At Inachuo sanitation center-facility, extremly effective aerobic digestion treatment of night soil has been accomplished. In order to analyze dominant bacteria and to elucidate the biochemical characteristics of them, bacteria were isolated from the activated sludge of aerobic digestion tanks. The number of colonies was 5 ×10⁷- 5 × 10¹⁰ml^-1, and 92-98% of them was of Bacillus spp. 32 strains of Bacillus spp., 1 strain of Nocardioform bacterium and 2 strains of gram negative bacteria were isolated. Additionally, 2 strains of yeasts were isolated. Bacillus spp. isolated were classified into 2 types. One solubilized starch, but not cooked meat, and the other did cooked meat, but not starch. Some strains of Bacillus spp. assimilated soybean oil. All strains decomposed hydrogen sulfide and assimilated diethyl amine. Some strains used ammonia as the source of nitrogen, and showed denitrification-ability. Decomposition of night soil was accomplished using some strains of Bacillus spp. The mechanisms of dominant growth of Bacillus spp. and the relationship of Bacillus spp. with buking were discussed.

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Differential equations were developed to simulate the dynamics of a batch culture microcosm that was made up of bacteria Pseudomonas putida, protozoa Cyclidium glaucoma and green alga Chlorella vulgaris.
Two different types of equation were examined. One was the equation taking account of metabolites of microbs and the other was the equation not taking account of them. The results of the simulation were compared with the empirical data obtained from subsystems substrate-one species and substrate-two species, and from the microcosm.
It was shown that the differential equations with the variable metabolites and the variable of non-predated bacteria by protozoa corresponded better with empirical data than the equations without. Therefore, it was suggested that promotion and inhibition of microbial growth by each metabolite, and the existence of non-predated bacteria by protozoa were important for the dynamics of a batch culture microcosm.

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A mathematical model for evaluating the effects of environmental condition. i.e., light condition, flow rate, water temperature, stream depth, etc., on the changes in water quality in a channel was constructed. Structure and parameter values in the model were determined from the results of experiments using artificial channels and the results of batch experiments using artificial substrata attached with river-bed biofilm.
Calculation results by the model showed the concentration of dissolved oxygen (DO) should be maintained high (about more than 4 mg·l^-1) for the removal of pollutants, i.e., total organic carbon (TOC), total nitrogen (T-N), and total phosphorus (T-P). High temperature was desirable for T-N removal. On the contrary, low temperature was desirable for T-P removal because high temperature increased DO consumption rate with decomposition of organic matter and increased release rate of phosphorous from river-bed biofilm. Temperature was not an influential factor for TOC removal. Increase in the area of support media for attachment of biofilm would not improve the removal of T-N and T-P because DO concentration was tended to become low with the consumption of DO by increased biofilm area.

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An anaerobic fluidized pellet bed bioreactor (AFPB bioreactor) system combined with a contact aerator can effectively remove SS, COD, nitrogen and phosphorus. The formation mechanism of sludge pellets and the features of nitrification-denitrification in this system were investigated. By adding polymerized aluminum chloride and weak anionic polymer, the sludge pellets with high density were formed in the AFPB bioreactor above 15°C of water temperature and possessed a high microbial activity such as denitrification and sulfate reduction. A filamentous bacteria was greatly responsible for the formation of this kind of sludge pellets. The filamentous bacteria was identified as a microaerobe, Beggiatoa sp. based on the morphological and physiological features. As most of the SS and COD components were removed as sludge pellets in the AFPB bioreactor, the loading of these substances to the contact aerator was remarkably decreased. Consequently, the solid retention time of the contact aerator, apporoximately 20 day, was long enough to sustain the sufficient growth of nitrifies. Therefore, the system proposed in this study, had a high nitrifying and denitrifying ability in the wide range of temperature.

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Pretreatments in extraction of Thiuram from environmental water with polystyrene-gel minicartridge were studied.
Thiuram was added to river water and pond water after the pretreatment of water samples with salts, EDTA, etc. An addition of EDTA and NaCl was the most effective pretreatment.
Addition of 1.0g of EDTA and 60g of NaCl per 200ml of water samples resulted in high recovery compared to no pretreatment in both extractions just after the addition and after stored at 4°C for 1 to 6 days. While the recovery of Asulam decreased upon storage with the pretreatment.

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