Effect of Varying Zinc Concentrations on the Biomethane Potential of Sewage Sludge

The anaerobic digestion of sewage sludge is highly sensitive to high zinc concentrations. Although sulfate-reducing bacteria (SRB) activity can negatively affect methanogenesis, SRB-mediated metal sulfide precipitation alleviate toxicity. A series mesophilic batch experiments was performed for the biomethane potential three different samples 74 days using background content, alone or in combination with external addition 200, 300 and 400 mg Zn/L. highest production 165 ± 1 mL CH4/g VS activated (AS) a concentration 93 slight decrease yield (i.e., 157 1, 158 159 VS) obtained presence 293, 393 493 Zn/L, respectively. reason methanogenic at inlet Zn concentrations could be that AS used this study already acclimated those conditions. Zinc likely removed from system by precipitation, removal efficiency above 99% achieved under all sulfate reduction also obtained. Overall, details utilization biogenic as detoxifying agent without detrimental effects on methane sludge.