Anaerobic degradation of phenol and sodium benzoate was examined at 37°C under different gas atmospheres or in the presence of various inhibitors. In the degradation of phenol, benzoate was formed significantly under the H₂/CO₂ atmosphere.
Anaerobic degradation intermediates of phenol and benzoate were examined under the nitrogen atmosphere in the presence of 2-bromoethanesulfonate, chloroform and molybdate.Benzoate, propionate, acetate and hydrogen were detected in the degradation of phenol, but cyclohexanol and cyclohexanone were not detected. Cyclohexane carboxylate, propionate, acetate and hydrogen were observed as degradation intermediates of benzoate.
In the phenol acclimated sludges, phenol was degraded via benzoate even in the absence of hydrogen and carbon dioxide in the gas phase ; thermodynamic calculation of free energy changes revealed that the reductive carboxylation of phenol to benzoate proceeds even under low hydrogen pressures.
The phenol degradation consortia were sensitive both to the inhibitors and the change in sludge concentration due to the addition of fresh media, while the benzoate degradation consortia was tolerant to these environmental changes. Addition of sludge fluid was effective to increase the degradation rate of phenol.

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In this paper, characteristics of solid-liquid separation of raw wastewater with a drum screen and prevention methods against clogging in the screen's slits by bacterial slime or scaly deposit were studied with pilot-scale equipment.
The results are summarized as follows : judging from filtration rate per unit length to the rotating axis of drum screen and clogging in the slits, wedge-wire was the most suitable material for the drum screen. Through the experiment with two brushes to prevent from clogging, in the case of the wedge-wire drum screen with 100 microns' slits, clogging had not occurred for six months without maintenance. Average SS removal ratio and BOD removal ratio were 30% and 22%, respectively. Separated sludge was discharged from the drum screen automatically and the water content of the sludge was at the low levels of 86.5% to 92.5%. Besides, the proposed formulas enabled to calculate the maximum flowrate of the drum screen. The required area and volume of the drum screen were compared with those of the conventional primary sedimentation tank.

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Dose of nutrient microcapsules enhanced microbial degradation of spilled oil on the sea surface have been investigated.
In the up-and-down shaking apparatus modeled on sea surface, four crude oil such as Arabian light, Berri, Murban and Khafji were degraded by a marine bacteria, Pseudomonas sp. On the cultivation for 21 days, their percentages of total oil removal were 1822% in the sea water, which by dose of the nutrient microcapsules they were enhanced to 4356%. The biodegraded crude oil were fractionated by chromatography on a column of activated alumina. In result, the saturated fraction was most degraded (7585%), following by the aromatics (5565%).
On the biodegradation of 5g of crude oil for 21 days, the oil removal was amounted roughly to maximum when 116 mg of the microcapusule per vessel was added 5 times every 4 days. The percentage of oil removal in the cultivation for 7 days (total dosage ; 116 mg) was more than 80% of the total. And when the dosage interval of the microcapsules was more than 7 days, it lowered.

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The effects of influent substrate concentration and high loading rate on characteristics of substrate removal in methanogenic phase of anaerobic two phase digestion were investigated by using anaerobic fluidized bed reactors. Two kinds of substrates were used. The first one was composed of acetic acid and the second one was composed of acetic acid, propionic acid, butyric acid and glucose. Whichever substrate was used, influent substrate concentration affected the retaining characteristics of biomass. In case of using acetic acid substrate, effluent substrate concentration increased as influent substrate concentration increased. Two kinds of substrates were used at loading rate of 30kg-COD·m^-3·d^-1. The one was mixed acid containing glucose, and the other was acetic acid. In both cases, substrate removal efficiencies of the reactors were high. However, the effluent quality of the reactor to which acetic acid was added were unstable.

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