Relationship between maximum yield and specific growth rate for algae with a growth inhibitory batch test was investigated. Inhibitory effect of wastewater from coke furnace on growth of two species of freshwater algae Selenastrum capricornutum, Microcystis aeruginosa and seawater algae Skeletonema costatum was observed.
The EC50 values estimated from specific growth rate were approximately 5 percent (wastewater mixed medium ratio) for S. costatum, 28 percent for M. aeruginosa and 45 percent for S. capricornutum However, the EC50 values estimated from maximum yield were 8 percent for S. costatum, 10 percent for M. aeruginosa and 18 percent for, S. capricornutum.
Increase in wastewater mixed medium ratio caused decrease of the specific growth rate and maximum yield. There is no common relationship between the specific growth rate and maximum yield for the three spieces.

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Effect of pH on acidogenic phase in anaerobic digestion of night-soil was investigated using anaerobic chemostat-type reactors at 35±1°C at SRT of 1.0, 2.0, 3.0 and 5.2days. The COD concentration of particulate of night-soil was about 16-20g/l. The hydrolysis of volatile solids (VS) and volatile acid formation were studied over the pH range from 6.00 to 8.25. pH more significantly affected the hydrolysis of volatile solids than volatile acid formation. The optimum pH value for hydrolysis was around 7.0 in the batch experiments and the continuous flow experiments. It was observed that the hydrolysis was inhibited by free volatile acid (VFA) at pH 6.00 and by free ammonia at pH 8.25.

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In order to improve the microbial degradation rate of n-tetradecane by Pseudomonas sp. in enriched sea water, the growth mediums which consisted of various nutrients as nitrogen and phosphorus source were investigated experimentally. It was shown that the seawater medium enriched by NH₄NO₃, K₃PO₄ and yeast extract was most appropriate to degrade n-tetradecane by Pseudomonas sp.
When NH₄NO₃/K₃PO₄ ratio was maintained at 10, the relation between the biodegradation rate of oil, r_m mg-oil l^-1h^-1, and the nutrient concentration, S mg-NH₄NO₃l^-1, was in good agreement with the following equation.
r_m=max·S/K_m+S
where (r_m) _max was the maximum r_m and K_m was the saturate constant. For the initial concentration of oil, 153 mg l^-1, (r_m) _max was determined to be 4.9 mg-oil l^-1h^-1 and K_m was 94 mg-NH₄NO₃ l^-1.
Furthermore rapid degradation of the oil was suggested to be a result of the enhanced growth rate of Pseudomonas sp., hence the increased production of emulsifier in the improved medium.

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[in Japanese]

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