| 研究開始時の研究の概要 |
This research is aimed at the improvement of agricultural production in salinised arid land over central Asia and Middle Eastern countries. To remove salts from the soil, cultivation of halophytes that are capable in accumulation of salts in their biomass is conducted. The cultivated plant biomass is further experimentally investigated to harvest beneficial product (e.g. biogas using anaerobic biological system). As sulphate is known to be one of the salts in the salinised soil, sulphide generated from the anaerobic reaction, this toxic compound is removed with ferric materials.
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| 研究実績の概要 |
Halophytes has recently prompted researchers to consider using halophytes as a phytoremediation end-product as a source for biogas generation. Therefore, applying anaerobic digestion process is advantageous in terms of efficient land utilization, soil remediation, and biogas production. The anaerobic digestion efficiency of high saline biomass was investigated in continuous laboratory-scale anaerobic reactors at two different sludge residence times of 40 and 80 days. Under mesophilic atmosphere, two reactors were operated, one reactor used organic substrate with 30 g-Na+.L-1 originating from sodium chloride whereas the other was operated with the presence of sodium bicarbonate and sodium sulfate. The salt-tolerant microorganism was gradually developed and the salt concentrations were selected based on the elemental analyses results of 30 species of wild halophyte plants taken from the saline-affected area of the Aral Sea in Uzbekistan during the early phase of the operation. For 40 and 80 days of SRT, respectively, 65.56 percent and 60.42 percent of the feed COD were converted into methane gas by the chloride system. Only about 60% of the feed COD was converted into methane for bicarbonate, and the remaining fraction of gas was assigned to sulfide as a final product of increased sulfate reduction bacteria activity. These findings showed that the salt-tolerant microorganism could be incubated and the anaerobic digestion process could be adapted for a high-saline substrate, implying that the biodegradability of phytoremediation end-products may be used for methane production.
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