As an alternative to chlorination, ozonation is being used for disinfecting water. However this high operation cost is a disadvantage so therefore basic information on determining an appropriate dosage of ozone for disinfection is required. In this study, coliphage Q-beta was used as a model virus and was inactivated by ozone in a batch or a flow-through reactor by adding ozone-absorbing substances and/or radical scavengers. The changes in residual ozone concentration and surviving coliphage concentration were measured. Equations expressing the process were formulated and the effectiveness of the monitoring method by PCR for disinfection performance was also discussed experimentally. As a result, the inactivation of coliphages was expressed as a summation of the direct effect of ozone and the indirect effect of radicals. PCR monitoring was assumed to overestimate the surviving coliphage concentration.

View full abstract

Alkylphenolpolyethoxylates (APEOs) have been widely used as nonionic surfactants in various industrial and commercial products. There are two different degradation pathways of APEO. One is the gradual degradation of AP(n)EO to AP(n-1)EO, to subsequent degradation products, and finally to alkylphenol (AP). The other is through the formation of alkylphenol ethoxy acetic acid (APEC). We examined the quantitation method for these substances related to APEO [NP(1-15)EO, OP(1-10)EO, NP(1-10)EC] by high-performance liquid chromatography/mass spectrometry. Method detection limits (MDL), calculated from the replicate analyses of spiked deionized water, were 0.0018 [NP(4)EO]-0.0095[NP(8)EO] (μg·l^-1), 0.0048[OP(5)EO]-0.0090[OP(7)EO] (μg·l^-1), 0.0038[NP(8)EC]-0.0072[NP(5)EC] (μg·l^-1). The quantitation method that we developed has sufficiently low detection limits and can be applied to the influent and final effluent of a sewage treatment plant.

View full abstract

An effective quantitative method for the evaluation of endocrine-disrupting chemicals based on the secondary sexual characteristics of medaka (Oryzias latipes) using an S-rR strain has been developed in this study. Although the major characteristics of gross morphologies of fish for the detection of the effects of endocrine-disrupting chemicals are GSI (gonadosomatic index) and gonadal morphology, some disadvantages, such as low sensitivity, have been reported. The method we propose here involves the simple counting of the number of nodes in the second ray of the last anal fin. The S-rR strain was exposed to 17β-estradiol (E₂) at three concentrations (16, 32 and 64 ng·l^-1) from the fertilized-egg stage to the 70-day posthatch. At the termination of exposure, the number of nodes as well as the maximum number of small papillary processes on a ray and the number of rays with small papillary processes in the anal fin were determined. We found that the number of the ray nodes would satisfied with the purpose for quantitatively evaluating effects of endocrine-disrupting chemicals. The present study provides a more convenient and cost-effective method based on the secondary sexual characteristics of medaka that may be used for the reliable evaluation of the effects of endocrine disruptors.
^*1 The Node Count Method is a new technique for quantitative evaluation of endocrine-disrupting chemicals based on the secondary sexual characteristics of medaka (Oryzias latipes) strain described in this paper. This technique was developed in the research that the National Institute of Advanced Industrial Science and Technology (AIST) entrusted to Sumika Technoservice Corporation.

View full abstract

The influence of highway runoff on receiving water is considered serious. On the road surface and in side ditches, rubber debris from tires and automobile exhaust emission in the atmosphere and precipitation accumulate. These pollutants are discharged by heavy rainfall to the receiving water. These pollutants contain materials harmful to the human body and the ecosystem. In this study, the authors have investigated the amounts of accumulated pollutants and highway runoff pollutants. The correlation between SS (suspended solid) concentration and benzo(a)pyrene concentration was analyzed, and the mechanisms of highway runoff pollution and accumulation pollution were clarified. Benzo(a)pyrene concentration seemed to correlate with SS concentration. Therefore, the authors have anticipated that benzo(a)pyrene concentration is high in highway runoff and accumulated pollutants based on the runoff and accumulation models of SS. The result obtained using these models almost correspond to the experimental result.

View full abstract

Recently, the effects of endocrine disrupters on human health and ecosystem have been of great concern. In this research, we investigated the fate of endocrine disrupters in the wastewater treatment process. Moreover, we studied how to reduce levels of endocrine disrupters by controlling SRT (solids retention time) which is one of the important factors in the wastewater treatment process. Finally, it was clarified that 17β-estradiol (E2) is decomposed by activated sludge, and nonylphenol is adsorbed and removed by activated sludge. Moreover, in the case of a longer SRT process, E2 is decomposed in the earlier stage of the process, and it is estimated that about 10 days or 12.5 days is required for microorganisms that decompose E2 or E1 to grow. In the case of a shorter SRT, E2 and estorone (E1) levels tended to increase in aerobic tanks. One of the reasons is that removal rates of the E2 conjugate, E2 and E1 were different in each SRT, that is, the E2 conjugate was decomposed more rapidly than E2 and E1 so E2 and E1 were increased.

View full abstract

Colony size is an important factor in developing algal blooms. For the purpose of determining the relationship between colony size and cell density for growth strategy, the growth monitoring of bloom-forming cyanobacteria was monitered the Kitayamada Fishery Harbor in the southern basin of Lake Biwa from July to September 1999, with colony size measured using an image analysis system. The cell densities of Microcystis aeruginosa and Microcystis wesenbergii (Cyanobacteria) increased gradually during this period and surface-water blooms developed at the end of August and at the end of September, separated by a period of no growth in early September. However seasonal changes in mean colony size did not occur in concordance with seasonal changes in cell density. The percentage of large colonies (>300μm) increased in early September, when the mean diameters of the colonies of both species reached their after peaks. These results suggest than Microcystis colony size is likely to be the largest during a quiescent stage of their life cycle after a period of increased cell density.

View full abstract