The advanced treatment system for water reclamation consisting of membrane filtration, ozonation, ozone-hydrogen peroxide-based AOP (advanced oxidation process) and BAC (biological activated carbon) process has been investigated through two-year-long pilot-scale experiments (72m³·d^-1). Experimental results showed that the amount of TOC (total organic carbon) removed was increased by the combination of conventional ozonation treatment and ozone-hydrogen peroxide treatment; the optimum ozone dose for ozone-hydrogen peroxide treatment was 50-70%. The optimum operating conditions of this treatment system to achieve our target TOC concentration of 3mg·l^-1 were also determined experimentally: total ozone dose of 30mg·l^-1, dose ratio of hydrogen peroxide to ozone of 0.2-0.5g·g^-1 and ΔO₃/ΔTOC of 17g-O₃·g-TOC^-1. Moreover, various evaluation methods for water quality, such as chemical analyses using Japanese drinking water criteria, genotoxicity test and biological regrowth test, revealed that this advanced treatment system is suitable for water reclamation.

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Two commercial nanofiltration membranes, NTR7410 (low salt rejection) and NTR7250 (medium salt rejection) were used for a basic experiment on the rejection of endocrine disrupters such as 17β estradiol, p-nonylphenol, bisphenol A and their complex solution. A nanofiltration membrane experiment was carried out under the operating condition of low transmembrane pressure of 0.5MPa. For the two nanofiltration membranes used, the rejection factor was high in the case, where pH adjustment of each feed solution was not performed. The p-nonylphenol rejection efficiency of NTR7410 was higher than that of NTR7250. On the basis of the former nanofiltration membrane experimental result, four commercial nanofiltration membranes, NTR7410, NTR7450 (medium salt rejection), NTR7250 and NTR729 (high salt rejection) were used for the rejection of endocrine disrupters contained in biologically treated sewage. The biologically treated sewage concentration of 0.039-0.055μg·l^-1 as 17β estradiol equivalent was reduced to the following concentration by each nanofiltration membrane: 0.026μg·l^-1 (NTR7410), 0.026μg·l^-1 (NTR7450), 0.003μg·l^-1 (NTR7250) and 0.009μg·l^-1 (NTR729). Rejection efficiency of endocrine disrupters from the biologically treated sewage increased in the order of NTR7250, NTR729, NTR7450 and NTR7410. Permeate flux of the nanofiltration membranes increased in the order of NTR7410, NTR7250, NTR7450 and NTR729.

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To clarify the contribution of endocrine-disrupting chemicals (EDCs) to the estrogenicity of environmental water, its XAD-2 resin column-concentrates, as well as steroid hormones, alkylphenols and phytoestrogens were assayed by the yeast two-hybrid system with and without S9mix. Lake water, river water, tap water and sewage treatment water exhibited estrogenicity that was enhanced by S9mix. The strong affinity for the estrogen receptor in yeast was observed with steroid hormones containing the 3-position phenolic and 17-position alcoholic hydroxyl groups, and alkylphenols. Among the estrogens, the magnitude of estrogenicity was in the order of: E₂>E₁>>E₃. The estrogenicity of glucuronide or sulfateconjugated estrogens was less than that of free estrogens. However, the estrogenicity of the conjugates of E₁, E₂ and E₃ was enhanced by S9mix. This suggests that the estrogenicity of environmental water enhanced by the addition of S9mix may be due to the estrogen conjugates in the water. The attenuation of E2's estrogenicity by S9mix was also shown that is predicted to be due to its hydroxylation by P450 induced specifically by phenobarbital. The E₂-conjugate may be decomposed by some hydrolase expressed primarily in rat liver.

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Removal efficiencies of Simazin, Fenitrothion, Napropamid, and tetrachloroethylene, PCE, from synthetic wastewater by the multi-soil-layering, MSL, method were studied. Volcanic ash soil (Kuroboku) was generally more effective than sandy soil (Masa) for removal of pesticides. Fenitrothion could be effectively removed by even sandy soil only or zeolite only. Addition of 2 weight % of activated carbon to an MSL system using volcanic ash soil significantly improved its performance for Simazin, Napropamid and PCE removal. Removal efficiencies of the above-mentioned toxic chemicals from wastewater containing mean concentrations (μg·l^-1) of 350 for Simazin, 800-1300 for Fenitrothion, 2000-3500 for Napropamid, and 140 for PCE were 73-100%, 95-97%, 71-100%, and 95-99%, respectively, at their steady state with the loading rates of 270-400 l·m^-2·day^-1. In terms of PCE removal, an MSL system using sandy soil with the addition of metal iron also showed a high removal efficiency of more than 90%. In this MSL system and that with added activated carbon at the rate of 0.2 weight %, PCE was removed not only by sorption but also by degradation. Chemical degradation by metal iron added to the MSL system and biodegradation of PCE into TCE and cis-1,2DCE seemed to occur simultaneously.

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