Precipitation of Zn(II), Cu(II) and Pb(II) at bench-scale using biogenic hydrogen sulfide from the utilization of volatile fatty acids

Biological production of hydrogen sulfide (H2S) using sulfate-reducing bacteria (SRB) has important potential within environmental biotechnology. The aim of this work was to study the possibility of using SRB for the treatment of an acid mine drainage (AMD) at bench-scale. This process involved three stages: the optimization of H2S production through the utilization of total volatile fatty acids (TVFAs) by SRB, the establishment of a biofilm reactor for sulfide production, and the precipitation of metals by using the biologically produced H2S. The substrates used for TVFAs production consisted of papaya, apple and banana. The H2S produced from the degradation of TVFAs was utilized for the precipitation of a metal-contaminated effluent collected from Bolivar mine (Oruro, Bolivia). The maximum concentration of H2S obtained was approximately 16 mM. Removal efficiencies of ca. 100% for copper, above 94% for zinc, and above 92% for lead were achieved.