A pilot scale UV photooxidation system which involves a complete mixing flow type UV reactor connected in series with a multiple stage type UV reactor and a gas absorption tower filled with crashed marble has been fabricated to investigate a treatment for the trichloroethylene (TCE) gas extracted from contaminated soil. The photooxidation reaction rate in the complete mixing flow type reactor was increased with increasing the photo intensity in the reactor and was correlated with the laboratory scale experimental result. At the outlet of the multiple stage type reactor the TCE was decomposed less than 1 ppm, when the TCE concentrations at the inlet of the complete mixing flow type reactor were more than 100 ppm. The photooxidation products which exhibited acidity were found to be more effectively eliminated by the pilot scale absorption tower than by the laboratory scale tower.

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Effects of the hydraulic retention time (HRT) and loading rate on thermophilic methane fermentation of the organic fraction of municipal solid waste (OFMSW) were investigated by using a semi-continuous flow completely-mixed reactor. The experiment was conducted at a temperature of 55 °C and a constant influent TS level of 10% by changing the HRT from 5 days to 30days. The results indicate that the HRT of thermophilic digester could be shortened to 5 days without significant decrease in both the organic matter degradation and methane production, and that the digester was successfully operated at the high loading rate up to 31 kg-COD_Cr·m^-3·d^-1. The removal efficiencies of TS, VS and total COD_Cr were, respectively, in the ranges of 73-78%, 76-78%, and 72-75%, and 1 kg of influent TS produced about 0.75 m³ of digestion gas with the methane content of 57-59%. The Stoichiometric formula of the methane fermentation of OFMSW was identified as: C₁₇H₂₉O₁₀N + 6.5H₂O → 9.25CH₄ + 6.75CO₂ + NH₄⁺ + HCO₃^-, which is in accordance with the experimental results of this study. The first-order reaction was found suitable for describing the degradation of the OFMSW, and kinetic constants for TS, VS and total COD_Cr were summarized in a table. It is suggested that the applicable HRT for the high-solids digestion of OFMSW could be shortened to at least of 7.5 days, corresponding to the COD_Cr loading rate of 20 kg-COD_Cr·m^-3·d^-1, by adding mineral nutrient to the feed. In addition, the relationships between HRT and various operation parameters were determined quantitatively based on the experimental results.

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A pilot scale experiment of intermittently aerated sequencing batch reactor process (SBR) was carried out during 5 months to investigate the removal characteristics of BOD and nitrogen from a piggery wastewater. The pilot plant was set to operate in automatic control. The SBR pilot plant was operated on a 24h cycle, as mix of 5h, aeration of 15h, sedimentation of 3.5h and withdraw of 0.5h. The concentration of MLSS was highly controlled as 6,000-7,000mg·l^-1. The operation of the SBR pilot plant was conducted with low BOD volumetric loading (mean value is 0.26 BODkg·m^-3·d^-1), and very long sludge age (57d).
The percentage removals of BOD and COD_Mn during the experimental period were 99.5% (< 37mg·l^-1) and 89.9% (< 170mg·l^-1), respectively. The mean NH₄-N concentration of effluent was 10mg·l^-1 and any ammonia accumulation was not observed during the operational period except for the conditions that pH value of treated water was less than 5.5. This nitrate accumulation was because the carbon sources for denitrification was deficient. The maximal NO₃-N concentration of effluent increased up to 250mg·l^-1 at BOD/T-N 1.0. The percentage removal of T-N decreased remarkably when BOD/T-N ratio was less than 3.0. This result indicates that to maintain BOD/T-N ratio of piggery wastewater suitably is important for the treatment performance of nitrogen. Filamentous microorganisms were always observed in activated sludge, however settling control problems by filaments were not seen during the experimental period. The influence of BOD-MLSS loading on the settling process was more significant rather than the occurrence of filamentous microorganisms in activated sludge.

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Acidification of forest soils by acid rain is one of the most crucial topics today. On the other hand, the disposal method of waste oyster shell as industrial waste have not been detected. Here, we tried to reuse the oyster shell as neutralizer for acid rain. Dominant component of oyster shell is calcite (CaCO₃, wt%>98) which is able to be dissolved easily in neutral or weak acidic aqueous solutions. Acid rain was collected and analyzed the components in order to investigate the neutralization effects by waste oyster shell.

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Tropical river waters in South East Asia have been seriously polluted by recent urbanization and industrialization, and microbial ecology of bacteria in tropical rivers must be investigated. In this study, bacterial community structure and their physiological activity in tropical rivers (Kelang River basin, Malaysia) were investigated at a single cell level. Estimates of culturable bacteria on R2A medium accounted for 10 to 30% of DAPI (4',6-diamidino-2-phenylindole)-stained bacteria. The number of bacteria with enzymatic activity, as determined by 6CFDA (6-carboxyfluorescein diacetate), was 10 to 30% of the total bacteria. Bacterial community structures in tropical water samples were analyzed by rRNA-targeted in situ hybridization with HNPP (2-hydroxy-3-naphthoic acid-2'-phenylanilide phosphate) and the direct viable count approach. Forty to 55% of total cells could be detected with EUB338 probe. The bacterial community structure was dominated by the Acinetobacter group in any sample, accounting for 20 to 35% of total cells. Baterial activity and dominant genera were different from those in temperate river samples.

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In order to make clear the transformation mechanism of chemical species in pore water under reducing condition, a column experiment which reproduced redox condition, was carried out. The upper part of the column was filled with the soil taken from the paddy field and the lower of the column was filled in the quartz sand and glass beads. The major findings of experimental results are as follows:
ORP(Oxidation Reduction Potential) decreased for first ten days after the beginning of this experiment, thereafter, showed a constant value. Mn²⁺ and Fe²⁺ which were dissolved under reducing condition caused the cation exchange reaction to the other cations. When Mn²⁺ and Fe²⁺ reached an oxidized layer(quartz sand and glass beads layer), they were reprecipitated as Mn-, Fe-hydrous oxides. It was assumed that high concentrations of Mn²⁺, Fe²⁺ in pore water at depth of 35, 45cm were appeared due to the movement of soil particle and anaerobic bacteria from plow layer to quartz sand layer and the absence of exchangeable sites.

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The umbrella plant (Cyperus alternifolius L.) was planted in an eutrophic pond for water purification and restoration of ecosystem. The effluent pH value was reduced to about 7 from 9 by efficiency of shading the light. The plant removed 6% for T-N and 15% for T-P of influent nutrient. Since the number of aquatic insects increased two times in one year, aquatic insects in the pond gradually colonized by planting. The 4.3% growth rate for summer was a second value as compared with that of water hyacinth. The annual mean growth rate of the plant was 1.6%. Nevertheless, the plant is suitable for water purification because it doesn't die in winter and could be used in all seasons. The plant was planted in the developed pot with emerging and floating culture system and harvested at 60cm high from the surface of the pond water. We found this was the most efficient method of nutrient removal. The nutrient removal rates were 0.363g·m^-2·d^-1 for T-N and 0.089g·m^-2·d^-1 for T-P.

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