Although nitrate (NO₃^-) contamination of groundwater has been broadly detected, determinig NO₃^- pathways to the groundwater still remains a challenge. In unsaturated soil, where NO₃^- moves through, sitting over the groundwater table, soil water content always changes due to rainfall and evapotranspiration. Thus, it is speculated that behaviors of NO₃^- dissolved in soil water might be complex in unsaturated soil. Using time domain reflectometry (TDR) we in situ measured temporal changes in water and NO₃^- contents in Andisol applied with animal manure. On a rainfall event, water infiltrated into greater than 40 cm deep whereas NO₃^- just reached as deep as 10 cm from the soil surface.

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Arsenic contamination of groundwater is found to be one of the most serious problems Bangladesh and surrounding region. This research report aim to investigate the removal mechanism of arsenic in oxidation-sand filtration process installed in a small community in Bangladesh. In order to remove arsenic at satisfactory level, the existence of iron with arsenic is found to be very important. Low concentration of iron may results unsatisfactory arsenic removal efficiency. Laboratory experiment exhibited that arsenic associated with small particles of iron hydroxide was the major species of arsenic released from the filter. This phenomenon is the major mechanism of leakage of arsenic from sand filters. In the sand filtration system, up-flow filtration was more effective than down-flow filter.

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Contamination of soil and groundwater by organic contaminants usually appears when the contaminants have reached the groundwater table long time after they first started leaking from underground storage facilities. Since remediation of soil and groundwater takes much time and efforts, a sensor that can detect contaminants in soil in the early leaking stage has been desired. Currently-available sensors only detect contaminants under steady soil water content conditions. Using a thermo-time domain reflectometry (TDR) probe, a new technique was introduced to measure contaminants' concentration. The thermo-TDR probe detected ethanol concentration up to 50% (v/v) in a sandy soil variably saturated with water-ehtanol mixtures.

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For taking measures to reduce greenhouse gas emission in small-to-medium-sized enterprises, it is discussed about how to evaluate their performance in management of the enterprises in this paper. In addition to a new assessment with a “spiral checking and feedback system”, a new management based on this assessment is proposed for reasonable evaluation of the taking measures and the CO₂ reduction. A quantitative case study is conducted according to procedure and estimation of the above method for a company manufacturing construction materials. This study reveals that the saving of energy cost, which is attained by the suitable taking measures, brings about a effective profit to the manufacturer.

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To improve treatment efficiency of thermophilic oxic process (TOP) treating swine waste, the effect of shortening the waste-input cycle was examined. By shortening the waste-input cycle from 24 h to 8 h, the maximum loading rate of swine waste per day could be improved 2.3 times and necessary amount of auxiliary heat source was reduced. A high temperature in the reactor maintained by shortening the waste-input cycle was found to contribute to stimulate the activity of thermophilic bacteria, resulting in improvement of treatment efficiency and reduction of necessary auxiliary heat source. A long term TOP operated by 8 h cycle for waste-input with an optimal auxiliary heat source addition confirmed the treatment feasibility of TOP during 120 cycle (for 40 days) concerning treatment efficiency and maintenance of moisture content in the reactor. This study demonstrated several merits of shortening the waste-input cycle of TOP.

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A UCT-type pilot plant was operated for two and a half year. The phosphate removal activity tended to be unstable in low temperature terms although the nitrogen removal activity was stable through the operation period. As it was considered that the point at issue is low MLSS concentration in the anaerobic tank, high circulation ratio of denitrified mixed liquor from the anoxic to anaerobic tank was adopted. MLSS concentration in the anaerobic tank became higher a little, but phosphate removal was still unstable. In order to hold the MLSS concentration in the anaerobic tank much higher, the return sludge sent back to not only the anoxic tank but also the anaerobic tank. Since high MLSS concentration made high amount of organic matter consumption in the anaerobic tank, carry-overs of the organic matter to the anoxic tank decreased. Consequently, a population ratio of the PAOs rose, and the higher phosphate removal activity was achieved even if in low-temperature terms.

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