Applied Mechanics and Materials Vol. 768

Abstract: The objective of this study was to characterize the photodegradation ability of pentachlorophenol (PCP) in β-cyclodextrin (β-CD) soil washing solution. After contaminated soil remediation by β-CD soil washing method, solution contained target contaminant was further treated with photodegradation technique. Degradation processes with Xe lamp to simulate natural sun light was investigated under different temperature, and various aeration rate. TiO₂ employed as photocatalyst was also tested in the soil washing system. The result demonstrated that photodegradation rate of PCP in soil washing solution was related to the aeration rate. The reaction could be slightly accelerated by increasing the temperature. TiO₂ adding will decrease the degradation speed, while using it together with H₂O₂ will extremely increase the degradation rate of the target contaminant in this condition.

Abstract: This study is aimed at four typical oil production plant station of Daqing oilfield of China petroleum (union station, transfer station, production wells and injection wells) ,where the surrounding shallow soil environmental background (pollution) status.Collecting the information nearby the typical stations within the scope of evaluation of geological and hydrogeological information and the surrounding soil environment information of the sensitive area.Building a conceptual model of the site.According to the characteristics of pollutants,pollution,the site conditions and environmental sensitivity,select and optimize the economic and applicable remediation of petroleum pollution inferring to the different situations of soil.

Abstract: Taking Pingzhai Village in Sanming City of Fujian Provice as the researching area, the village has already outbroken Children’s blood lead exceeding and cause a lot of damage to local children. In order to reveal the reason for this serious consequence and assess the environmental risk of Pb, 24 soil samples including 12 from parent material layer and 12 from the corresponding surface layer and 4 groundwater samples are collected. The Tessier sequential extraction method is applied to analyze different speciation of Pb in soil, and Risk Assessment Code (RAC) and Ratio of Secondary Phase and Primary Phase (RSP) are both applied to evaluate Pb contamination degree and ecological risks. The results show that: the concentration of Pb in soil samples exceeds the soil Pb background values of Fujian Province, and the overall concentration of Pb shows a rising trend from the surface to parent material layer, then their accumulated pollution index range from 5.4 to 54.9 in surface layer and 4.7 to 68.1 in parent material layer. Coefficients of variation of Pb in surface and parent material layer are 79% and 86%, respectively. The lead in soil can be divided into 3 chemical speciation containing T1 (exchangeable speciation and carbonate bounded form), T2 (potential ecological risk form) and T3 (residual speciation) and Pb in soil mainly exists in T2 and T3. There shows a significant positive correlation between T2 or T3 and the total amount of Pb in soil. Pb concentration in groundwater has exceeded limited value of Standards for Drinking Water Quality. RAC and RSP ecological risk assessment results indicate that: environmental risk level of RSP is higher than it of RAC, and the contamination degree and potential environmental risk level of parent material soil are higher than them of surface soil applied by the two assessment methods.

Abstract: The estimation of odorous compounds production from landfill sites is a very complicated task because of the various chemical and biological species that exist in landfill gas. In this study, the correlative concentration between ethanol and other odorous compounds emitted from the working surface at a landfill in Beijing was analyzed. Gas sampling was conducted at the landfill on several selected days from March 2012 to March 2014, representing the different periods throughout the two years. A total of 41, 59, 66, 54, 63, 54, 41, 42 species of trace compounds were identified and quantified during eight sampling activities, respectively, and a total of 86 species of trace compounds were identified and quantified all together. The measured trace compounds were classified into six different categories (Oxygenated compounds, Halogenated compounds, Terpenes, Sulfur compounds, Aromatics and Hydrocarbons). The total average concentrations of the oxygenated compounds, sulfur compounds, aromatics, halogenated compounds, hydrocarbons and terpenes were 2.450 mg/m³, 0.246 mg/m³, 0.203 mg/m³, 0.319 mg/m³, 0.530 mg/m³, 0.217 mg/m³, respectively. The correlative concentrations of the odorous compounds with respect to the concentration of ethyl alcohol (ethyl alcohol taken 1000 ppm total) were determinate, which could make great significance to the estimation of odorous compounds emitted from the landfill sites.

Abstract: Lead-acid batteries were widely used in many industries as important power supply devices for military and civil industries, transport and shipment devices owing to its advantages of low cost,high performance and safety. According to statistics, most lead-acid batteries can reach 1-2 years life under operating conditions, generating millions of used lead-acid batteries each year in China, which caused economic and environmental losses if not properly treated. The changes of physico-chemical properties in the process of operation of lead-acid battery were summarized in this paper. The corrosion and deformation of grids, water loss in electrolyte, aging of separators, corrosion of plates and irreversible sulfation were the main physico-chemical properties changes resulting in battery failure. In the homogeneous acidic medium, the grid of the lead-acid battery corroded away, one side was dotted distribution, and the other side was interlaced net shape. The corrosion of grids and incomplete reaction may lead to the water loss in electrolyte. What’s more, there existed a series of chemical reactions that reducing the battery capacity and leading to the failure of batteries, such as the aging and elastic collision of separators and irreversible sulfation. By analyzing the physico-chemical properties changes in the process of operation, the study supplied the direction for the specification of operating conditions and the extending of service life of lead-acid battery. The basic theories were provided for the repair, regeneration and recovery of lead-acid batteries.

