Pilot-scale tests were carried out for nitrogen removal from ammonium plant effluent using gel carriers on which anaerobic ammonium oxidation (anammox) sludge was immobilized. The nitrogen removal system was equipped with an anammox vessel of 5 m³ volume and the pretreatment processes were carried out for continuous feeding tests. The nitrogen removal in the anammox vessel could be started up within approximately 2 months of acclimation using ammonia synthetic plant effluent (ammonia wastewater) at 30°C. After that, stable nitrogen removal in the anammox vessel was confirmed at 16.1°C even though the influent was changed to another kind of wastewater based on urea. Moreover, nitrogen removal in the anammox vessel reached the designated denitrification rate within 3 days at 30°C after influent wastewater was returned to the original ammonia wastewater. Finally, the anammox vessel was operated using the ammonia wastewater at a low water temperature. The nitrogen conversion rate was stably observed 1.9 kg-N•m³•d^-1 at 17.1°C. These results strongly suggest that this nitrogen removal system using anammox gel carrier can be applied to nitrogen removal from industrial effluent under low water temperature.

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The purpose of this study is to evaluate the relationship between the improvement of soil permeability upon mixing with gravel-size materials and the water purification performance of a multi-soil-layering system. Focusing on the practical use of regional resources, zeolite, Sekisyu roofing tiles, Kimachi stone, Corbicula shell and bamboo charcoal, which are regional resources in Shimane prefecture, were used as gravel-size materials. Mixing these materials, especially Corbicula shell but not zeolite, with soil improved the permeability of the soil mixture layer. The calcium from the shell probably stabilized the soil structure, resulting in the high permeability. On the other hand, the high content of exchangeable sodium in zeolite probably dispersed the soil particles and decreased the permeability. Sekisyu roofing tiles had low chemical properties for water purification. The effect of Kimachi stone on improving the permeability was poor owing to the high exchangeable sodium content and its fragility. Bamboo charcoal had a high removal capacity of organic matter. The increase in the amount of outflow through the soil mixture layer enhanced the water purification capacity, especially for phosphorus. The use of regional resources enabled the improvement of the water purification capacity and is probably applicable in a multi-soil-layering system.

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Sphingobium fuliginis OMI, a 4-t-butylphenol utilizing bacterium, can degrade bisphenol S (BPS), which is known to be a persistent substance. In the present study, we estimated the BPS degradation pathway by the strain OMI. Additionally, the possibility of the removal of the BPS metabolites by using activated sludge was evaluated. One or two of the phenolic rings of BPS was initially hydroxylated and then, the aromatic ring was cleaved via a meta-cleavage pathway by the strain OMI. Since several metabolites remained as dead-end products, a negligible amount of DOC was removed during BPS degradation by the strain OMI. Also, activated sludge removed neither BPS nor DOC. On the other hand, the BPS metabolites, which are produced from the BPS degradation by the strain OMI, were removed by using activated sludge, through biodegradation, adsorption and/or chemical decomposition, resulting in a 39% decrease in DOC. The present study demonstrated that the initial degradation of BPS by the strain OMI could be useful for the removal of BPS by the activated sludge process.

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We evaluated the processing capacity of a water purification system for low-organic-content wastewater from a poultry grading and packing facility. The system comprised vertical-flow intermittent feeding constructed wetlands connected in series. The BOD (Biochemical Oxygen Demand) of the water treated in the first stage was 6.8 mg•L^-1. After stabilization at the facility, it was about 2-3 mg•L^-1, for a decrease in BOD of 90% or more. SS (Suspended Solid) and BOD were removed in Wetland 1, where coarse particles were used as filter material, but D-BOD (Dissolved BOD) removal tended to occur in Wetland 2, where fine particles were used. The NH₄-N concentration at each survey point was low, but the NO₃-N concentration tended to increase with downstream flow. NH₄-N generated by mineralization was rapidly nitrified. The average OTR (Oxygen Transfer Rate) value was 6.5 g•m^-2•day^-1, which is much less than 28 g•m^-2•day^-1, the standard in the United States and Europe, but the upper load limit was not confirmed. Filling the wetlands with water took longer in winter than in summer. The decomposition of solid organic materials is delayed by clogging in winter, but the water temperature rises in summer, suggesting an improved discharge capacity owing to organic matter decomposition.

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In the palm oil mill effluent (POME) discharged during the production process of palm oil, oil is contained in the emulsion state. Currently, the open ponding system (facultative/anaerobic lagoons) is being applied as the main treatment method for POME owing to low operating costs. However, the main disadvantages of this system are the requirement of large land area, long retention time, and low treated-water quality. In this study, we developed a novel oil-water separation technique involving the use of a combination of micro- and normal bubbles for POME in order to reduce the environmental load as well as recover/reuse the separated oil. With the combination of micro- and normal bubbles, normal bubbles can accelerate the up-flow rate of microbubbles, improving the oil-water separation efficiency. As a result, it was confirmed that the combination of micro- and normal bubbles could improve the efficiency of oil-water separation. It was also confirmed that the effectiveness of this combination for actual treatment of POME was demonstrated in Thailand. The efficiency of oil-water separation of actual POME treated by the combination of micro- and normal bubbles was increased about 40% compared with that when only microbubbles were applied.

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