Biomedical subjects

Yasumoto Magara

Publications and source records attributed to Yasumoto Magara.

7 recordsLinked to original sources

PubMed2004

Effects of chlorine on the decrease of estrogenic chemicals.

The effects of chlorination on the elimination of three estrogenic chemicals such as 17beta-estradiol, nonylphenol and bis-phenol A were investigated using yeast two-hybrid assay (YTA), estrogen receptor (ER) competition assay (ER-CA), and high-performance liquid chromatography/mass spectrometry (LC/MS). The results of YTA, ER-CA and the analysis of LC/MS indicated that the estrogenic activity of the above-mentioned three endocrine disruptors were significantly reduced as a result of chlorination. The decrease in estrogenic activity paralleled a decrease in estrogenic chemicals under the influence of free chlorine. One common characteristic of estrogenic chemicals is the presence of a phenolic ring. Considering that a phenolic ring is likely to undergo some sort of transformation in an aqueous chlorination solution, the above-mentioned results may be applied to the rest of the estrogenic chemicals in natural waters.

Benzhydryl Compounds↗

PubMed2003

Comparing polyaluminum chloride and ferric chloride for antimony removal.

Antimony has been one of the contaminants required to be regulated, however, only limited information has been collected to date regarding antimony removal by polyaluminium chloride (PACl) and ferric chloride (FC). Accordingly, the possible use of coagulation by PACl or FC for antimony removal was investigated. Jar tests were used to determine the effects of solution pH, coagulant dosage, and pre-chlorination on the removal of various antimony species. Although high-efficiency antimony removal by aluminum coagulation has been expected because antimony is similar to arsenic in that both antimony and arsenic are a kind of metalloid in group V of the periodic chart, this study indicated: (1) removal density (arsenic or antimony removed per mg coagulant) for antimony by PACl was about one forty-fifth as low as observed for As(V); (2) although the removal of both Sb(III) and Sb(V) by coagulation with FC was much higher than that of PACl, a high coagulant dose of 10.5mg of FeL(-1) at optimal pH of 5.0 was still not sufficient to meet the standard antimony level of 2 microg as SbL(-1) for drinking water when around 6 microg as SbL(-1) were initially present. Consequently, investigation of a more appropriate treatment process is necessary to develop economical Sb reduction; (3) although previous studies concluded that As(V) is more effectively removed than As(III), this study showed that the removal of Sb(III) by coagulation with FC was much more pronounced than that of Sb(V); (4) oxidation of Sb(III) with chlorine decreased the ability of FC to remove antimony. Accordingly, natural water containing Sb(III) under anoxic condition should be coagulated without pre-oxidation.

Aluminum Hydroxide↗

PubMed2003

Rapid and economical indicator for evaluating arsenic removal with minimum aluminum residual during coagulation process.

Detection of various types of contaminants in water treatment plant by sophisticated analytical methods such as inductively coupled plasma/mass spectrometry and gas chromatography/mass spectrometry requires hours to days to provide the results. Because naturally occurring ultraviolet (UV) active compounds are commonly present in almost all source waters and can be rapidly monitored by UV absorbance at 260 nm (E260), the extent of correlation between the removal efficiency of E260 and the removal efficiency of As(V) with minimum soluble residual Al by coagulation process was investigated. Percentage removals for E260 were well correlated to those of As(V). When sufficient alum or polyaluminum chloride (PACl) was added for 60-65% removal of E260, 90-95% removal of As(V) was achieved with minimum soluble residual Al regardless of the initial level of turbidity, E260, and As(V). As E260 analysis is precisely available even by an unskilled plant operator in a few minutes, E260 removal efficiency appears to be the promising economical indicator for monitoring the effectiveness of the coagulation process for the removal of contaminants with minimum residual Al.

Aluminum↗

PubMed2003

Removal of organic pollutants and metabolic adaptation of microorganisms by micro-aeration.

