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Hexavalent chromium removal by viable, granular anaerobic biomass

Massara, Hafez, Mulligan, Catherine N., Hadjinicolaou, John
Bioresource technology 2008 v.99 no.18 pp. 8637-8642
industrial effluents, wastewater, chromium, toxicity, anaerobes, sorption, bioremediation, biogas, chemical oxygen demand, methanogens, bacteria, inhibitory concentration 50, viability, simulation models, uptake mechanisms, waste treatment
Hexavalent chromium in industrial wastewater is a major concern due to its extreme toxicity. This study investigates the removal of Cr(VI) using viable anaerobic granular biomass as a biosorbent. The effect of Cr(VI) concentration on biogas content and COD removal using batch studies indicated that the phase II (methanogenic-rich) culture was more sensitive than the phase I (acidogenic-rich) culture. Toxicity indices for both cultures using COD removal were developed based on linear-log interpolation. The median inhibition Cr(VI) concentration (IC₅₀), for phase II cultures was found to be 263mg/L, while that for phase I cultures was 309mg/L. A sorption study was conducted on viable and non-viable (dried) phase I-rich biomass: both followed the Langmuir model. In addition, the biosorption capacity for metabolically inhibited biomass was 25% less indicating some level of cellular uptake associated with Cr(VI) removal. This study demonstrated the potential for a two-phase anaerobic treatment system for a Cr(VI)-contaminated effluent.