RESUMO
A biological methanation system based on nutrient recycling via mixed culture microbial catabolism was investigated at mesophilic (37⯰C) and thermophilic (55⯰C) temperatures. At mesophilic temperatures, the formation of biofilms on two different types of material was assessed. Results showed that with intense mixing the biofilm reactors presented methanogenic capacities (per working volume) 50% higher than the ones operated with suspended cultures. Gas feeding rates of 200â¯L/L/d were achieved at a H2/CO2 to CH4 conversion efficiency of above 90% by linking two reactors in series. Furthermore the robustness of the cultures was assessed under a series of inhibitory conditions that simulated possible process interferences at full scale operation. Full recovery after separate intense oxygenation and long starvation periods was observed within 2-5â¯days.