“…This is a by-product of biodiesel production that contains approximately 50-60% glycerol, 12-16% alkali soaps and hydroxides, 15-18% methyl-ethers, 8-12% methanol and 2-3% water. With the development of the biodiesel industry, a surplus of crude glycerol is foreseen, but it has been tested mostly as a substrate for methane production (Álvarez et al, 2010;Fountoulakis and Manios, 2009;Lopez et al, 2009;Yang et al, 2008), and only a few studies have addressed glycerol application as a potentially inexpensive carbon and electron source for SRB growth (Dinkel et al, 2010;Qatibi, 1990). Therefore, this work initially sought to assess the performance of two different bioreactors treating sulfate-laden waters: (i) an UASB reactor, which has a simple and inexpensive design and does not require a supporting material for bacterial growth, and (ii) a FB reactor, in which activated carbon was utilized as support.…”