Effects of Cobalt, Nickel, and Selenium/Tungsten deficiencies on changes in anaerobic microbial community structure and function

Availability of trace elements (TE) is vital for growth and activity of anaerobic microbial communities due to their role as coenzymes in many key metabolic pathways. This is relevant for systems such as anaerobic digestion in continuous stirred-tank biogas reactors (CSTBR), where optimal microbial activities are vital for achieving economic feasibility of the processes. The aim of this study was to determine specific effects of TE deficiency on microbial activity and process performance of CSTBR processes. Three CSTBR (R2 – R4) were depleted of Ni, Co, and a combination of Se and W, respectively, while one additional reactor (R1) served as a control. Ni and Se/W depletion led to a progressive VFA accumulation and eventually system failure due to over-acidification. No significant changes were observed in the Co-depleted reactor even after 6 HRT, indicating a possible contamination with Co.