The start-up of mesophilic anaerobic digestion from waste activated sludge with internal inoculum was carried out in a laboratory-scale completely mixed reactor. The microbial community shift during the start-up period was monitored by molecular techniques. The self-degradation period, when the digester was operated in batch mode, consists of two characteristic phases, acidogenic (A) phase and methanogenic (M) phase. During the A phase, Volatile Fatty Acid (VFA) accumulation and a low level of methane production were observed. On the other hand, during the M phase, rapid VFA degradation and an increase in methane production were observed. Clone analysis results suggest that after self-degradation, Methanosarcina and Methanoregula were predominant at day 30, while the former was detected at low level (4%) and the latter was not detected at day 0. The population dynamics of the archaeal community were investigated by Real-time PCR. During the transition from A phase to M phase, the digester showed a significant increase by one order in the Methanosarcina rRNA gene. A significant positive correlation between the population of Methanosarcina and methane production rate was observed.

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Soil contamination by toxic anions has become a serious problem, because of their persistence for a longtime and their diffusion into underground water. In this study, the adsorption equilibria for three hazardous anions of As(V), Se(IV), and Cr(VI) were investigated in a wide concentration range for four types of soilunder the condition of coexisting of competitive anions. The adsorption amount of toxic anions was altered by 20∼40 fold depending on the type of soil, Ando soil, Brown Forest soil >> Glay Upland soil> Terrestrial Rego soil. Metal anion adsorption was hindered by coexisting anions, particularly hydroxide ion, and competitive adsorption could be quantitatively expressed using the multiple isotherm equation proposed in this study. From the quantitative investigation analysis, the effect of the concentration change in liquid phase did not depend on the type of soil, but could be approximated by a constant for each anion. On the basis of experimental results, the behavior of the toxic metal anions in contaminated soils could be estimated by examining the adsorption isotherms for the soils and its pH dependence.

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The origin of foulants that causes physically irreversible fouling in pilot-scale membrane bioreactors (MBRs) treating real municipal wastewater was investigated. Utilization-associated products (UAP), biomass-associated products (BAP), and organic matter contained in the raw wastewater could be considered as potential sources of foulants in MBRs. Organic matter contained in the raw wastewater and BAP were characterized to assess their contributions to the evolution of physically irreversible fouling. Fourier transform infrared (FTIR) analysis, fluorescence excitation-emission matrices (EEM), and monosaccharide/amino acid composition analysis were used to characterize the organic matter. The results revealed that the organic matter contained in the raw wastewater was minor among the foulants regardless of the SRT. The characteristics of the foulant of the MBR operated with a long SRT were relatively similar to those of BAP, while no obvious similarity was observed between the characteristics of BAP and that of the foulant in the MBR operated with a short SRT. It was suggested that the contribution of UAP to the physically irreversible fouling increases as the SRT is shortened. The foulant of the MBR operated with a short SRT exhibited a higher specific filtration resistance than that of the MBR operated with long SRT. UAP causes severe physically irreversible fouling and it is important to minimize the accumulation of UAP in the mixed liquor of MBRs.

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A high concentration of polycyclic aromatic hydrocarbons (PAHs) exceeding the guideline value in US was observed in sediments in Nagoya port. The horizontal distribution of the concentrations of PAHs in the sediments was different from that of organic contents, and was affected by point sources and runoff events judging from the concentrations and compositions of PAHs. The concentration of heavier PAHs dissolved in pore water was higher that the estimated from the equilibrium with the concentration in soil. The heavier PAHs were estimated to be released from sediments to seawater because their concentration in pore water was higher than their dissolved concentration in overlying water.

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Vertical profiles of nutrients were obtained at two monitoring stations (F3 and F6) near the center of Tokyo Bay from 1989 to 2004. During this 16-year period, ammonium concentration decreased consistently at all depths of both stations. Nitrate and nitrite concentrations also decreased significantly at most depths of the inner-side station (F3), whereas only nitrite concentration decreased significantly in surface layers at the mouth-side station (F6). Phosphate and silicate concentrations decreased significantly in the surface waters of both stations. The water-column integrated ammonium concentrations decreased significantly at both F3 and F6, and so did the integrated nitrate and nitrite concentrations at F3. Since the water-column integrated chlorophyll a concentration decreased as well, enhanced nutrient consumption due to an increase in primary production is not the reason for the decrease in nutrient concentrations. The decrease likely reflects the reduced load of nutrients in the bay.

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Cryptosporidium is a protozoan that causes gastrointestinal disease and is resistant to chlorine disinfection. The method of extracting Cryptosporidium DNA from the hard outer shell, called an oocyst, of Cryptosporidium at a high yield is complicated. Generally, the DNA is extracted using proteinase K in a lysis buffer containing sodium dodecyl sulfate (SDS). However, SDS needs to be removed for PCR, because it is one of the strong inhibitors of PCR. We investigated a simple method for suppressing PCR inhibition with nonionic surfactants for the detection of C. parvum DNA. The primer set for real-time PCR was designed from the polythreonine gene of C. parvum. PCR was inhibited by 0.01% of SDS or Sodium dodecyl benzene sulfonate (SDBS), but the inhibition was reversed with the addition of 0.5% Tween 20. Subsequently, we applied this suppression method to C. parvum DNA detection, and succeeded in detecting DNA from 10 oocysts by PCR in the presence of 0.01% SDS or SDBS.

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