The absorption treatment of copper ions in acidic water solution using rice bran was examined. Rice bran showed a good pH buffer behavior for an acidic aqueous solution of pH=2.0 prepared by the sulfuric acid. Because rice bran contains phosphorus, indicating that the pH buffer action was induced by the phosphate. In addition, Rice bran adsorbed Cu²⁺ at a the considerable quantity. with heat treatment at 350°C for 6h, Cu²⁺ that adsorbed on to the rice bran was converted to CuO. The possibility of the effective material recycling of Cu²⁺ included in the waste acid was indicated.

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An anaerobic aerobic sequencing batch reactor was operated for 185 days using municipal wastewater supplemented with a laundry detergent including LAS and AE to examine the efficiency of acetate uptake and the availability of the surfactants as a potential PHA source of PAOs under exposure to the detergent. Over the experimental period, the phosphate requirement for acetate uptake (+ΔP/-ΔAc ratio) was estimated by an anaerobic batch test with the addition of acetate. Consequently, it was found that the exposure to the detergent deteriorated the acetate uptake efficiency of PAOs. On the other hand, even though the detergent was added as a sole carbon source in the anaerobic batch test, a significant phosphate release was observed. The organic matter originating from the detergent was then divided into acetate and other organics, and their contributions to phosphate release were estimated using activated sludge collected on the 185th day. 60% of the total released phosphate was caused by the uptake of degradation products of LAS except lower fatty acids such as acetate. Comparing the maximum amounts of released phosphate between the two anaerobic batch tests in which acetate and the detergent were used, the latter was beyond the former after the start of the detergent addition. That is, PAOs that can not utilize acetate but can utilize degradation products of LAS contributed to phosphate removal gradually.

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This study was carried out to determine the rates of release of 5 polyphenolic allelochemicals, namely, (+) catechin (CAT), eugeniin (EUG), and ellagic, gallic and pyrogallic acids (EA, GA, PA, respectively), by Myriophyllum spicatum, and their growth inhibition effect on the cyanobacterium Microcystis aeruginosa. The calculated release rates were 0.040 nmol · g-wet^-1 · h^-1, 0.80 nmol · g-wet^-1 · h^-1, 1.7 nmol · g-wet^-1 · h^-1, 0.18 nmol · g-wet^-1 · h^-1, and 0.17 nmol · g-wet^-1 · h^-1 for CAT, EA, EUG, GA, and PA, respectively. Continuous addition of the 5 polyphenols to the cyanobacterial medium demonstrated the growth inhibition of M. aeruginosa, and the observed inhibitory effect suggested that the 5 polyphenols account for the allelopathic effect of M. spicatum on M. aeruginosa by 70% at the maximum. In addition, a comparison of the release rates of the 5 polyphenols and DOC from M. spicatum indicated that about 10% of organic carbon released from M. spicatum was accounted for by these polyphenols.

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Threshold odor number (TON) was measured for samples of effluents from wastewater treatment plants and river water receiving treated wastewater in the Tama and Nomi rivers to identify factors affecting the odor of treated wastewater in river environments. The TONs of the effluents were between 87 and 373. TON decreased with biodegradation and volatilization in a section of the Tama river, although the transfer rate of odor from water to air was much smaller than that of oxygen from air to water. The acetaldehyde concentrations of the effluents were more than the odor threshold concentration, although no clear correlation between acetaldehyde concentration and TON was obtained.

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