報告書番号

U96007

タイトル（和文）

微生物による石炭灰および放射性廃棄物からの重金属類の回収・除去技術に関する文献調査微生物による石炭灰および放射性廃棄物からの重金属類の回収・除去技術に関する文献調査

タイトル（英文）

REVIEW OF MICROBIAL RECOVERY AND REMOVAL OF HEAVY METALS FROM COAL ASH AND NUCLEAR WASTE.

概要 （図表や脚注は「報告書全文」に掲載しております）

内外約１５０報の文献について調査し，微生物を用いた廃水からの重金属除去法を４つに分類した。（１）細胞表面に吸着させ，沈澱させる方法，（２）細胞内に取り込み蓄積する方法，（３）代謝を利用して可溶性の重金属を還元あるいは酸化して不溶化させる方法，（４）細胞由来の生体高分子（細胞壁構成成分，金属捕捉タンパク質，色素等）を直接用いて重金属を捕捉する方法である。本法の廃水処理への応用として，吸着法あるいは生体高分子法を用いた放射性廃棄物からの重金属の除去や吸着法あるいは酸化・還元法を用いた石炭灰からの重金属の除去等が考えられた。

概要 （英文）

RECOVERY OF HEAVY METALS FROM WASTE WATER ISIMPORTANT FOR ENVIRONMENTAL PROTECTION AND IS ALSO ESSENTIAL FOR METALRECYCLING APPLICATION OF BIOTECHNOLOGY TO RECOVERY AND REMOVAL OF HEAVY METALS HAS BECOME OF INTEREST IN RECENT YEARS.IT HAS BEEN REPORTED THAT MANY MICROORGANISMS CAN ACCUMULATE HEAVY METALS.MICROBIAL METHODS MIGHT BE APLIED TO TREATMENT OF HEAVY METALS. METAL REMOVAL BY MICROORGANISMS IS CLASSIFIED INTO FOUR METHODS:(1)ADSORPTION; THIS METHOD REMOVE HEAVY METALS FROM WASTE WATER BY ADSORPTION THE SURFACE OF BACTERIAL CELLS. (2)INTRACELLULAR ACCUMULATION; HEAVY METALS ARE REMOVED FROM WASTEWATER BY TRANSPORTATION INTO THE BACTERIAL CELLS. (3)OXIDATION-REDUCTION;METALIONS IN THE WASTE WATER ARE PRECIPITATED BY BACTERIAL OXIDATIONOR REDUCTION. (4)MACROMOLECULE BINDING;THE METAL IONS BIND TO MACROMOLECULES DERIVED FROM MICROORGANISMS.THE CHITIN AND CHITOSAN IN CELL WALLS,METAL-BINDING PROTEINS,SHIDEROPHORES AND BIOPIGMENTS ARE USED AS METAL BINDERS. WE INVESTIGATED MICROBIAL REMOVAL OF HEAVY METALS FROM NUCLEAR WASTE AND COAL ASH.(1)NUCLEAR WASTE:REMOVAL OF HEAVY METALS BY MICROBIAL METHODS HAS BEEN REPORTED FOR SC,RA,CS,SR,TC,PU,NP AND U.FROM THE VIEW POINTS OF ACCUMULATION CAPACITY AND REMOVAL RATIO PER DRY WEIGHT OF ADSORBENT,THE ADSORPTION AND MACROMOLECULE BINDING METHODS WOULD BE SUITABLE.FOR EXAMPLE,THE METAL ADSORPTION CAPACITIES OF MICROORGANISMS USING THE ADSORPTION METHOD ARE 2 TO 7 TIMES LARGER THAN THAT OF ION-EXCHANGE RESIN OR ACTIVATED CARBON.(2)COAL ASH:THE REMOVAL OF HEAVY METALSBY MICROBIAL METHODS HAS BEEN REPORTED FOR CD,CR AND PB.THE ADSORPTIONAND OXIDATION-REDUCTION METHODS ARE BEST BECAUSE THESE METHODS HAVE LARGE TREATMENT CAPACITIES. ADSORPTION AND OXIDATION-REDUCTION ARE ALREADY USED IN WASTEWATER TREATMENT AT MINERAL MINES.MICROBIAL METHODS HAVE FUTURE POTENTIAL FOR REMOVING METALS FROM WASTE WATER IN ELECTRIC UTILITES

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