Search

The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl3∙6H2O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl-K X-ray absorption near edge structure (XANES) spectroscopy. These results showed the thermal formation mechanism of aromatic-Cl compounds in the solid phase with ferric chloride. We attribute the formation of aromatic-Cl compounds to the chlorination of carbon, based on the oxychlorination reaction of FeCl3 at temperatures in excess of ca. 300 °C, when the carbon matrix is activated by carbon gasification, catalyzed by Fe2O3, and surface oxygen complexes (SOC) generated by a catalytic cycle of FeCl2 and FeOCl. Chemical changes of trace iron in a thermal process may offer the potential to generate aromatic-Cl compounds in the solid phase. [ABSTRACT FROM AUTHOR]

Abstract: Oxidative mutation is mainly induced by reactive oxygen species (ROS), such as the superoxide anion radical (O2 −) and hydrogen peroxide (H2O2). However, in Escherichia coli (E. coli), ROS are eliminated by enzymes such as superoxide dismutase and catalase, which are coded by sodAB and katEG genes. In this study, to detect mutagens that induce oxidative mutation, a mutant (WP2katEGsodAB) with katEG and sodAB deleted was constructed by gene manipulation of E. coli WP2. H2O2 and menadione sodium bisulfite generated mutation in WP2katEGsodAB but not in WP2. o-Phenylphenol (OPP) and its metabolites (phenylhydroquinone (PHQ) and phenyl-1,4-benzoquinone (PBQ)), which had been shown to be negative in the Ames test but reported to be carcinogenic, induced mutation in WP2katEGsodAB but not in WP2. These results suggest that the new assay may be useful for the detection of oxidative mutagens. [Copyright &y& Elsevier]

Abstract: Efforts have been made to reduce municipal wastewater pollutant discharge and improve river water quality in the Yamato-gawa River basin since 2005, as part of a Social Experiment Programme. The Programme was the first one in Japan to disseminate soft interventions in households, measurements to reduce pollutant discharge, in a large river basin with more than two million population. The soft interventions in households are similar to cleaner production in industrial sector because they are not the wastewater treatment and changing of lifestyles. This paper presents several methods for quantification of the pollutant discharge reduction. Two hypothetical soft intervention combinations were defined, the effects of 16 soft interventions were estimated using their proliferation rates, and estimated pollutant discharge reduction was compared with changes in river water quality during the Programme events. For the first method, environmental accounting housekeeping (EAH) books were applied to estimate a 38–53% reduction in biological oxygen demand (BOD), 26–40% reduction in total nitrogen (TN), and 21–32% reduction in total phosphorus (TP). These estimation results were comparable with the field survey results of approximately 100 person population, which were conducted in the late 1980s. Soft interventions were found to be several times more cost effective than hard interventions, such as development of municipal wastewater treatment and river water purification systems. The BOD discharge reduction effects of soft interventions initiated during Programme events increased from 0.3–2.3% in 2005–2007 to 2.4–4.7% in 2007–2009. The questionnaire surveys found that participants in the Programme events in average newly implemented three or four soft interventions in addition to those already implemented at normal times. [Copyright &y& Elsevier]

In this study, a method for removing water from biosolids that uses dimethyl ether (DME) as an extractant was considered. This study evaluates the applicability of the DME dewatering method to biosolid cakes by using a DME flow-type experimental apparatus. It was found that a high dewatering ratio is clearly achieved by increasing the liquefied DME/biosolid ratio and lowering the liquefied DME linear velocity. As the liquefied DME/biosolid ratio was increased, the carbon content in dewatered biosolid showed a slight decrease and the TOC concentration in separated liquid increased significantly. Finally, the input energy Es to remove 1 kg of water from the biosolid cake, using both the DME dewatering method and the conventional drying method was estimated. The calculation shows that Es for the DME dewatering process is approximately a third of Es for the conventional thermal drying process. [ABSTRACT FROM AUTHOR]

Abstract: Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 μg kg−1 in 54 samples of iron ore and 59.9 μg kg−1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y−1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton−1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions. [Copyright &y& Elsevier]

