300 and 100 mg/L, respectively, after 48 weeks. Meanwhile, the descending rate reached 98.9% and 96.9%, respectively. Nitrate concentration increased rapidly after 24 weeks and fluctuated between 220-280 mg/L after 43 weeks. The pH values were below 7 during the first 8 weeks and after that leachates appeared to be alkaline. Carbon dioxide was the main composition in landfill gas and its concentration remained at a high level through the whole stabilization process. The average contents of carbon dioxide, oxygen, and methane varied between 19 vol.%-28 vol.%, 2 vol.%-8 vol.%, and 5 vol.%-13 vol.%, respectively. A relative equilibrium was reached after 48 weeks. The highest temperature in the landfill chamber could amount to 75.8 degrees centigrade.

Deca-brominated diphenyl ether destruction and PBDD/F and PCDD/F emissions from coprocessing deca-BDE mixture-contaminated soils in cement kilns.

The disposal of soil contaminated with polybrominated diphenyl ether (PBDE) was studied using an industrial coprocessing cement kiln. Two tests, Test 1 and Test 2, studied the destruction, removal, and emissions of PBDE in soils with PBDE concentrations of 4160 and 25,000 mg/kg, respectively. Emissions of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were also quantified. The PBDE destruction and removal efficiencies for Tests 1 and 2 were 99.9997% and 99.9998%, respectively. PBDE stack gas concentrations were 39.1 and 85.9 ng/Nm³ for Tests 1 and 2, respectively. The mean PBDD/F TEQ stack gas concentrations related to Tests 1 and 2 were 11.0 and 11.4 pg/Nm³, and PBDFs contributed 60.0-64.2% of the total PBDD/F concentrations. 2,3,7,8-TeBDD made the greatest contribution to the total PBDD/Fs, 40%, of all the homologues. The mean PCDD/F TEQ stack gas concentrations in Tests 1 and 2 were 0.74 and 0.65 pg/Nm³. The total PBDE, PBDD/F, and PCDD/F TEQ at the kiln outlet was 0.006% and 0.001% of the feed material TEQ. Therefore, coprocessing heavily PBDE-contaminated soils in a cement kiln is a highly efficient and environmentally sound treatment technology.

Potential for serious environmental threats from uncontrolled co-processing of wastes in cement kilns.

I many developing countries, the use of cement kilns to coprocess wastes containing heavy metals is thriving and playing an exceedingly important role in solid waste, especially hazardous waste disposal. Co-processed wastes include electroplating sludge, contaminated soil, chromium slag, sludge, hazardous combustible liquid wastes, and garbage. During coprocessing, almost all nonvolatile and semivolatile heavy metals are transferred into cement clinker which causes the heavy metal concentration in the cement to increase significantly. A large portion of the heavy metals in cement will be released into the environment creating a new pollution source and threat to human health. However, the environmental risks have not been realized when most countries are taking advantage of this technology. Therefore, the risks must be focused, and complete pollution control standards should be urgently set to avoid the occurrence of uncontrollable largescale pollution. The coprocessing of waste using cement kilns has been widely and successfully used in the United States, Europe, Japan, and other developed countries for several decades. In many developing countries, there are few high temperature incinerators only for waste disposal; currently, high temperature cement kilns are common and seem to offer an affordable and sustainable treatment alternative. In addition to China, some developing countries that are starting to coprocess wastes using cement kilns include Malaysia, Pakistan, Tanzania, Vietnam, and Sri Lanka. In China, only one cement plant had coprocessed 20 thousand tons of electroplating sludge in 2004. Now 15 cement plants have constructed annexed facilities for coprocessing wastes, and an additional 10 plants are planning to construct relevant facilities. The coprocessing capability of these facilities more than doubled from 2010 to 3.5 million tons in 2011. During waste coprocessing, the hazardous substances contained in the waste are fed into the cement kiln in large quantities. Concerns surrounding the environmental risk from coprocessing have consequently been raised in developed countries. However, these concerns are focused mainly on the hazardous substances emissions in flue gas, such as dioxins and volatile heavy metals; less attention has been given to hazardous substances in clinker and cement products. This is understandable because the coprocessed wastes are typically organic, combustible and liquid wastes with low heavy metal concentrations and are commonly used as alternative fuels. In many developing countries, including China, coprocessed wastes are commonly used as alternative raw materials, and the heavy metal content in these wastes, such as chromium slag, electroplating sludge and municipal solid waste incineration fly ash are also relatively high. When wastes containing heavy metals are coprocessed in cement kilns, almost all nonvolatile and semivolatile heavy metals are transferred into the cement minerals during cement clinker formation (distribution rates of As and Cr in the cement clinker are 99.99 and 99.96%, respectively, and those of Cd and Pb are 99.95%). This causes the heavy metal content in the cement clinker to increase significantly compared with untreated hazardous wastes. For example, the use of cement kiln coprocessing was recommended for the disposal of chromium slag, with the large amounts of hazardous wastes being generated in China resulting in frequent major pollution incidents. When chromium slag (total Cr content of 4.7%, wt. %) was added in a ratio of 2.0% to raw materials, the total Cr content in the clinker reached up to 0.15%, which was an 1500fold increase as compared with the untreated material. Results from our previous studies on the cement kiln coprocessing of arsenic slag showed that when the arsenic slag (total As content of 800 mg/kg) addition to raw materials was 2.2%, the total As content in the clinker increased to 53 mg/kg, which is a 5-fold increase compared with the untreated sample. Another reason why less attention has been paid to the heavy metals in clinker and cement products is that it was generally believed that heavy metals can be stabilized and solidified in cement clinker during high-temperature calcination in cement kilns. However, heavy metals in cement products such as