Aerobic systems are high rate processes for wastewater treatment, but they consume much power for aeration. Several low-cost anaerobic systems have been developed for mid- and low-income countries. The removal efficiencies of nutrients, particulate matter, and pathogens are not satisfactory for the anaerobic systems. Micro-aeration is a type of low-cost aerobic application which enhances oxygen transfer through water surface. Trickling was found the most efficient method of micro-aeration and batch experiments were performed to evaluate the effectiveness. When soluble organic carbon was removed, ORP7 (redox potential rectified to pH at 7) were around -120 or +260 mV. When soluble organic carbon increased due to organic overload, ORP7 was around +30 mV. At +30 mV, carbon fraction of biomass increased to 0.54 (higher than average value of 0.46). It was presumable that the ORP7 of -120, +260, and +30 mV were anaerobic, aerobic, and internal storage mode, respectively. Maximum reaction rate of aerobic condition was four times as high as that of anaerobic condition. At internal storage mode, the rate was halved from aerobic mode. It is concluded that microorganisms adapt the metabolic systems to conform to the redox environment, which can be evaluated by ORP. Organic overload results metabolic shift to internal storage mode which retards mineralization of organic matter.

Bacteria, Aerobic↗

PubMed2002

Fish test for endocrine-disruption and estimation of water quality of Japanese rivers.

The LC50 values (72 h) of 17beta-estradiol (E2), p-nonylphenol (NP) and bis-phenol-A (BPA) to adult male and female medaka were 3.5 and 3.5, 0.85 and 0.87, and 6.8 and 8.3 mg L(-1), respectively; the LC50 values to embryos were 0.46, 0.13 and 5.1 mg L(-1), respectively. The IC50 values for inhibition to egg hatching were 0.47, 0.85 and 9.0 mg L(-1), respectively. These values were much higher than concentrations detected in river water in Japan and the chemicals were considered to have no lethal effect on the fish in an aquatic environment. Mature male medaka was continuously exposed to 0.005, 0.05 or 1.0 microg L(-1) of E2, or to 0.1, 10 or 100 microg L(-1) of NP or BPA. Female specific proteins (FSP) were induced in the blood of male medaka that were exposed for 5 weeks to E2 higher than 0.005 microg L(-1), NP higher than 0.1 microg L(-1), or BPA higher than 10 microg L(-1). Based on these FSP inducible concentrations and reported concentrations of E2, NP and BPA in Japanese river water, some river water contaminated by E2 or NP could be estimated as the FSP inducible in male medaka.

Air Pollutants, Occupational↗

PubMed2002

Performance of nanofiltration for arsenic removal.

Performance of rapid sand filtration inter-chlorination system was compared with nanofiltration (NF) to reduce the arsenic health risk of drinking water. It was found that rapid sand filtration with inter-chlorination is not effective in removing arsenic. If total arsenic concentration in raw water is below 50 microg/L regardless of the turbidity of raw water, arsenic can be removed below WHO guideline value of 10 microg/L by conventional coagulation (polyaluminum chloride dosage is about 1.5 mg Al/L). However, if the raw water arsenic concentration exceeds 50 microg/L, more coagulant dosage or enhanced coagulation is needed. To adopt optimum coagulant dosage for arsenic removal, it needs to monitor raw water arsenic concentration, but it is difficult because arsenic measurement is time consuming. In addition, if raw water contains As(III), it is difficult for rapid sand filtration inter-chlorination system to meet an arsenic maximum contaminant level of 2 microg/L, which would achieve reduction of cancer risk below 10(-4). On the other hand, the NF membrane (NaCl rejection 99.6%) could remove over 95% of As(V) under relatively low-applied pressure (< 1.1 MPa). Furthermore, more than 75% of As(III) could be removed using this membrane without any chemical additives, while trivalent arsenic could not be removed by rapid sand filtration system without pre-oxidation of As(III) to As(V). Because both As(V) and As(III) removals by NF membranes were not affected by source water composition, it is suggested that NF membrane can be used in any types of waters.

Arsenic↗

PubMed2002

Removal efficiency and homologue patterns of dioxins in drinking water treatment.

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) analyses in raw and treated water throughout Japan were implemented to identify the concentration and homologue patterns of dioxins before and after the water treatment process. In 40 surface water and 5 ground water treatment plants, the removal efficiency of dioxins and the influence of extent chlorination on dioxins increase in drinking water were also studied. Raw water and treated water were sampled twice, summer and winter. The mean concentration in raw water and treated water of dioxins was 56.45 pg/L (0.15 pg WHO-TEQ/L) and 4.24 pg/L (0.019 pg WHO-TEQ/L), respectively. Location of water treatment plants not only significantly influenced the concentration level of dioxins but also resulted in different homologue patterns of dioxins. Levels of dioxins in ground water were much less than that of surface water in both raw and treated water. This study shows most dioxin congeners are well removed (87% removal efficiency) by water treatment. However, in some water treatment plants, the level of TeCDFs (pg WHO-TEQ/L) increased as a result of chlorination.

Dioxins↗