Chemical states of arsenic contained in sewage sludge incineration ash and insolubilized material

Journal of Material Cycles and Waste Management - The chemical states of arsenic contained in 4 kinds of sewage sludge incineration ash and insolubilized materials are analyzed using a leaching...     

Applicability of LIVE/DEAD BacLight stain with glutaraldehyde fixation for the measurement of bacterial abundance and viability in rainwater

Rainwater contains substantial bacteria and rain is an efficient pathway for the dissemination of bacteria from the atmosphere to land and water surfaces.However,quantitative information on rainwater bacteria is very limited due to the lack of a reliable method.In this study,the epifluorescence microscopy enumeration with the LIVE/DEAD BacLight Bacterial Viability Kit stain was verified to quantify the abundance of viable and non-viable bacterial cells in rainwater,with the 4',6-diamidino-2-phenylindole(DAPI) stain for the reference of total cell counts.Results showed that the total counts of bacterial cells by LIVE/DEAD BacLight staining were consistent with those by DAPI staining,and the average detection efficiency was(109 ± 29)%.The ratio of cell count with glutaraldehyde fixation to that without fixation was(106 ± 5)%on average.The bacterial concentration in negative control was usually an order of magnitude lower than that in rainwater samples.However,in case of small precipitation,the abundance in negative control could be more than that in rainwater samples.These results indicate that the enumeration with LIVE/DEAD BacLight bacterial viability assay coupled with glutaraldehyde fixation and careful negative control investigation is an approach applicable to the measurement of the concentration and viability of bacterial cells in rainwater.     

Characteristics of azaarenes and dioxins in gases emitted from waste incinerators

In this study, we propose an analytical method to determine the fourteen of azaarenes present in flue gas samples collected according to Japanese Industrial Standard K 0311, which designates the method for the determination of dioxins in flue gas. Azaarenes can be analyzed using the acidic water phase after shaking extraction with dichloromethane, which is unnecessary for dioxin analysis. Flue gas samples were obtained from 24 waste incinerators in Japan, and azaarenes were detected in all the flue gas samples (0.21–3800 μg/m³ _N). The most abundant of the detected compounds were quinoline and isoquinoline. The concentration of azaarenes had a tendency to increase with that of polychlorinated dibenzo-p-dioxins and dibenzofurans. The isomer distribution of heptachloro-dibenzofurans (HpCDFs) was calculated using the computed Gibbs energy of formation (ΔG _f ) obtained by the semiempirical molecular orbital method at various temperatures. The calculated isomer distribution was fitted to the measured value of HpCDFs. It seems that the temperature obtained from the fitting calculations is an indicator of the cooling capacity of the combustion gas in an incinerator. The computed ΔG _f also explained the measured isomer distributions of azaarenes. It is suggested that the isomer distribution of azaarenes in the combustion process is thermodynamically controlled. This work was presented in part at the International Conference on Combustion, Incineration/Pyrolysis, and Emission Control, 2006, Kyoto     

Characterization of trace constituents in landfill gas and a comparison of sites in Asia

Because landfill gas (LFG) contains an abundance of methane, the utilization of LFG as a renewable energy source is becoming popular in many countries. LFG, however, contains various trace constituents, some of which may pose problems during utilization. For example, siloxanes and halogenated volatile organic compounds (VOCs) can cause difficulties when present in the fuel of gas engines. In addition, many VOCs and mercury have harmful effects on human health, especially on the health of workers at landfill sites and people living near the landfills. Energy recovery from LFG is expected to make great progress in the near future, particularly in Asia, but we found little information on the trace constituents of LFG in this region. Therefore, we sought to characterize the trace components in LFG generated in two landfill sites in China and one site in Japan, to determine the typical concentrations of these trace components in LFG, and to compare their concentrations among landfill sites in Asia. We concluded that the trace components in LFG at the sites studied were mainly siloxanes generated from sewage sludge and harmful benzene, toluene, ethylbenzene, and xylene compounds from petroleum products.     

