Wastewater from dyeing-industry contains high levels of organic nitrogen deriving from urea. Thus, effective nitrogen removal process is needed to reduce effluent nitrogen concentration below effluent nitrogen standard before discharging effluent to receiving waters. We have developed the novel non-woven support-surrounded cell (SSC) process for the effective and economical nitrogen removal process and acquired a patent with this process. We set up a pilot-scale SSC reactor in the dyeing-industry and continuous nitrification / denitrification treatment experiments were conducted using wastewaters from the dyeing-industry. In case of no pre-aeration treatment before the SSC treatment process using activated sludge, nitrification did not proceed and a lot of paste materials were attached on the surface of non-woven fabrics. Therefore, pre-aeration process with HRT of 12 hours before the SSC treatment process was evaluated. Most oils were degraded from the dyeing-industry wastewaters during pre-aeration process and nitrification and denitrification reactions occurred in SSC reactors. By the combination of pre-aeration process with HRT of 12 hours and the SSC treatment process using activated sludge with HRT of 1.5 days, a total-nitrogen removal efficiency of about 38% was obtained without adding an organic carbon source.

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A cysteine-rich metal binding protein MT (metallothionein) gene (bmtA) and a CPx－ATPase metal transporter gene (bxa1) are induced upon exposure to multiple heavy metal ions in the cyanobacterium Oscillatoria brevis. The SmtB/ArsR family repressor BxmR from O. brevis represses the expression of an operon encoding bmtA and bxmR, and another operon encoding bxa1. In the present study, the expression of bmtA and bxa1 was induced in vivo by 5－15 μM gold (Au) treatment for 1－4 h with a different level in O. brevis cells. In vitro electrophoretic gel mobility shift analysis (EMSA) revealed that the Au treatment promotes a disassembly of BxmR protein from the BxmR－bxmR/bmtA operator (O)/promoter (P) or BxmR－bxa1 O/P complex with a different affinity. Our results indicate that Au treatment can cause a release of BxmR protein in gene-expression level of these genes in O.brevis.

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A nitrification reaction by nitrifying bacteria has remarkably exerted the influence in the measurement method of present BOD according to the design and the operation condition of facilities though the quality of effluent in domestic wastewater treatment facilities has been evaluated by before disinfection in johkasou and after disinfection in public sewerage systems. Moreover, the examination of the influence evaluation of the chlorine disinfection is not necessarily done enough. In this study, we examined the quality of effluent in operating johkasous before and after disinfection for the appropriate and efficient promotion of domestic wastewater measures to protect regional aquatic environments. The investigation was executed for 85 small johkasous which had been installed in the separate houses in prefecture of KANTO area. As a result, the rate of BOD fitting to an expected performance reached 92% after disinfecting 79% whole before disinfected, and the effect of the BOD removal in the disinfection tank was admitted. In the evaluation of the effect of the environmental load-reducing the final effluent on the destination from this, it was showed that it was appropriate intended for the quality of effluent after disinfected, and there were few significant differences concerning the treatment performance with public sewerage systems.

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Simultaneous nitrification and denitrification (SND) with excess sludge reduction were evaluated in an attached growth treatment system consisting of a down-flow anaerobic fermentation (AF) reactor and an aerobic swim-bed (SB) reactor operated as an integrated fixed-film activated sludge (IFAS) process. The two reactors were packed with biomass carriers consisting of different configurations of the same acrylic-fiber material: a net-type carrier biofill® (BL) in the AF reactor and a multi-directional thread-type carrier biofringe® (BF) in the SB reactor. The system was operated continuously under various organic loading rates (OLRs) from 1.5 to 4.5 kg COD m^–3 d^–1 and nitrogen loading rates (NLRs) from 0.1 to 0.3 kg N m^–3 d^–1 using moderately high-strength synthetic wastewater. The AF reactor, located upstream of the SB reactor, provided hydrolysis, fermentation and anaerobic ammonification. During 184 days of operation, stable total nitrogen (TN) removal efficiencies ranging from 85% to 97% were obtained primarily due to SND in the SB reactor when the OLR was higher than 2.7 kg COD m^–3 d^–1. In addition, observed sludge yields for the whole system ranged from 0.13 to 0.17 kg MLSS kg^–1 COD_removed; furthermore, mixed liquor suspended solids (MLSS) were maintained at about 10,000 mg l^–1 in the SB reactor. Exceptionally high COD and TN removal rates of 5.9 kg COD m^–3 d^–1 and 0.43 kg N m^–3 d^–1, respectively, were observed in the SB reactor. These results demonstrated that excess sludge reduction and SND could be achieved concurrently by this combined AF－SB system.

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The flagellate protozoan Monas guttula preys upon the cyanobacterium Microcystis. M. guttula was cultured in suspensions of Microcystis aeruginosa or M. aeruginosa together with the filamentous cyanobacterium Planktothrix agardhii. Monas guttula did not prey upon P. agardhii but the specific growth rate of M. guttula increased 20－30 % with the addition of P. agardhii. The specific growth rate of M. guttula increased by more than 2.5 mg dry weight・l^–1 of P. agardhii. The feeding rate of M. guttula on M. aeruginosa was increased by the addition of P. agardhii, a finding that might be related to promotion of growth of M. guttula.

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Protistan densities were compared in winter flooded and conventional rice paddies. There were significant differences about protistan and cyanobacterial densities in the rice paddies. The mean densities of planktonic microorganisms such as protist and cyanobacteria in winter flooded and conventional rice paddies were 36,700 cells/ml and 13,800 cells/ml respectively. We clarified the densities of microorganisms in the effluent water from rice paddies in May. There were also significant differences about protistan and cyanobacterial densities in the rice paddies. The mean densities of protist and cyanobacteria in winter flooded and conventional rice paddies were 49,000 cells/ml and 18,000 cells/ml respectively. Abundant protistan densities containing in effluent from rice paddy will promote plenty of aquatic animals such as tadpoles, frogs, larva of dragonfly, salamanders, loaches, and so forth. The differences of biodiversities and total biomass appearing in rice paddies were caused by planktonic microorganisms that support bottom of the ecological pyramid in rice paddies.

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