Hexavalent Chromium Reduction by Bacillus sp. in a Packed-Bed Bioreactor

Abstract

The potential for fixed-film biorectors to reduce Cr(VI) was demonstrated using a Cr(VI)-reducing species, Bacillus sp. A bench-scale, packed-bed bioreactor was operated to steady-state conditions under a range of influent Cr(VI) concentrations (10−200 mg/L) and hydraulic detention times (6−24 h, clean bed) with near complete removal of Cr(VI). The steady-state Cr(VI) reduction efficiency was not affected by the influent Cr(VI) concentration or hydraulic detention time. Chromium mass balance analysis revealed that nearly all the Cr(VI) fed to the bioreactor was accounted for in the effluent as Cr(VI) and Cr(III). Total cell mass in the bioreactor decreased with increasing Cr(VI) loading rate, but it stabilized after a loading limit was reached (1016 mg of Cr(VI)/L·day) when operated under 24 h hydraulic detention time. The bioreactor showed strong resilience by recovering from Cr(VI) overloading through reduction in influent Cr(VI) concentration.

Chromium (VI) reduction in activated sludge bacteria exposed to high chromium loading: Brits culture (South Africa)

“…grown under anaerobic conditions. Since then, several researchers have isolated new microorganisms that catalyse Cr(VI) reduction under varying conditions (Ackerley et al, 2004;Chirwa and Wang, 1997a;Ohtake et al, 1990;Ganguli and Tripathi, 2002;Suzuki et al, 1992;Ramírez-Ramírez et al, 2004;Shen and Wang, 1993;Baldi et al, 1990). Other researchers have also observed Cr(VI) reduction in consortium cultures isolated from the environment (Chirwa and Wang, 2000;Stasinakis et al, 2004;Dermou et al, 2005;Chen and Gu, 2005;Chang and Kim, 2007).…”

Removal of Cu and Cr from an industrial effluent using a packed-bed column with algae Gelidium-derived material

“…Similar results were obtained using the Bacillus sp. bacterium and Ecklonia brown algae (Chirma and Wang, 1997;Park et al, 2004). Fig.…”

Biological Cr(VI) Reduction: Microbial Diversity, Kinetics and Biotechnological Solutions to Pollution

“…Since then, several researchers have isolated new microorganisms that catalyse Cr(VI) reduction to Cr(V) or Cr(III) under varying conditions (Shen & Wang, 1993;Chirwa & Wang, 1997a;Ackerley et al, 2004;Zakaria et al, 2007). Other researchers have also observed Cr(VI) reduction in consortium cultures isolated from the environment (Chirwa and Wang, 2000;Chen and Gu, 2005).…”

“…In the latter process, Cr(VI) serves as a terminal electron acceptor in the membrane electron-transport respiratory pathway, a process resulting in energy conservation for growth and cell maintenance (Horitsu et al, 1987;Ishibashi et al, 1990). In the dissimilatory/respiratory process, electrons are donated from the electron donor to Cr(VI) via NADH (Chirwa & Wang, 1997a).…”