Publications by authors named "Nao Ishikawa"

6 Publications

  • Page 1 of 1

Degradation of the endocrine-disrupting 4-nonylphenol by ferrate(VI): biodegradability and toxicity evaluation.

Environ Sci Pollut Res Int 2022 Mar 27;29(13):18882-18890. Epub 2021 Oct 27.

Course of Civil and Environmental Engineering, Department of System Innovation Engineering, Faculty of Science and Engineering, Iwate University, Ueda 4-3-5, Morioka, 020-8551, Japan.

4-Nonylphenol (4-NP) is an endocrine-disrupting and persistent chemical and is partially degraded in conventional wastewater treatment processes. Ferrate(VI) can be used as an environment-friendly oxidizing agent to mediate 4-NP degradation. Thus, this paper evaluates the biodegradability of 4-NP and its degradation products after the addition of ferrate(VI). The biodegradability was examined using NP labeled with C as a tracer and activated sludge microorganisms as an inoculum. The addition of ferrate(VI) to the 4-NP solution spiked with the tracer resulted in no remarkable decrease in the concentration of C, indicating incomplete mineralization of 4-NP and formation of degradation products. The degradation products from 4-NP with Fe(VI) were estimated based on mass spectra, which detected a unique peak at m/z 223 at low intensity. Four hydrogen atoms might have been added to 4-NP by degradation with Fe(VI). In addition, the effect of ferrate(VI) concentration on the estrogenic activity of 4-NP in an aqueous solution was investigated using a yeast bioassay. The results show that estrogenic activity was significantly decreased at a mass ratio of Fe(VI) to 4-NP greater than or equal to 2.5.
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http://dx.doi.org/10.1007/s11356-021-17167-1DOI Listing
March 2022

Removal of nonylphenol and nonylphenol monoethoxylate from water and anaerobically digested sewage sludge by Ferrate(VI).

Chemosphere 2019 Dec 18;236:124399. Epub 2019 Jul 18.

Course of Civil and Environmental Engineering, Department of System Innovation Engineering, Faculty of Science and Engineering, Iwate University, Morioka, 020-8551, Japan.

Nonylphenol (NP) and nonylphenol monoethoxylate (NP1EO) have toxic and persistent characteristics, and are incompletely degraded in conventional wastewater treatment processes. These compounds are present in sewage sludge that can be reused as fertilizers or soil conditioners. Accordingly, NP and NP1EO should be properly removed before being discharged in the environment. In this study, potassium ferrate (KFeO) containing hexavalent iron (Fe(VI)) was used as an environment-friendly oxidizing agent to mediate NP and NP1EO degradation. The aim of this study was to investigate the effects of pH and Fe(VI) dosage on the degradation of NP and NP1EO in water and anaerobically digested sewage sludge samples. In water samples, under conditions examined in this study, maximum removal efficiencies for NP and NP1EO were 98% and 92%, respectively. For digested sewage sludge samples, the maximum removal efficiencies of NP and NP1EO were 58% and 96%, respectively. The results demonstrated that Fe(VI) can potentially degrade NP and NP1EO in water and digested sewage sludge samples. However, organic matter as a matrix in the sludge sample would inhibit the degradation of NP and NP1EO by Fe(VI). The pH values before and after adding KFeO to the samples had an obvious influence on the removal of NP and NP1EO.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124399DOI Listing
December 2019

Determination of tylosin excretion from sheep to assess tylosin spread to agricultural fields by manure application.

Sci Total Environ 2018 Aug 28;633:399-404. Epub 2018 Mar 28.

Faculty of Science and Engineering, Iwate University, Ueda 4-3-5, Morioka, Iwate 020-8551, Japan.

