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This study was conducted to evaluate (i) the characteristics of ammonia gas emissions from soybean cultivation soils amended with varying levels of urea and soil water, and (ii) the rate of reduction in ammonia emissions that could be obtained by applying mixed microorganisms (MM) to the urea-treated soils. The ammonia gas emissions from all treatments except the control were highest on day 2 of a laboratory-scale experiment and decreased gradually thereafter. The ammonia gas emissions from the soils increased with increasing urea and soil water contents. However, there were less emissions from soils treated with MM than those from the urea only treatment, and emissions also decreased significantly as the concentration of MM increased. In a field-scale experiment, the total cumulative emissions of ammonia from soil treated with a combination of chemical fertilizers and MM was reduced to 85.8% of that from the soil treated with chemical fertilizers only. Although we infer that MM can be used as an agent to reduce ammonia gas emissions from actual soils used for soybean cultivation, our knowledge of the processes involved in reducing ammonia emissions using microbial treatment is still limited. Consequently, further studies are required to investigate the efficient control of ammonia gas emissions from agricultural soils through the application of microorganisms.

This study evaluated the characteristics and mechanism of phosphate adsorption by fly ash discharged from a biomass thermal power plant (BTP-FA) under various environmental conditions in order to increase the recyclability of BTP-FA. The phosphate adsorption properties of BTP-FA and fly ash derived from coal thermal power plant (CTP-FA) were better matched by those predicted by the Langmuir isothermal model and the pseudo-second-order model, and their maximum adsorption capacities were 62.1 and 4.1 mg/g, respectively. It was found that the adsorption of phosphate by BTP-FA was predominantly influenced by the outer boundary layer rather than the inner diffusion in the pores. The phosphate adsorption process by BTP-FA was greatly influenced by the initial pH and the BTP-FA dose. Therefore, to effectively treat phosphate using BTP-FA, the concentration and flow rate of phosphate in the incoming wastewater must be considered. The concentration of dissolved calcium from BTP-FA decreased sharply during the phosphate adsorption process compared to that in the phosphate-free solution. This was thought to be due to surface adsorption/reaction between calcium and phosphate. The SEM–EDS and FTIR results also supported the surface adsorption/precipitation reaction of Ca-P. Recycling fly ash discharged from biomass power plants as phosphate adsorbents is expected to contribute not only to waste reduction, but also to wastewater purification.

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BACKGROUND: Most of the researches on the dye removal using ozonation have been focused on the removal efficiency. However, the research on their removal characteristics and mechanism according to the reaction time has been still insufficient. METHODS AND RESULTS: In this study, the effects of initial pH and dye concentration with reaction time on the degradation characteristics of methyl orange (MO) and methylene blue (MB) by ozonation were evaluated. The degradation efficiency of MB by ozonation increased with increasing pH. On the other hand, the degradation efficiency of MO by ozonation did not show a significant difference with varing pH. The both MO and MB by ozonation were decomposed within 30 min irrespective of the dye concentration, but the decomposition rates of dyes were faster at lower initial dye concentration. The decomposition