Cost, energy and GHG emission assessment for microbial biodiesel production through valorization of municipal sludge and crude glycerol

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

“…Several processes have been reported for biodiesel production from microbial lipid. The process employing commercial substrates (glucose, peptone and yeast extract) for fermentation and energy intensive solvents (chloroform and methanol) during lipid extraction was energetically unfavorable [27]. Lipid extraction step contributed 70.5% of total process energy input due to the high volume and energy content of chloroform and methanol [27].…”

“…The reported downstream process has economic and environmental advantages over traditional broth harvesting, which employs continuous centrifuge followed by biomass drying. The lipid from dry biomass is extracted using toxic solvents [27]. The biomass settling was performed using 52 mM calcium chloride and 39.9 mg EPS/g biomass of bio-flocculant (EPS-extra-cellular polymeric substances) [26].…”

“…After lipid extraction, the left waste is cell debris containing structural components of cell mass, including carbohydrates, humic substances, and proteins, which are released during the breakdown of cell wall. The cell debris can be used as fertilizer [29] or as animal feed supplement [27].…”

“…The energy input due to chemical addition was taken from literature [18,30,31]. The energy consumed during the agitation, centrifugation and mixing were taken from the literature [22,27,32]. The mass of chemicals required for the biodiesel production is in the column 'amount supplied'.…”

Comparative Technoeconomic Analysis of Using Waste and Virgin Cooking Oils for Biodiesel Production

“…Enzyme catalysts lead to higher reaction rates than acid catalysts; however, they are unpractical to use in industrial scale due to their high price (Tabatabaei et al, 2019;Urbain et al, 2019). Transesterification reaction can be performed without a catalyst in supercritical conditions however, it is not economically feasible since these conditions require high utility costs (Kumar et al, 2020).…”