PCDD/Fs in Fly Ash from Waste Incineration in China: A Need for Effective Risk Management

ncineration has gradually become one of the key means todispose of municipal solid waste (MSW) and hazardouswaste (HW) in China. With great concern for emissions ofpolychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in incineration flue gas, control standards were furtherimproved and many terminal measures applied to pollutioncontrol of flue gas in the country. This resulted in PCDD/Fsbeing further transformed into fly ash. Based on currentdisposal and management, however, PCDD/Fs in the fly ashhave not been effectively eliminated, and will probably reenterthe environment and in turn become a new source of dioxinemission. Therefore, the risks of PCDD/Fs in fly ash should begiven importance and management should be strengthened.Waste incineration is an important source of dioxin emission.In China, PCDD/F emissions in 2004 reached approximately1757.6 g TEQ

Ignoring emissions of Hg from coal ash and desulfurized gypsum will lead to ineffective mercury control in coal-fired power plants in China.

M is an important contaminant when emitted to the atmosphere because of its toxic effects on the environment and human health, persistence in the environment, and global transport in air masses. Mercury has been classified as a global pollutant by United Nations Environment Programme (UNEP). Atmospheric mercury emissions in China rank number one in the world, with emissions from coal-fired power plants the most substantial contributor. From the Chinese Ministry of Environmental Protection, coal consumption for thermal power generation in China was 160 000 t in 2010. The average Hg concentration in coal used for combustion in China is approximately 0.19 mg/kg, so the total Hg emitted (including atmospheric Hg and solid Hg) from coal-fired power plants was approximately 304 t in 2010. The Chinese Ministry of Environment Protection required the percentage of desulfurization equipment in coal-fired power plants to be up to 38.6% by the end of 2010. Mercury removal is achieved mainly through dust removal, desulfurization, and denitrification facilities in China. Assuming that the percentages of mercury removal for an electrostatic precipitator (ESP) and an electrostatic precipitator coupled with wet flue gas desulfurization (ESP+WFGD) are 38.6 and 46.9%, respectively, the overall solid Hg emissions from coal-fired power plants was approximately 138 t in 2010. With the rapid economic development in China, coal consumption in thermal power plants will continue to grow, reaching an estimated 1750 million tons in 2015. If the current dust removal processes and efficiencies remain the same, solid Hg emissions in China will reach approximately 150 t in 2015. Emission standards for air pollutants from thermal power plants implemented in 2012 in China included an emission limit (0.03 mg/m) for Hg pollutants in air from thermal power plants, highlighting the increased emphasis on the removal of mercury from atmospheric emissions of coal-fired power plants in China. It would be expected that more mercury would be present in coal ash and desulfurized gypsum from the increased combustion of coal and the abundance of Hg removal facilities in Chinese coal-fired power plants. From China’s electrical industry statistics, coal ash and desulfurized gypsum yields from coal-fired power plants were approximately 480 million and 5.23 million tons, respectively, in 2010 and the recycling rates of coal ash and desulfurized gypsum were 68 and 67%, respectively. The remaining coal ash and desulfurized gypsum are typically randomly piled and mercury is continuously released to the environment. In China, coal ash is typically used as a mixing material for concrete, an alternative material for cement production and road building. Coal ash used as a mixing material is first mixed with cement to produce concrete and later hydrated. Although mercury in coal ash is immobilized in cement, it can easily be released to the environment (the diffusion coefficient of Hg is 1 × 10−14 m/ s). Mercury is an element with a high volatility. Therefore, in the high temperature