A comparative study on the performance of anaerobic filter and anaerobic hybrid reactor was conducted by using glutamate wastewater as a substrate at 37°C. The inhibition effect caused by high Cl^- concentration and the bacterial structure of granule were also investigated in this study. In the anaerobic filter process, over 90% BOD removal efficiency and over 85% COD removal efficiency were obtained under the COD loading rate of below 6.0kg·m^-3·d^-1. On the other hand, over 86% BOD removal efficiency and over 82% COD removal efficiency were maintained by the anaerobic hybrid reactor until the COD loading rate increased as 12.0 kg·m^-3·d^-1. The maximum capacity of COD loading rate of the anaerobic hybrid reactor process was 12.0 kg·m^-3·d^-1 which is 1.5 times of that of the anaerobic filter process. Scanning electron microscopy relealed that the granular sludges from both reactor were multi (three)-layered bacterial structures. The exterior layer and the middle layer consisted predominantly of bacteria cocci, short rods. The third layer formed the internal core of the granules. It consisted of large numbers of Methanothrix-like bacteria. In order to prevent the inhibition effect caused by high Cl^- concentration, it is safety to control the influent concentration of Cl^- to be below 6,250 mg·l^-1.

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Effects of filter media on treatment characteristics and bacterial distribution were investigated by using an anaerobic filter system operated at 20°C. The low strength synthetic wastewater containing cellulose was used as the substrate. The degradation rate of cellulose was improved by the packing of the filter media. The methane gas recovery efficiency was increased from 23% to 56% by packing of the filter media. Because of the production of CH₄ and CO₂ as the result of substrate degradation, the hydraulic characteristics of the fixed bed reactor was similar to that of the completely mixed continuous flow reactor. The bacteria living in the filter zone at the upper part of the reactor were attached to the filter media or were trapped between the filter media, the density of the latter being two times as much as that of the former. Packig of the filter media improved significantly the retention of the methanogenic bacteria and the lipolytic bacteria, but did not improve that of the glucolytic and proteolytic bacteria. It is clear from these result that packing of the filter media improves treatment efficiency of the reactor remarkably when methane production is the rate determining step and when hydraulic retention time is shorter than the generation time of methanogenic bacteria.

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A new plate culture system, designated as GM plate, for isolation and enumeration of bacteria decomposing organic substance in water has been developed. The GM plate was constructed as follows : a glass-fiber filter was placed in a petri dish and soaked with liquid medium containing 2.0g organic substance as carbon source (acetate, glucose, saccharose, raffinose, triacetin, dextrin, veratric acid, glycolate, starch, pectic acid, alginate or sodium carboxymethyl cellulose), 1.53g KNO₃, 1.6g K₂HPO₄, 0.2g KH₂PO₄, 0.1g NaCl, 0.2g MgSO₄·7H₂O, 0.02g CaCl₂·2H₂O, 1.0mg FeSO₄·7H₂O, 1.0mg ZnSO₄·7H₂O and 1.0mg MnSO₄·4-6H₂O per litre, and a membrane filter was attached on the surface of glass-fiber filter. Sample solution was spread over the surface of the membrane filter of GM plate using spiral plating method. Seven days after incubation of the GM plate at 25°C, the colonies on the plate were counted by direct visual inspection. The method was simple in the operation, and released amounts of total organic carbon from the GM plate to the liquid phase were only 5% of that from agar plate.
Although the pollution due to organic substances among water samples from three rivers investigated could not be distinguished by conventional agar plate method (total bacteria at 25 and 35°C and number of coliform groups, fungi and yeast) and physicochemical analysis (atmospheric and water temperature, pH, suspended solid, dissolved oxygen, biochemical oxygen demand, total organic carbon, total nitrogen and total phosphorus), significant differences in bacterial numbers and distributions were seen among three water samples by GM plate method. It seemed that quantity and quality of organic substances in the river influence the bacterial numbers and strains decomposing organic substances.
These results indicated that the GM plate method is sensitive and useful for evaluating organic pollution in river water.

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Field test has been carried out on advanced methods in summer and winter, in combinations with ozonation, activated carbon adsorption, and biological degradation for the purification of surface river water, which was added Geosmin and 2-methylisoborneol (2-MIB) as a supplement. In this paper, we report the results of removing features of the musty odor substances, principal Geosmin and 2-MIB. The outline of results is as follows :
1) In biological treatment which applied only submerged bio filter, the removal ratios of Geosmin and 2-MIB were 34%, and 23% respectively. So, this unit operation didn't seem to be enough for the removal of the musty odor substances.
2) For the more than 80% removal of Geosmin and 2-MIB, ozone additions of 1.5-1.7mg·l^-1 and 1.8-1.9mg·l^-1 were needed respectively.
3) More than 95% of the musty odor substances were removed in combination with ozone and activated carbon treatment. Activated carbon which followed ozonation performed an effective role in finishing deodorization, and can be expected its long life effectiveness for the removal of the musty odor substances.

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