Interaction between iron reducing bacteria and nano-scale zero valent iron

Abstract

Zero valent iron (ZVI) is known as effective and safe material to remove chlorinated hydrocarbons as utilized in permeable reactive barriers. Iron reducing bacteria (IRB) survive through the anaerobic metabolism reducing ferric iron, as electron acceptor, to ferrous iron. It helps ZVI remediation treatment to regenerate the reactivity of iron. Nano-scale ZVI (NZVI) has been researched to improve the reactivity and the mass transfer while it has been reported that nano-scale particles have toxic or inhibitory effect on human or nature. To incorporate these two types of advanced technology for ZVI, the effect of NZVI particles on IRB metabolism was researched with high performance liquid chromatography (HPLC), ferrozine test, and colony forming unit test. It was found that the IRB in NZVI system were not harmed. In HPLC test, citrate and lactate that is an electron donor for IRB, were consumed without any inhibition effect. Additionally, in ferrozine test, ferrous iron, which was reduced from ferric iron as electron acceptor for IRB, was increased in the micro-scale ZVI (MZBI) system. Since NZVI has high specific surface area, both HPLC and ferrozine tests show NZVI system has higher IRB metabolism rate than MZVI system and no iron system.