Calcination is the second step in a washing-calcination-conversion system in which treated municipal solid waste incinerator fly ash and bottom ash can be reused as raw material in the cement industry and can decompose or stabilize hazardous compounds, reduce residue amounts, and alter residue characteristics. In this research, only fly ash is discussed. Chloride reduction is important if treated fly ash is to be reused in cement; however, the relationship between washed fly ash properties and chloride reduction by calcination is not well understood. This study used washed residues of three types of fly ash--raw fly ash (RFA) from the boiler or economizer of an incineration system, fly ash collected in a bag filter injected with calcium hydroxide (Ca(OH)2) for acid removal (CaFA), and fly ash collected in a bag filter injected with sodium bicarbonate (NaHCO3) for acid removal (NaFA)--in calcination experiments with varying temperature (400-1100 °C) and atmosphere (100% nitrogen [N2] at 25 mL/min or 10% oxygen [O2] [90% N2] at fluxes of 25, 50, and 75 mL/min). From the perspective of chloride reduction, heating to 1000 °C with 1-hr heating time, 1-hr holding time, and an atmosphere of 10% O2/90% N2 was most suitable for calcination. Under these conditions, chloride levels were reduced by 91, 52, and 96%in washed residues of RFA, CaFA, and NaFA, respectively. Among the washed residues, the weight of the washed residue of NaFA decreased the most. [ABSTRACT FROM AUTHOR]

This article describes the dewatering of sewage sludge using liquefied dimethyl ether (DME), which clarified the effect of sludge type and its particle size. Changes in the heating value of the dewatered sludge were also examined. In addition, the change in dewaterability upon reuse of the liquefied DME was investigated experimentally. Regardless of the nature of the sludge, its dewatering behavior was similar. The amount of dewatered water could be increased by decreasing the diameter of the sludge cake. Complete drying of the sludge cake via DME dewatering resulted in retention of approximately 96% of the heating value (17.7 MJ/kg-sludge) of the original sludge cake dry base (18.4 MJ/kg db). The DME could be recovered after extraction, and reuse experiments showed that liquefied DME dewatering performance was unchanged after five reuses. [ABSTRACT FROM AUTHOR]

Abstract: Chloride in fly ash from municipal solid waste incinerators (MSWIs) is one of the obstructive substances in recycling fly ash as building materials. As a result, we have to understand the behavior of chlorides in recycling process, such as washing. In this study, we used X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) to study the chloride behavior in washed residue of raw fly ash (RFA). We found that a combination of XRD and XANES, which is to use XRD to identify the situation of some compounds first and then process XANES data, was an effective way to explain the chlorides behavior in washing process. Approximately 15% of the chlorine in RFA was in the form of NaCl, 10% was in the form of KCl, 51% was CaCl2, and the remainder was in the form of Friedel''s salt. In washing experiments not only the mole percentage but also the amount of soluble chlorides including NaCl, KCl and CaCl2 decreases quickly with the increase of liquid to solid (L/S) ratio or washing frequency. However, those of insoluble chlorides decrease slower. Moreover, Friedel''s salt and its related compound (11CaO·7Al2O3·CaCl2) were reliable standards for the insoluble chlorides in RFA, which are strongly related to CaCl2. Washing of RFA promoted the release of insoluble chlorides, most of which were in the form of CaCl2. [Copyright &y& Elsevier]

Abstract: We investigated whether polychlorinated biphenyls (PCBs) and water could be simultaneously removed from river sediment by solvent extraction using liquefied dimethyl ether (DME) as the extractant. DME exists in a gaseous state at normal temperature and pressure and can dissolve organic substances and some amount of water; therefore, liquefied DME under moderate pressure (0.6–0.8MPa) at room temperature can be effectively used to extract PCBs and water from contaminated sediment, and it can be recovered from the extract and reused easily. First, we evaluated the PCB and water extraction characteristics of DME from contaminated sediment. We found that 99% of PCBs and 97% of water were simultaneously extracted from the sediment using liquefied DME at an extraction time of 4320s and a liquefied DME/sediment ratio of 60mLg−1. The extraction rate of PCBs and water was expressed in terms of a pseudo-first-order reaction rate. Second, we estimated the amount of DME that was recovered after extraction. We found that 91–92% of DME could be recovered. In other words, approximately 5–10% of DME was lost during extraction and recovery. It is necessary to optimize this process in order to recover DME efficiently. The extraction efficiency of the recovered DME is similar to that of the pure DME. From the results, we conclude that solvent extraction using liquefied DME is suitable for extracting PCBs and water from contaminated sediment. [Copyright &y& Elsevier]

In this study, we evaluated the applicability of the dimethyl ether (DME) dewatering method originally developed for high-moisture coal to superabsorbent polymer (SAP) and disposable diapers. It was found that liquefied DME successfully extracts water from SAP and disposable diapers. However, the polypropylene outer film and polyurethane used in diapers tended to dissolve in the liquefied DME and were subsequently released with the water discharged. These compounds are highly viscous, making it difficult to remove them from the drain outlet of the prototype. Therefore, the mechanics of the drain outlet should be considered in future studies. [ABSTRACT FROM AUTHOR]

