Advanced Materials Research Vol. 878

Abstract: Baihua Lake is a key drinking water source for Guiyang City located on Guizhou Plateau in southwest China, however it has been seriously contaminated with various contaminants, such as nitrogen, phosphorus, and heavy metals. To solve this problem, some researchers have recommended dredging the lake sediment to remove these contaminants. The present research was aimed to assess the potential risk of five selected heavy metals (Cd, Cu, Cr, Hg and As) if the sediment dredging measure was taken for remediation of this water body. Core sediments collected from the site Guanyinshanzhuang were used to simulate the release of heavy metals in sediment from Baihua Lake if sediment dredging was carried out. The core sediments were dredged at 10 cm, 20 cm and 30 cm levels. The core sediments were then put into the lake again after simulation dredging to investigate their release potential in one day, five days, nine days and fifteen days. The mobility of selected heavy metals in the sediments were determined using the toxicity characteristic leaching procedure (TCLP) developed by the United States Environmental Protection Agency (USEPA). The results indicated that the release potential of the heavy metals varies with dredging depth and the lasting time after dredging. Cr and As showed the lowest release ability among the heavy metals under study followed by Cu. The release amount of Cd increased with the lasting time after dredging. Hg showed no clear trends of release at 10 cm dredging depth. At 20 cm and 30 cm dredging depth, Hg presented a small release in the five days after simulation dredging, and then no release in the following ten days. In fifteen days after simulation dredging, the percentages of the heavy metals extracted with TCLP were in the order of Cd (8.85%) > As (3.41%) > Cu (1.37%) > Hg (0.79%) > Cr (0.61%) at dredging depth of 10 cm, Cd (10.22%) > Hg (2.73%) > Cu (1.74%) >As (1.47%)> Cr (1.41%) at dredging depth of 20 cm, and Cd (10.38%) > As (2.07%) > Hg (2.51%) > Cu (1.74%) > Cr (0.87%) at dredging depth of 30 cm.

Abstract: Risk-based method has been increasingly frequently used by regulators and managers in modern landfill to scientifically manage solid waste and reduce its environmental hazards. As far as hazardous waste landfill is concerned, the main risk can be identified as the leakage of leachate. To quantify the uncertainties and its influences on risk assessment of leachate leakage, EPACMTP model with the involvement of Monte Carlo method is used to propagate the randomness of input parameters; Fault tree analysis method is employed to compute the uncertainties of liner damage; and the last, health risk assessment model was also integrated into to form a holistic model of leakage risk assessment.. A hazards waste landfill located in the southwest China is taken as a case study. The assessment result indicates that 1) the main exposure pathway is oral intake;2) The total non-carcinogenic risks for adult and for child are, accordingly, equal to 0.68 and 0.75, which under most circumstance is acceptable.

Abstract: The aim of the paper is the research on the nondestructive detection of Japanese abandoned chemical weapons (JACWs) in the water. Distribution and characteristics of JACWs in the lakes and rivers in China, the task, the equipment and technical requirements of the JACWs nondestructive detection in the water are presented. Practical methods and procedure of JACWs nondestructive detection in the water are given by confirmed with verification test. Two living examples of JACWs nondestructive detection in the water are also presented. In the practice of JACWs detection, it is proved that this method and procedure of JACWs detection in the water has advantages such as high efficiency, low risk, good maneuverability and good effectiveness.

Abstract: Liquid crystals, contained in Liquid Crystal Display (LCD), would cause undesirable impacts on the environment and human health if not treated properly. Converting the waste liquid crystal into harmless product has aroused worldwide attention. In the present work, hydrothermal technology was applied to treat the liquid crystal of 4-octoxy-4'-cyanobiphenyl, which is one of the most common used liquid crystals in LCDs. The experiment was carried out in a 5.7 mL stainless tube reactor and heated by an oven. The effect of reaction temperature and reaction time on degradation rate was evaluated and the analysis was conducted with High Performance Liquid Chromatography (HPLC). The degradation products in liquid phase were analyzed with Gas Chromatography/Mass Spectrometer (GC/MS). Results indicate that the degradation rate improved along with the increase of reaction temperature and reaction time. At 300 C and with the reaction time of 90 min, 99.8% of 4-octoxy-4'-cyanobiphenyl could be degraded into simple and environmental innocuous products and its environmental risks were finally eliminated.

