The three-year field investigation in hypertrophic Lake Teganuma and laboratory studies were conducted to evaluate the rates of nitrogen and phosphorus eliminated from the lake water.
T-N concentrations in the lake water decreased gradually from the mouth of the Ohori River entering the lake to the outlet of the lake. T-N concentrations in the surface sediments decreased in the mouths of the Ohori River and the Otsu River and leveled off constant values in the downstream of the lake. T-P concentrations in the lake water and surface sediment in Kaminuma, upperstream of Lake Teganuma, decreased remarkably along the flow of water from the inlet to the outlet and leveled off in Shimonuma, downstream of Lake Teganuma.
A three-year nutrient budget indicated that retention coefficients of nitrogen and phosphorus in lake water defined by Vollenweider were 0.34-0.38 and 0.44-0.56, respectively. Phosphorus eliminated apparently from lake water was shifted to sediment phosphorus particularly in Kaminuma. The horizontal distribution of nitrogen in the surface sediments and the laboratory study on denitrification rate in sediment-water systems suggested that a large portion of loss of nitrogen in lake water was caused by denitrification particularly in the sediment-water interface.

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Sludge from wastewater treatment plant of petrochemical industry was acclimatized to 2-chlorophenol under anaerobic conditions. The sludge could degrade 100 mg·l^-1 of 2-chlorophenol to methane in a day via phenol and benzoate. Addition of unacclimatized activated sludge at appropriate intervals was effective to stabilize the degradation activity.
Optimum temperature for degradation of 2-chlorophenol was 40°C and the optimum pH was 7.5. Of three monochlorophenols, only 2-chlorophenol was degraded. As for dichlorophenols, only the Cl group ortho to phenolic OH was reductively dechlorinated and 3- or 4- chlorophenol was formed from 2,3- or 2,4-dichlorophenol without further degradation. 2,6-Dichlorophenol was degraded to methane completely. Among the trichlorophenols, 2,3,6- and 2,4,6-trichlorophenols were dechlorinated to produce 3- and 4-chlorophenols, respectively.
We also discuss the mechanism of reductive dechlorination by the sludge.

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In order to investigate the decomposition of sedimented organic matter in sewers, screenings were used instead of sediments. Because screenings whose sizes were larger than 2mm contained high amount of organic matter usually accumulated in sewer pipes.
When the activity of sulfate reduction was present and sulfate concentration was high amount, approximately 40% of organic matter in the screenings was decomposed for 10 days, on the other hand, when sulfate reduction was inhibited by 20 mM of sodium molybdate only 10% of organic matter was decomposed for 10 days.
Acetic acid and propionic acid were producted during sulfate reduction. However, no fatty acids were detected when sulfate reduction was inhibited.
These results indicated that sulfate reducing bacteria play an important role not only in the production and decomposition of fatty acids but also in the decomposition of solid organic matter.
The authors suggest that the decomposition of fatty acids by sulfate reducing bacteria has accelerated the fermentative acid production resulting in the dehydrolation of organic matter.

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In ferromagnetic powder supplemented activated sludge method, a procedure for recycling ferromagnetic powder was examined for saving costs and reducing residual ash of sludge incineration. In a “wet recovery method”, ferromagnetic powder supplemented to activated sludge was recovered from waste sludge with an apparatus using plastic magnet. Ninety six % of ferromagnetic powder (magnetite) was able to recycle by this procedure. The ratio of return sludge to waste sludge was 86/14. In a “dry recovery method”, waste sludge was incinerated to obtain residual ash containing ferromagnetic powder for reuse. Ferromagnetism was not lost by sludge incineration at 600-650°C for magnetite and at less than 700°C for Sr-ferrite. No change, practically, was observed on the values of settling volume after 1 or 30 min and COD removal when ferromagnetic powder incinerated was resupplemented into activated sludge.

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