environment of a cement kiln, little mercury from coal ash that is used as an alternative material can enter the clinker (tests of more than 60 clinker samples in China indicated that the mercury concentration ranged from 0.01−0.02 mg/kg). Most of the mercury enters the smoke and kiln ash. In Chinese cement companies, kiln ash is circulated within the cement production system, so much of the mercury in the cement kiln system will be emitted in smoke. Mercury in coal ash used for road building can also be leached through long-term washing by rain. Mercury release is also a problem in desulfurized gypsum that is used to produce building materials like gypsum. These problems highlight that if not enough emphasis is put on mercury control in coal ash and desulfurized gypsum, mercury emission control measures at coal-fired power plants will not be effective because the release of mercury is not being controlled. In the overall use of coal ash and desulfurized gypsum, all potential pathways for mercury release should be avoided. For example, restricting the use of coal ash as an alternative material for cement production would allow pretreatment to be performed that could change the mercury species in coal ash and desulfurized gypsum, reducing the mobility of mercury. Finally, a mercury concentration limit in building materials should be incorporated to control mercury concentrations in buildings.

Formulation of criteria for pollution control on cement products produced from solid wastes in China

The process of producing cement products from solid waste can increase the level of pollutants in the cement products. Therefore, it is very important to establish a pollution control standard for cement products to protect the environment and human health. This paper presents acceptance limits for the availability of heavy metals in cement products which have been produced from solid wastes and explains how the limits have been calculated. The approach and method used to formulate these criteria were based on EN 12920. The typical exposure scenarios used in this paper involve concrete being used for drinking water supply pipelines and concrete pavements and are based on an analysis of typical applications of cement in China, and the potential for contact with water. The parameters of a tank test which was based on NEN 7375 were set in accordance with the environmental conditions of typical scenarios in China. Mechanisms controlling the release of heavy metals in concrete and a model for that release were obtained using the leaching test. Finally, based on acceptance criteria for drinking water and groundwater quality in China, limit values for the availability of heavy metals in concrete were calculated.

Pollution characteristics of polycyclic aromatic hydrocarbons in common used mineral oils and their transformation during oil regeneration

The pollution characteristic of polycyclic aromatic hydrocarbons (PAHs) in common used mineral oils, semi-refined oils, refined oils and solid wastes produced during the used mineral oil regeneration process was analyzed. The results showed that total PAHs content in six common used mineral oils was as follows: used engine oil>used quenching oil>used casting oil>used hydraulic oil>used antirust oil>used industrial lubricating oil. Furthermore, this order was dependent on the source of PAHs and oil working temperatures. Additionally, total PAHs content in regenerated oils was as follows: semi-refined oil>refined oil>crude oil, which was related to the catalytic cracking process of crude oil and adsorption refining process of semi-refined oil. The ranking of total PAHs content in regenerated wastes varied depending on the regeneration technology used as follows: waste adsorption sand>acid sludge>waste clay>precipitation sludge>cracked residue. In all types of used mineral oils and regenerated wastes, the maximum and minimum proportions of the total PAHs content were composed of 2-3 ring-PAHs and 5-6 ring-PAHs, respectively. The majority of PAHs in the used mineral oils entered into regenerated wastes during regeneration process, while a small number remained in the regenerated oil.