DEVELOPMENT OF INTEGRATED ENVIRONMENTAL PROTECTION TECHNOLOGY USING BIO-BRIQUETTES MANUFACTURED FROM LOW-GRADE COAL, BIOMASS WASTE, AND SLAKED LIME, AND ITS COMBUSTION ASH FOR DEVELOPING COUNTRIES

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Coal-biomass briquettes (BBs), which are composed of low-grade coal, biomass waste, and a sulfur fixation agent, emit less sulfur dioxide (SO_2) during combustion than low-grade coal ; thus, BBs are a good manufactured product for use as a domestic and light industrial fuel in rural areas subject to acid rain in China. The aim in this investigation is the development of the utilization technique for combustion ash of BBs (BB ash) as an amelioration agent for acidic soil because it has high alkalinity and contains a lot of nutrients.Growth experiments were conducted to estimate the effects of the addition of BB ash to acidified soil (5wt% in the acidified soil) on the growth of radish plants and on the amounts of metals in plant tissue samples by using a growth chamber. The dry weight and length of plants were increased by the addition of BB ash to the soil, suggesting that plant growth was promoted because BB ash both neutralized acidified soil and contained much calcium, a plant nutrient. In addition, the addition of the BB ash inhibited the leaching of some phytotoxic metals (aluminum and manganese) from the BB ash and acidified soil and also inhibited the adsorption of the metals by plants. The BBs made of water plant such as reed, cattail, and water hyacinth had a high breaking strength and their combustion ash could use as not only soil neutralizing agent but also soil fertilizer.These results suggest that BB ash is suitable as an amelioration agent for acidic agricultural soils. In addition, it was estimated that the adverse effect in soil environment was small because the impact of heavy metal derived combustion ash was small.