Biodegradation of Reactive Black 5 and bioregeneration in upflow fixed bed bioreactors packed with different adsorbents

BACKGROUND: Unutilized dyes present a significant environmental problem. Recently, biological activated carbon has been used extensively for the removal of gas and wastewater pollutants but its use in dye removal is still limited. The system provides simultaneous adsorption of pollutants and biodegradation/biotransformation of pollutants in a single reactor, and showed high efficiency and a long working life. RESULTS: The adsorption of Reactive Black 5 by three selected adsorbents, F400, bone char and bamboo activated carbon, was studied. The relationships between adsorption, desorption, bioregeneration and the effect of nutrient on dye adsorption was assessed. The potential value of using adsorbents as a microbial support in the biodegradation of Reactive Black 5 was investigated. Biodegradation was greatly enhanced in the fixed bed bioreactors and complete decolorization was achieved in all the reactors studied with hydraulic retention time less than 15minutes. The bioregenerated adsorption capacity of bamboo activated carbon in the bioreactor was found to be the highest. CONCLUSION: Decolorization of Reactive Black 5 was significantly enhanced in the bioreactors. Results showed that the immobilized bacteria can increase the desorbability of the adsorbed dye, which is important for practical operation, and that bamboo activated carbon demonstrated potential as a packing material in fixed bed bioreactors.