The bacterial community structure in composting toilet reactors was analyzed using three molecular biological techniques (PCR-DGGE, T-RFLP and cloning). Investigation was conducted for about six months at two trial sites in Japan. The main points of difference between the two sites are in the frequency of use air temperature (Site1: 5-6 times·d^-1, 14.9°C, Site2: 30 times·d^-1, 23.4°C). The DGGE band pattern indicated that the bacterial community profiles changed immediately after the start of the operation and did not reach a stable phase. Sequencing of the dominant DGGE band and clones revealed that the members of the community consisted of Bacteroidetes-related, Proteobacteria-related and other uncultured bacteria in the Site1 reactor. In contrast, Bacillus-related bacteria were detected from dominant DGGE bands from samples in Site2. This difference resulted from the difference in temperature inside the reactors. Some sequences from Site2 samples were also reported from other biodegradation processes under aerobic and thermophilic conditions. The bacterial community of the Site1 profile also had some similarity to other composting processes. Further investigation into the details of the bacterial community and the metabolic characteristics is needed to improve composting toilet operation.

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Three-dimensional excitation-emission matrix (EEM) fluorescence spectra were used to evaluate and compare the characteristics of dissolved organic matter (DOM) in lake and river waters as well as effluent from several sewage treatment plants. Our comparisons of the EEMs indicated a substantial difference in the peak profiles among the samples. For example, five peaks (i.e. Ex/Em = 225/280, Ex/Em = 225/340, Ex/Em = 240/420, Ex/Em = 340/430, and Ex/Em = 480/520nm) were observed on the EEM of the sewage treatment plant effluent, but only two peaks (i.e. Ex/Em = 240/420 and Ex/Em = 340/430nm) were observed in the case of the lake and river waters. Furthermore, one of the peaks (i.e. Ex/Em = 340/430), which has been used as an indicator of the humic-like groups of DOM, was actually found in the EEMs of both humic and non-humic fractions prepared by the XAD-8 resin fractionation method. The non-humic fraction consistently accounted for 30-50% of the peak intensity of the DOM . This result suggests that the peak at Ex/Em = 340/430 is not appropriate as an indicator of humic-like groups in DOM.

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We compared the denitrification rates and bacterial denitrification genes (nirK and nirS) between denitrification processes using NO₂^- and NO₃^-. We operated a sequencing batch reactor (SBR) for denitrification using activated sludge. The SBR was first fed with NO₃^- (Run 1), and the electron acceptor was then changed to NO₂^- (Run 2). Methanol was fed as the major electron donor through out the operational period (64 days). Denitrification rates (mg-N · g-MLSS^-1 · h^-1) were measured at regular intervals. Results showed that the maximum denitrification rates were more than 40 mg-N · g-MLSS^-1 · h^-1 irrespective of electron acceptor type. However, it takes 12 days to reach the maximum denitrification rate after changing the electron acceptor to NO₂^-. The results of the cloning analysis of nirK and nirS implied that the lag time was attributable to bacterial population shifts, because the nirK and nirS detected at Run 1 were phylogenetically different from those at Run 2. However, the changes in the total copy numbers of nirK or nirS could not explain the changes in the denitrifying rates.

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The inputs and outputs of manganese flux in a tea field are estimated. The total input of manganese into the field is estimated at 12 kg · ha^-1 · y^-1, which is due to applied manure and fallen or cut leaves and branches. The total output is estimated at 49 kg · ha^-1 · y^-1, which is due to harvest, surface runoff and interflow (spring water), infiltration and absorption. As a result, the amount of manganese taken out of the field is estimated at 37 kg · ha^-1 · y^-1, most of which is included in surface runoff and interflow. The manganese content of the soil in the tea field is 850 μg · (g-dry)^-1. Assuming that the density of the soil and the depth of soil are 2.5g · cm^-3 and 90 cm, respectively, it is estimated that the total manganese content of the soil in the field is 140 t. The total amount of manganese taken out of the field is estimated at 278 kg · y^-1. This value is 0.20 % of the total manganese content of the soil and does not have a significant effect on the manganese content of the soil.

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