Potential of industrial by-products and wastes from the Iberian Peninsula as carbon sources for sulphate-reducing bacteria

Abstract

Industrial by-products and wastes from Portugal and Spain were tested for the first time as carbon sources/electron donors for sulphate-reducing bacteria. Cultures in mineral medium supplemented with the tested substrates were monitored, and sulphate reduction efficiency is discussed in light of substrates compositions, dosages and corresponding chemical oxygen demand/[SO42−] ratios. The results reveal the ability of those substrates to feed SRB and confirm that testing doses targeting ratios of 1.5 and values close to this was a good strategy to optimize sulphate reduction activity. As expected, this activity was faster for substrates that have in their composition simple compounds (such as low-chain alcohols and organic acids) and/or compounds that can be rapidly degraded (such as sugars), though it also occurred in a longer-term perspective with substrates composed mainly of slowly degradable compounds (such as cellulose and lignin). Thus, this work demonstrates the potential of new substrates and respective required doses to feed SRB bioreactors in long-term passive bioremediation processes or faster more active processes. That is, it opens the way for the use of such substrates in the treatment of sulphate-rich waters, as the acid mine drainage generated in some mines on the Iberian Pyrite Belt region, and it encourages further experiments to evaluate the use of SRB-based processes to treat the industrial wastewaters successfully tested in this work themselves, specially the olive mill wastewater which is still a problem for many small olive oil producers.