Non-intrusive characterization methods for wastewater-affected groundwater plumes discharging to an alpine lake

Streams and lakes in rocky environments are especially susceptible to nutrient loading from wastewater-affected groundwater plumes. However, the use of invasive techniques such as drilling wells, installing piezometers or seepage meters, to detect and characterize these plumes can be prohibitive. In this work, we report on the use of four non-intrusive methods for this purpose at a site in the Rocky Mountains. The methods included non-invasive geophysical surveys of subsurface electrical conductivity (EC), in-situ EC measurement of discharging groundwater at the lake-sediment interface, shoreline water sampling and nutrient analysis, and shoreline periphyton sampling and analysis of biomass and taxa relative abundance. The geophysical surveys were able to detect and delineate two high-EC plumes, with capacitively coupled ERI (OhmMapper) providing detailed two-dimensional images. In situ measurements at the suspected discharge locations confirmed the presence of high-EC water in the two plumes and corroborated their spatial extent. The nutrient and periphyton results showed that only one of the two high-EC plumes posed a current eutrophication threat, with elevated nitrogen and phosphorus levels, high localized periphyton biomass and major shifts in taxonomic composition to taxa that are commonly associated with anthropogenic nutrient loading. This study highlights the need to use non-intrusive methods in combination, with geophysical and water EC-based methods used for initial detection of wastewater-affected groundwater plumes, and nutrient or periphyton sampling used to characterize their ecological effects.     

Human factors and tidal influences on water quality of an urban river in Can Tho, a major city of the Mekong Delta, Vietnam

In this study, we focused on water quality in an urban canal and the Mekong River in the city of Can Tho, a central municipality of the Mekong Delta region, southern Vietnam. Water temperature, pH, electrical conductivity, BOD₅, COD_Cr, Na⁺, Cl^?, NH₄ ⁺?N, SO₄ ^2??S, NO₃ ^??N, and NO₂ ^??N for both canal and river, and tide level of the urban canal, were monitored once per month from May 2010 to April 2012. The urban canal is subject to severe anthropogenic contamination, owing to poor sewage treatment. In general, water quality in the canal exhibited strong tidal variation, poorer at lower tides and better at higher tides. Some anomalies were observed, with degraded water quality under some high-tide conditions. These were associated with flow from the upstream residential area. Therefore, it was concluded that water quality in the urban canal changed with a balance between dilution effects and extent of contaminant supply, both driven by tidal fluctuations in the Mekong River.     

Dietary patterns and blood levels of PCDDs, PCDFs, and dioxin-like PCBs in 1656 Japanese individuals

The association between dietary patterns and blood dioxin levels has not been fully investigated. The present study population consisted of 755 men and 901 women (aged 15-73 years) living in 90 different areas of 30 prefectures of Japan. Dietary habits were assessed by inquiring about the consumption frequency of 28 foods, food groups and beverages. In addition, the blood levels of 29 polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs), and dioxin-like polychlorinated biphenyl (DL-PCBs) congeners were determined by high-resolution gas chromatography/mass spectrometry. The median total toxicity equivalent (TEQ) in the blood, which was calculated on the basis of the toxicity equivalency factors of WHO (2005), was 16 pg TEQ g⁻¹ lipid. Principal component analysis identified five dietary patterns: Healthy diet (high intake of vegetables and fruits); Meat/High fat intake (high intake of meat, meat products, and eggs); Seafood and Alcohol (high intake of fish, shellfish, and alcoholic beverages); Miscellaneous; and Milk products and Alcohol intake (high intake of milk, Milk products, and alcoholic beverages). After adjusting for sex, age, body mass index, and smoking habits, the Seafood and Alcohol pattern scores were significantly related to higher blood levels of total TEQ and PCDDs/PCDFs/DL-PCBs, and the Milk products and Alcohol pattern scores were correlated with higher blood levels of DL-PCBs. More detailed analysis showed that the intake frequencies for alcoholic beverages and seafood were independently and positively associated with total TEQ and the TEQ of PCDFs and DL-PCBs. The association between alcoholic beverage intake and PCDDs was also significant. Analysis of dietary patterns may be useful for identifying the dietary characteristics of individuals with a high dioxin body burden.     