Antibiotics administered to livestock are partly excreted with urine and feces. As livestock excrement is used as manure on agricultural fields, soil may be contaminated by excreted antibiotics, potentially resulting in the development of antibiotic-resistant bacteria. Therefore, it is necessary to determine the amount of antibiotic administered to livestock that could spread to agricultural fields through manure application. This study reveals the excretion ratio of tylosin from sheep. After developing an analysis procedure for tylosin in urine and feces from sheep, a tylosin excretion study was performed with two sheep. Tylosin was excreted in urine and feces for four days, after which its concentrations dropped below the limits of quantification (urine: 0.5μg/kg, feces: 2.4μg/kg). The total excretion ratio was 11% on average. The results of our study can provide useful knowledge for treating excrement in order to prevent the spread of antibiotics to agricultural fields through manure application.
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http://dx.doi.org/10.1016/j.scitotenv.2018.03.216DOI Listing
August 2018

Biological oxidation of arsenite in synthetic groundwater using immobilised bacteria.

Water Res 2012 Oct 20;46(15):4825-31. Epub 2012 Jun 20.

Department of Frontier Materials and Function Engineering, Iwate University, Ueda 4-3-5, Morioka 020-8551, Japan.

Biological oxidation of arsenite (As(III)) in synthetic groundwater was examined by using arsenite oxidising bacteria (AOB) isolated from an activated sludge. The phylogenetic analysis indicated that the isolated AOB was closely related to Ensifer adhaerens. Batch experiments showed that for an As(III) oxidation with the isolated AOB the optimum ratio of nitrogen source (NH₄-N) concentration to As(III) concentration was 0.5 (52 mg/L-110 mg/L) and the isolated AOB preferred pH values ranging from 6 to 8, and water temperatures greater than 20 °C. Further continuous experiments were conducted using a bioreactor with immobilised AOB. With an initial As(III) concentration of 1 mg/L at a hydraulic retention time (HRT) of 1 h, an As(III) oxidation rate was around 1 × 10⁻⁹ μg/cell/min and an As(III) oxidation efficiency of 92% was achieved. Although the maximum oxidation rate measured at an HRT of 0.5 h was 2.1 × 10⁻⁹ μg/cell/min, the oxidation efficiency decreased to 87%. These results advocate that a biological process involving immobilised AOB may be useful as an economical and environmentally friendly pre-treatment step for As removal from groundwater.
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http://dx.doi.org/10.1016/j.watres.2012.06.013DOI Listing
October 2012

Iodide sorption and partitioning in solid, liquid and gas phases in soil samples collected from Japanese paddy fields.

Radiat Prot Dosimetry 2011 Jul 13;146(1-3):155-8. Epub 2011 Apr 13.

Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.

Sorption kinetics of iodide (I(-)), which is one of the major inorganic chemical forms of iodine in soil environments, were studied under four sets of experimental conditions characterised by temperature or biological activity. We compared partitioning ratios in solid, liquid and gas phases in soils as well as soil-soil solution distribution coefficients (K(d)s) at two different temperatures 4 and 23 °C, for 63 paddy soil samples collected throughout Japan. Interestingly, (125)I emission from soil was observed; the partitioning ratios in gas phase ranged from 0 to 27 % at 4 °C and from 0 to 42 % at 23 °C. In addition, the authors found that K(d) values at 23 °C had good correlation with pH though there was no correlation between K(d) values at 4 °C and pH because of the difference in biological activity.
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http://dx.doi.org/10.1093/rpd/ncr126DOI Listing
July 2011

Estimation of soil-soil solution distribution coefficient of radiostrontium using soil properties.

Appl Radiat Isot 2009 Feb 18;67(2):319-23. Epub 2008 Oct 18.

Office of Biospheric Assessment for Waste Disposal, National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555, Japan.

We propose a new approach for estimation of soil-soil solution distribution coefficient (K(d)) of radiostrontium using some selected soil properties. We used 142 Japanese agricultural soil samples (35 Andosol, 25 Cambisol, 77 Fluvisol, and 5 others) for which Sr-K(d) values had been determined by a batch sorption test and listed in our database. Spearman's rank correlation test was carried out to investigate correlations between Sr-K(d) values and soil properties. Electrical conductivity and water soluble Ca had good correlations with Sr-K(d) values for all soil groups. Then, we found a high correlation between the ratio of exchangeable Ca to Ca concentration in water soluble fraction and Sr-K(d) values with correlation coefficient R=0.72. This pointed us toward a relatively easy way to estimate Sr-K(d) values.
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http://dx.doi.org/10.1016/j.apradiso.2008.09.017DOI Listing
February 2009
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