Biodiesel production from microbial lipid obtained by intermittent feeding of municipal sludge and treated crude glycerol

Abstract

In the present study, municipal secondary sludge and purified glycerol (obtained after acid treatment of crude glycerol) were used together for lipid production using intermittent feeding strategy. Intermittent sludge feeding strategy (sludge SS 30 g/L) resulted in a higher biomass (54.99 g/L) and lipid concentration (25.35 g/L) at 96 h when compared to 35 g/L SS single sludge feeding or control strategy (45.67 g/L biomass & 19.16 g/L lipid). Moreover, the intermittent sludge feeding strategy significantly reduced foaming and requirement of anti-foam during fermentation when compared to control strategy. The energy balance of biodiesel production from lipid obtained by intermittent sludge feeding strategy (30 g/L SS) was energetically favorable. It was also revealed from yield coefficients and energy balance that sludge had an important contribution in microbial lipid and biodiesel production.