Seasonal change of PCDDs/PCDFs/DL-PCBs in the water of Ayase River, Japan: pollution sources and their contributions to TEQ

In Japan, Ayase River is one of the most polluted rivers by PCDDs, PCDFs and dioxin-like PCBs, which are referred to as dioxins in this paper. The water samples of the river were collected once per month for a year, and dioxins were analyzed to examine the dioxin sources and their contributions to toxic equivalent (TEQ). The WHO-2006 TEQs ranged from 0.26 to 7.0 pg-TEQ L⁻¹ and the average was 2.7 pg-TEQ L⁻¹; eight of 12 samples exceeded the environmental quality standard in Japan (1.0 pg-TEQ L⁻¹). The TEQ value was high during the irrigation period from May to August. The most part of the dioxins in the river water existed in suspended solids (SS) and it seemed that the river received water with highly-dioxin-contaminated SS in the irrigation period. The homologue profiles of the water samples suggested that the dioxins were influenced by pentachlorophenol (PCP) and chlornitrofen (CNP) formulations which were widely used as herbicides for the paddy fields in Japan. According to TEQ apportionment estimated by using indicative congeners, the TEQ was mainly contributed by PCP. Moreover, it was also shown that the TEQ contributions of PCP and CNP formulations increased along with the increase of the total TEQ and the TEQ contribution was dominated by these herbicides during the irrigation period. Therefore, it was concluded that the herbicides-originated dioxins run off from the paddy fields into the river during the irrigation period and increased the dioxins level in the river water. The result from the principal component analysis was consistent with these conclusions.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice straw smoke and their origins in Japan

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) contained in the smoke generated from rice straw burning in post-harvest paddy fields in Japan were analyzed to determine their congener profiles. Both the apportionment of toxic equivalent (TEQ) by using indicative congeners and the comparison of the homolog profiles showed that the PCDDs/PCDFs/DL-PCBs present in the rice-straw smoke were greatly influenced by those present as impurities in pentachlorophenol (PCP) and chlornitrofen (CNP, 4-nitrophenyl-2,4,6-trichlorophenyl ether) formulations that had been widely used as herbicides in paddy fields in Japan. Further, in order to investigate the effects of paddy-field soil on the PCDDs/PCDFs/DL-PCBs present in rice-straw smoke, PCDD/PCDF/DL-PCB homolog profiles of rice straw, rice-straw smoke and paddy-field soil were compared. Rice-straw smoke was generated by burning rice straw on a stainless-steel tray in a laboratory. The results suggested that the herbicides-originated PCDDs/PCDFs/DL-PCBs and the atmospheric PCDDs/PCDFs/DL-PCBs contributed predominantly to the presence of PCDDs/PCDFs/DL-PCBs in the rice-straw smoke while the contribution of PCDDs/PCDFs/DL-PCBs formed during rice straw burning was relatively minimal. The major sources of the PCDDs/PCDFs/DL-PCBs found in the rice-straw smoke were attributed primarily to the paddy-field soil adhered to the rice straw surface and secondarily to the air taken by the rice straw. The principal component analysis supported these conclusions. It is concluded that rice straw burning at paddy fields acts as a driving force in the transfer of PCDDs/PCDFs/DL-PCBs from paddy-field soil to the atmosphere.     

Polycyclic aromatic hydrocarbons (PAHs) in the aerosol in Beijing, China, measured by aminopropylsilane chemically-bonded stationary-phase column chromatography and HPLC/fluorescence detection

We developed a useful analytical method for the determination of polycyclic aromatic hydrocarbons (PAH) concentrations in the aerosol of China. We used an accelerated solvent extraction (ASE) method for the extraction of PAHs from the aerosol samples, in order to reduce the extraction time and the solvent volume used. The optimum purification method was developed, with aminopropylsilane chemically-bonded stationary-phase column chromatography, in order to remove many co-extractives which cannot be removed by conventional purification methods using silica-gel column chromatography. HPLC/fluorescence detection (FLD) was adopted as the analytical method, because it has very high sensitivity to PAH and it is easy to install, operate, and maintain as compared with GC/MS. With the analytical method developed in this study, the recovery and precision (RSD) for most of the PAHs ranged from 75% to 129% and from 2.8% to 22.7%, respectively. The concentrations of PAHs in the aerosol samples collected from October 2003 to April 2005 in Beijing, China were determined using the newly developed method. SigmaPAHs, which is the sum of the concentrations of all detected PAHs, was 177.8 +/- 239.9 ng m(-3) (n = 64). The SigmaPAHs concentration in the heating season (305.1 +/- 279.0 ng m(-3), n = 33) was 7.2 times higher than that in the non-heating season (42.3 +/- 32.0 ng m(-3), n = 31). These strong seasonal variations in atmospheric PAH concentration are possibly due to coal combustion for residential heating in winter.