Bertolino Sueli M, Melgaço Lucas A, Sá Renata G, Leão Versiane A
Bio & Hydrometallurgy Laboratories, Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, s.n., Bauxita, Ouro Preto, MG, 35400-000, Brazil.
Biodegradation. 2014 Sep;25(5):719-33. doi: 10.1007/s10532-014-9694-1. Epub 2014 Jun 15.
Among the greatest challenges to the full implementation of biological sulfate reduction are the cost and availability of the electron source. With the development of the biofuel industry, new organic substrates have become available. Therefore, this work sought to compare the performance of a sulfidogenic process utilizing either lactate or glycerol as the substrate for sulfate-reducing bacteria (SRB) growth. Although sulfate reduction is energetically more favorable with lactate, glycerol is a less expensive alternative because excess production is forecasted with the worldwide development of the biodiesel industry. Continuous experiments were performed in a fluidized bed (FB) reactor containing activated carbon as a carrier for a mixed bacterial population composed of sulfate-reducing and fermentative bacteria. During the lactate-fed phases, incomplete oxidation of lactate to acetate by SRB was the dominant metabolic pathway resulting in as much as 90 % sulfate reduction and high acetate concentrations (2.7 g L(-1)). Conversely, in the glycerol-fed phases, glycerol degradation resulted from syntrophic cooperation between sulfate-reducing and fermentative bacteria that produce butyrate along with acetate (1.0 g L(-1)) as oxidation products. To our knowledge, this is the first report of butyrate formation during sulfate reduction in a glycerol-fed continuous-flow reactor. Sulfate concentrations were reduced by about 90 % (from 2,000 to 100-300 mg L(-1)) when glycerol was being fed to the reactor. Since the FB reactor was able to stand a change from lactate to glycerol, this reactor is recommended as the preferred option should glycerol be selected as a cost-effective alternative to lactate for continuous sulfate reduction.
全面实施生物硫酸盐还原面临的最大挑战之一是电子源的成本和可用性。随着生物燃料行业的发展，新的有机底物已经出现。因此，本研究旨在比较以乳酸或甘油为底物培养硫酸盐还原菌（SRB）的产硫化过程的性能。尽管以乳酸进行硫酸盐还原在能量上更有利，但甘油是一种成本较低的替代品，因为随着全球生物柴油行业的发展，预计会有过量的甘油产生。在一个流化床（FB）反应器中进行了连续实验，该反应器以活性炭为载体，用于培养由硫酸盐还原菌和发酵菌组成的混合菌群。在以乳酸为进料的阶段，SRB将乳酸不完全氧化为乙酸是主要的代谢途径，导致高达90%的硫酸盐还原和高浓度的乙酸（2.7 g L(-1)）。相反，在以甘油为进料的阶段，甘油的降解是由硫酸盐还原菌和发酵菌之间的互营合作导致的，它们产生丁酸以及乙酸（1.0 g L(-1)）作为氧化产物。据我们所知，这是关于在以甘油为进料的连续流反应器中进行硫酸盐还原过程中形成丁酸的首次报道。当向反应器中进料甘油时，硫酸盐浓度降低了约90%（从2000降至100 - 300 mg L(-1)）。由于FB反应器能够承受从乳酸到甘油的转变，因此如果选择甘油作为比乳酸更具成本效益的连续硫酸盐还原替代物，推荐该反应器作为首选选项。
