Influence of mixing on anaerobic digestion efficiency in stirred tank digesters: A review

A comprehensive review was carried out on the influence of mixing on anaerobic digestion (AD) efficiency in stirred tank anaerobic digesters. Though traditionally, stirred tank digesters operated as continuous stirred tank reactors (CSTRs), this review revealed that there is no motivation to continue to operate stirred tank anaerobic digesters as CSTRs if AD energy efficiency is to be improved. AD energy production efficiency can be achieved with optimized intermittent mixing. AD efficiency should include an assessment of the net energy production efficiency and should be the criteria in determining the mixing mode, mixing intensity, mixing time and mixing interval for every anaerobic digestion operating plan.