To efficiently reduce and reuse fly ash from incinerators, we suggest trying a new alkaline reagent to neutralize the acid compounds in discharged gas from incinerators and reuse fly ash as the raw material in the cement industry. Normally the washing process includes a pretreatment method to remove chlorides to comply with the strict standards for cement. We examined chloride behavior in washing experiments by X-ray absorption near edge structure (XANES) and X-ray diffraction (XRD) for two kinds of fly ash: (1) fly ash collected in a bag filter with the injection of calcium hydroxide (Ca(OH)2) for acid gas removal (CaFA), and (2) fly ash collected in a bag filter with the injection of sodium bicarbonate (NaHCO3) for acid gas removal (NaFA). We found that the insoluble chlorides in both CaFA and NaFA combined calcium chloride (CaCl2), with some sodium chloride (NaCl) also possibly combined. Under some conditions, the combined CaCl2 and NaCl were released. In particular, when the liquid/solid ratio was greater than 3 or the washing frequency was doubled, less chlorine, insoluble chlorine, and CaCl2 were left in the residues of NaFA than in the residues of CaFA. As a result, it is desirable to use NaHCO3 as the alkaline reagent instead of Ca(OH)2 in the air pollution control system of incinerators for recycling fly ash as a raw material in the cement industry. [ABSTRACT FROM AUTHOR]

Abstract: Bisphenol A (BPA) is a weakly estrogenic monomer used to produce polymers for food contact and other applications, so there is potential for oral exposure of humans to trace amounts via ingestion. To date, no physiologically based pharmacokinetic (PBPK) model has been located for BPA in pregnant mice with or without fetuses. An estimate by a mathematical model is essential since information on humans is difficult to obtain experimentally. The PBPK model was constructed based on the pharmacokinetic data of our experiment following single oral administration of BPA to pregnant mice. The risk assessment of bisphenol A (BPA) on the development of human offspring is an important issue. There have been limited data on the exposure level of human fetuses to BPA (e.g. BPA concentration in cord blood) and no information is available on the pharmacokinetics of BPA in humans with or without fetuses. In the present study, we developed a physiologically based pharmacokinetic (PBPK) model describing the pharmacokinetics of BPA in a pregnant mouse with the prospect of future extrapolation to humans. The PBPK model was constructed based on the pharmacokinetic data of an experiment we executed on pregnant mice following single oral administration of BPA. The model could describe the rapid transfer of BPA through the placenta to the fetus and the slow disappearance from fetuses. The simulated time courses after three-time repeated oral administrations of BPA by the constructed model fitted well with the experimental data, and the simulation for the 10 times lower dose was also consistent with the experiment. This suggested that the PBPK model for BPA in pregnant mice was successfully verified and is highly promising for extrapolation to humans who are expected to be exposed more chronically to lower doses. [Copyright &y& Elsevier]

The risk assessment of bisphenol A (BPA) on the development of offspring of humans is an important issue. There have been some reports on the fate of BPA in rodents, but information on the BPA level in fetal organs essential for the extrapolation to humans is inadequate. In the present study, we investigated the distribution pattern of 14C-BPA-derived radioactivity in fetal tissues following administration of 10 mg/kg 14C-BPA to the pregnant mice. The radioactivity was rapidly transferred through placenta and distributed to all fetal organs including reproductive organs and brains in a similar level. The concentration declined slowly compared with dams. Analysis of metabolites in fetuses showed that a fraction of BPA was unexpectedly large compared to the maternal blood. There was no clear effect of the fetal position in a uterus to influence the radioactivity concentration in whole fetuses. The dose dependence of pharmacokinetics should be recognized to extrapolate the pharmacokinetic result from animal experiments at high doses to humans at low doses. Similar experiments were conducted with an addition of two doses, 1 and 100 mg/kg, respectively. The pharmacokinetics seemed to be linear between 1 and 10 mg/kg, although at 100 mg/kg BPA was absorbed slowly and the radioactivity concentrations in fetuses were much higher than expected based on the linear dose dependence. Repeated doses were administered to pregnant mice since humans are exposed to BPA chronically. Radioactivity level in most of the fetal tissues on repeated administration was higher than single administration. [ABSTRACT FROM AUTHOR]

We proposed a method for the deodorising and dewatering of biosolids. In the proposed method, liquefied dimethyl ether (DME) was used as an extractant for odorous components and water. We developed a bench-scale experiment to almost completely deodorize and dewater biosolids by using liquefied DME at room temperature. The deodorized and dewatered biosolids have sufficient caloric density and can be used as a carbon neutral fuel. Water Environ, Res., 83, 23 (2011). [ABSTRACT FROM AUTHOR]