Enhancement of anaerobic digestion of microcrystalline cellulose (MCC) using natural micronutrient sources

Abstract

The effect of adding four minerals as micronutrient sources to stimulate the anaerobic process of microcrystalline cellulose (MCC) was investigated. Three mineral doses (5, 10 and 15 mg/L) were evaluated and the response to trace metal addition was monitored by the methane yield (Y CH4) and specific methanogenic activity (SMA). A clear stimulation of the Y CH4 and SMA on MCC due to the presence of minerals with a high content of trace elements was observed, respectively: the Y CH4 and SMA of the sludge with 5 mg/L of high-Fe-Mg mineral increased to 397 NmLCH4/gVSsubstrate and 0.267 gCOD NmLCH4/gVSinoculum/d compared to 303 NmLCH4/gVSsubstrate and 0.205 gCOD NmLCH4/gVSinoculum/d in a medium without adding mineral. An increase in the doses of high-Ca mineral highly decreased methane production and process stability, due to a possible inhibition of the anaerobic digestion by calcium ions.