Abstract: Simulated municipal solid waste (MSW) based on the actual proportional characteristics of MSW was loaded into a simulated leachate recirculation bioreactor landfill and the abundance of common and tolerant microbes exposed to dibutyl phthalate (DBP) were investigated in the initial, acidic and methanogenic phases. The results showed that the abundance of bacteria was greatest, while that of actinomycetes was smallest. The growth of microorganisms was not significantly inhibited by DBP during the initial phase; however, the growth of actinomycetes and fungi was inhibited during both the acidic and methanogenic phases, and the inhibition of actinomycetes was greater than that of fungi. When the DBP concentration was 5.0 g l^-1, the inhibition ratio against actinomycetes was 89.5% and 80.9% in the refuse from the acidic phase and methanogenic phase, respectively, while it was 86.2% and 51.0%, respectively, against fungi during the same period. The toxic effects of DBP on microorganisms in refuse occurred in the order of actinomycetes > fungi > bacteria. In addition, the populations of bacteria, fungi and actinomycetes were significantly and positively correlated with dehydrogenase activity, but negatively correlated with the VSS and BDM of refuse (P<0.01).

Abstract: To study the removal capacity of modified fly ash in wastewater containing mercury ions under different conditions, the dust from a calcium carbide furnace was added to fly ash, and the pyrogenic process was employed to modify the fly ash. The result indicated that the wastewater had a pH value of 9, the modified fly ash dosage was 0.2 g, the adsorption equilibrium time was 40 minutes, the reaction temperature was 30 °C, and the removal rate could reach 91.9%. Using modified fly ash in polyvinyl chloride production via the calcium carbide method to remove mercury-containing wastewater can help meet the government-prescribed emission standard. This method has advantages such as positive treatment effect, simple operation, and low operating cost.

Abstract: Lanzhou is one of the largest and most important cities in the west part of China. Similar to other megacities in China, Lanzhou produces a lot of SFLs (Spent Fluorescent Lamps) each year too. SFLs in Lanzhou come from four sources: Industrial, commercial, municipal and residential. Consumers of fluorescent lamps have different concepts on how to manage SFLs well. These concepts are established based on their own social cultural norms, moral values and environmental awareness. Most of them are both ineffective and unscientific; SFLs are discarded regularly into trash and buried in landfills. So how to manage SFLs efficiently and effectively becomes a great challenge. So far, no professional companies can collect, dispose, and manage with SFLs well in Lanzhou area. It is necessary and urgent to establish management funds for collecting and disposing SFLs. This article has built a recycling management mode of SFLs, and has done some explanations on how to implement the model.

Abstract: Healthcare waste management represents a challenge in China due to insufficient legislation and financial investment, lack of awareness and effective regulations, lack of trained clinical staffs in the waste management framework etc. This study considered the issues of existing healthcare waste management practice and put forward the policy suggestions.

Abstract: Polybrominated diphenyl ethers (PBDEs), especially pentaBDE and decaBDE have been extensively used as flame retardants in plastics of most electronic equipment. However, PBDE congeners have been found in the environment, in wildlife and in human body worldwide with evidences that they pose risks both to human health and to the entire ecosystem. China has become an important pentaBDE and decaBDE production country because of the increasing domestic demand due to rapid development of electronic industry in recent years. Although pentaBDE was phased out in 2004, decaBDE still remains in production and is used in electrical industry. Additionally, large amounts of plastics containing these pollutants from waste electrical and electronic equipment (WEEE) are generated in China each year and their disposal has been a vital environmental challenge. Machaniclal recycling, fedlock recycling and landfilling are three main means of disposal of WEEE plastics. This article reviews the production of PBDEs, the amounts of WEEE and the disposal of WEEE plastics worldwide, with a special focus on China. The state of the emission of PBDEs and highly toxic polybrominated dibenzo dioxins/furans in the process of disposal is summed up based on previous studies. This article recommends that mechanical recycling should be the main means of disposal of WEEE recycling with regards to the summaries, the current practices and the status in China.

Abstract: The rational layout of emergency facilities has a critical effect on the reduction of the damage caused by the disasters of hazardous waste leakage. This paper proposes an emergency covering location model adopting arc covering continuous decline function. According to the features of the arc covering emergency location model, a heuristic algorithm is adopted to solve the model. Numerial examples are used to verify the validity of the proposed model and algorithm. It is concluded that building more emergency points should combine with enhancing network coverage.