Sulphate reducing bacteria for the treatment of heavy metals contaminated waters in permeable reactive barriers

The aim of the work was the comparison between a selected reactive mixture containing organic matter for SRB and other electron donors, such as ethanol and polysaccharides. The comparison was performed in order to select the best operating conditions in terms of organic sources for SRB. A continuously operating fixed-bed column was filled with a batch-optimised solid reactive mixture (6% leaves, 9% compost, 3% zero valent iron, 30% silica sand, 30% perlite, 22% limestone) and inoculated by SRB. At steady state 50±10% sulphate abatement was reached and metals were totally removed. Batch tests with ethanol showed the ability of SRB to grow on this substrate efficiently. Experimentation using ethanol was performed using two different column reactors filled with perlite, one inoculated by SRB and the other used as blank. Sulphate abatements of the inoculated column were 70±10% against 10±5% of the blank column. Preliminary batch tests with polysaccharides showed the ability of bacteria to grow on these substrates. © (2009) Trans Tech Publications.