The start-up and treatment ability of a stirred tank anammox reactor (STAR) using PVA gel as biomass carrier were systematically investigated. PVA gels, as a new kind of biomass carrier, exhibited satisfactory treatment ability. Experimental results showed that a maximum nitrogen removal rate of 4.3kg/m³/d was achieved after 305 days of operation. Different operational strategy indicated that there was limited effect of influent concentration on the treatment ability of the anammox sludge, while the change of HRT has a positive effect on the treatment ability of the anammox sludge. The effluent SS level was relatively low, with an average of about 10mg/L, which indicated the slight loss of anammox sludge. Stereo microscope and SEM observation showed that anammox sludge gradually and firmly attached on the surface of the PVA gels, showing the effectiveness of PVA gel as the biomass carrier of anammox sludge. DNA analysis showed anammox bacterium KSU-1 was dominant in the annammox reactor, further confirming the effectiveness of using PVA gel bead to culture anammox bacteria.

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Geobacter species are dissimilatory iron-reducing deltaproteobacteria (DIRD) that have various capabilities for bioremediation and microbial fuel cells, including, but not limited to, dissimilatory iron reduction. Furthermore, novel DIRD have been isolated and studied worldwide. However, these bacteria have not been isolated in Japan. In this study, we attempted to develop a rapid detection method of DIRD by real-time PCR and melting curve analysis to make DIRD detection more efficient. Sediments samples were collected from four sites of the Tomoe River and one of its tributaries in the urban area of Shizuoka City, Japan. When sediments from all the sites were incubated in a ferrihydrite-enriched medium, the medium turned black after 14 days of incubation and showed a magnetic response, indicating the presence of DIRD. Denaturing gradient gel electrophoresis profiles of the samples after incubation revealed that species closely related to Geobacter sulfurreducens PCA exist in all the samples. Furthermore, we found a species closely related to Desulfuromonas alkaliphilus Z-0531 in the midstream sample of the Tomoe River. Consequently, we succeeded in detecting DIRD in all the samples by melting curve analysis without ferrihydrite-enriched cultures.

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The purpose of this study is to reveal the effects of power saving via aeration time control on the characteristics of treatment water quality and biota in an activated sludge process of sewage treatment. For this purpose, an anaerobic-aerobic cyclic activated sludge process with different power-off times, i.e. non-aeration time intervals, and sludge circulation ratios were studied comparatively. As a result, when the power-off interval was 6 hr･day^-1, the BOD concentration in the effluent was comparable to that in the control, which was obtained via operation with standard full time aeration, whereas when the power-off interval was 12 hr･day^-1, the BOD was higher compared to the control. The NH₄-N concentration increased and the NO_X-N decreased when the power-off interval increased. The T-P for both power-off intervals were lower compared to the control. These results indicated that the BOD consumption and nitrification reaction were inhibited when the indicated DO was less than 1 mg･l^-1. When the power-off interval was changed from 12 hr･day^-1 to 6 hr･day^-1, the total non-aeration time was the same at 12 hr･day^-1, and high sludge circulation ratios were maintained, the wastewater treatment performance was as good as that of the control. In all operations, the biota characteristics were not affected by the power-off conditions. The results suggested that sewage treatment with a good treatment water quality could be achieved successfully by selecting appropriate operating conditions with half the power normally supplied to sewage treatment.

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