The rapid emergence of pathogens has created a threat to the drinking water industry. Consequently, the microbiological quality of drinking water is of a major concern to consumers, water suppliers, regulators and public health authorities. As a result, better monitoring methods for waterborne pathogens are needed and those based on appropriate molecular technologies attract dramatically the attention. This review attempts to summarize the most recent progress and offers a comprehensive view of pathogens in water supply system that have been known and/or emerged recently, and the emerging molecular technologies developed to detect them.
Recently, various kinds of chemicals have been produced and released to environment by human activities, and they caused various environmental problems. Therefore, environmental risks of chemicals should easily and quickly be examined. In this study, neural network was developed to predict cytotoxicity of human liver cells. Cytotoxicity data of 57 chemicals investigated by using in vitro cell survival assay performed by human liver cells: HepG2 was used for training neural networks. As input data for the neural network partition coefficient octanol-water (logPow), dissociation constant (pKa), molecular weight (M.W.), and concentration of the chemicals were used. Resultant cell survival data were derived on neural networks in a personal computer. In addition, the chemicals were classified into some groups in terms of chemical structure. Leave-one-out test was performed to validate the correlation between data experimental and predicted by the neural network for each chemical groups. There was a significant correlation between cell survival data experimental and predicted. As classified chemicals into smaller group according to the chemical property and structure can estimate the toxicity quantitatively in dose response manner.
The micronuclei test with gills of Japanese medaka (Oryzias latipes) was developed by modification of the traditional method. The effectiveness of this assay was confirmed with medaka exposed to Benzo[a] pyren, and the time course and concentration-dependent patterns of micronuclei induction were discussed. Finally, this new method was applied to effluent samples from 3 landfill sites and 1 chemical factory. All of raw leachate samples induced micronuclei significantly, which were reduced through treatments. The fact that the significant induction of micronucleated cells was observed when fishes were exposed to lower concentration of effluents than that of LC50 suggests the importance of genotoxicity monitoring with this test.
This paper proposed a method to estimate the chemical composition of calcium compounds in the KOSA particles according to the carbonate equilibrium system in an acidic solution. The calcium compounds in the KOSA aerosols were classified into two categories in terms of the neutralizing capacity of acidic substances in the atmosphere, i.e. the portion that contributes to neutralization and the portion that does not. It was shown that the former might consist of carbonates and that the latter might consist of neutral salts such as sulfate and nitrate. The ratio of carbonate content to total soluble cation content in the KOSA aerosol collected in Toyama, Japan, which was also estimated by a chemical equilibrium established in this study, implied that fairly large portion of the calcium carbonate in KOSA aerosols could be regarded as having reacted with acidic pollutants in the atmosphere.
For a comprehensive evaluation on the PET bottle recycling, cost and major environmental load including energy consumption and emissions of CO2, SOx and NOx related material recycling system and other three alternatives (incineration, thermal recovery and direct landfill) were estimated. Based on general lifecycle inventory over the PET bottle disposal or recycling stages, material recycling system was found to have a conclusive advantage on environmental load reduction. Ratios of environmental load related to material recycling system to those related to other alternatives were 4 to 10%. On the other hand, disadvantage of material recycling system on the cost was also indicated. Ratios of the cost covering material recycling system to those covering other alternatives were between four and ten. As to promote the material recycling system for PET bottle waste management with environmental load reductions, several types of economic policies sustaining disposal or recycling cost balance should be needed.
In order to extract polycyclic aromatic hydrocarbons (PAHs) having 3 to 6 rings from soil, efficiently and quickly, three ultrasonic extraction methods were compared by using a HPLC/FLD method. The total concentrations of 13 kinds of PAHs were in the order, Method 1 (benzene/ethanol, 3:1) › Method 2 (methanol) › Method 3 (hexane), although PAHs having 3 and 4 rings were extracted more efficiently by Method 2 than Method 1. Furthermore, Method 1 showed higher precision than the other methods. These results suggest that Method 1, which is used for atmospheric PAHs, is also a useful method for PAHs in soil.
Since coal and oil fired plants are one of the major sources of sulfur dioxide emission to the atmosphere, it has been required to develop desulfurization processes with a lower cost and a smaller energy consumption than the conventional wet limestone flue gas desulfurization processes (FGD). The catalytic SOx oxidation process (CASOX Process) is an innovative flue gas desulfurizing process that demonstrates a high performance in desulfurizing sulfur dioxide from flue gas by a newly developed desulfurizing catalyst. The flue gas is desulfurized in passing through the catalytic layer when the sulfur dioxide is oxidized to dilute sulfuric acid on the surface of the catalyst with oxygen and water vapor in the flue gas. The surface of the activated carbon as a catalyst is treated to have water-repellency, so that the dilute sulfuric acid produced on the surface of the catalyst can be separated from the catalyst rapidly and continuously. This treatment made the catalyst possible to be operated without regeneration procedures , so it can be operated without alkaline. Demonstration tests were conducted on the pilot plant installed at Toyama Shinko Power Plant of Hokuriku Electric Power Company in order mainly to confirm the practical application of this process to a coal fired power plant. Through the treatment of the flue gas from the coal fired power plant, CASOX Process maintained more than 95% of SO2 removal rate and stable over 15,000h of desulfurization performance. The demonstration tests also revealed that CASOX Process has the following advantages. First, the process can reduce energy consumption compared with the conventional FGD process, because of the small number of the equipments, especially on the point that no large fans and circulation pumps are required. Second, the process can be easily operated and maintained because of its simple configuration. Third, this process can be operated without alkaline because sulfuric acid is produced as a by-product. The first commercial plant of CASOX Process has been operated from April 2003 successfully.