Abstract: Waste pollutions and disposal problems of transformer substation in electric power industry were paid more and more attention by people. Waste transformer oil contained many kinds of toxic substances. Transformer oil belongs to hazardous waste according to the definition of the United Nations Environment Programme (UNEP) and the National Hazardous Waste Inventory in China. The related research on environmental pollutants in waste transformer oil was less. The composition and content of particular pollutants which is harmful to human health and ecological environment in waste transformer oil was studied in this paper. Gas chromatography-mass spectrometry was chosen to detect the organic pollution composition and content of particular pollutants in transformer oil, based on investigation and analysis. Transformer oil samples running different time under 10KV voltage level were detected. The test results showed that with turbidity of oil rising, the content of polycyclic aromatic hydrocarbons in waste transformer oil increased, while benzene content changed in the opposite trend. Complex composition, different origin and different operating conditions were the reasons of difficulty to separate organic components in transformer oil during detection. This study is helpful for safe disposal of waste transformer oil. And it also can provide some theoretical support to eliminate the harm of the polycyclic aromatic hydrocarbons and benzene series.

Abstract: Polychlorinated biphenyls (PCBs) are the organic pollutants that of persistence, fat soluble and character such as biological toxicity, widely distributed. It also showed a highly persistent in the environment, strong enrichment and high biological toxicity, having the serious harm to human health and ecological environment. The final destination of PCBs in the environmental system is soil and sediment due to its highly distribution coefficient between sediment and water. PCBs in soil is difficult to decompose and has strong adsorption. Therefore, the detection and remediation of PCBs in soil is very critical. PCB_S in soil detection technologies becoming matured at present. Such as dual column gas chromatography analysis method, GC – MS, enzyme immunoassay for PCBs detecting have been widely used. Low cost, high resolution and high accuracy detection technology has been more and more attention. For the remediation technologies of contaminated soils, chemical remediation, bioremediation technologies developed fast. Efficient, economic and environmental multiple remediation method, such as elution pretreatment on contaminated soil, combination of multiple remediation techniques are the development direction of the future. Based on the analysis on detection and remediation technologies of PCBs in soil. The principle and suitable condition of different detection methods and remediation technologies of PCBs in soil was studied in this paper. To provide technical support to remediation the PCB-contaminated soils.

Abstract: The health care organization and hospital are the major sources that release mercury into the environment. In 2009, in our previous study, we observed that 38% and 24% of the total 797 numbers of mercury containing devices used at the health care organizations were thermometers and sphygmomanometers, respectively. Therefore, it is found based on our calculation that about 13 pieces of thermometers have been broken per day in the center clinics and resulting release in 0.4-1.2 kg/year mercury intothe environmental air. We also measured the potential quantity of released mercury from 2 ng/m³ mercury vapor using a portable atomic absorption spectrometer (AAS). Each measurement in total 16 health care organizations, which we involved in the present study, was done at the following three points: the background levels, the waste storage area of clinic, the storage area for mercury device and fluorescent lamps. As a result, the average concentration of indoor mercury vapor is measured to be 213 ng/m³. However, we found that the highest concentration (2682 ng/m³) of indoor mercury vapor at the waste storage area of health care organizations. As this data compared to that of the USA ATSDR minimal risk level (MRL, 0.2 μg/m³), no significant differences (p>0.05) is observed. This observation indicates that the health care organizations are considered as the main sources of mercury indoor environmental air. Therefore, further research investigations should be focused on the improvement of mercury containing waste management at the clinics.

Abstract: Vinyl acetate, as an important kind of organic chemical raw materials, often adopts the distillation system to separate finished product from raw product. In addition to target products, some residues are produced in the process of distillation, which have a strong damage to the environment, therefore these residues are identified as hazardous wastes to manage and dispose in China. This paper, combined with literature analysis and site investigation, mainly studied production characteristics and particular pollutants of vinyl acetate distillation residue (solid and liquid). To conduct the analysis of the physical and chemical properties of distillation residue, and this paper applied the Gas chromatography-Mass spectrometry (GC-MS) to detemine main particular pollutants, containing Acetic Acid (relative peak area value of 63.47%), 1,1-Ethanediol Diacetate, Crotonic Acid, etc. Meanwhile, this paper can draw another conclusion that treatment and disposal of resource utilization distillation can make more significantly and efficiently use of vinyl acetate distillation residues through the technological contrast of GC-MS.

Abstract: Lime used to treat flue gas from incinerators and organic chelating agents used to remove heavy metals from fly ash create a highly saline and alkaline environment at landfill sites, causing nitrification inhibition that hampers nitrogen treatment and generating refractory COD in the processes of organic stabilization by microbes and leachate treatment. The authors analyzed organic chelating agents and fly ash treated with the chelating agents, and monitored leachate from lysimeters, or simulated landfills. The results showed that organic chelating agents acted as nitrification inhibitors, and that higher water levels in landfill layers resulted in higher concentrations of thiourea and refractory COD, which are chelating compounds, hindering leachate treatment.