Lipid Production for Biodiesel from Sludge and Crude Glycerol

Abstract

Oleaginous yeast Trichosporon oleaginosus was studied for lipid production using municipal sludge with or without fortification of crude glycerol in a 15-L fermenter. The maximum lipid content (concentration) was 32.0% w/w (9.35 g/L), 33.6% (10.13 g/L), 33.3% (9.13 g/L), and 33.1% (9.03 g/L) w/w with the addition of 25, 50, 100, and 150 g/L glycerol, respectively. Glycerol concentration had little effect on lipid accumulation. However, glycerol concentration substantially affected increase of biomass concentration and cell count. The suitable glycerol concentration was approximately 40 g/L for Trichosporon oleaginosus growing in sludge medium with initial suspended solids (SS) concentration 30 g/L. Addition of nitrogen to sludge-glycerol medium enhanced lipid and biomass concentration. The energy conversion efficiency was 1.78, 1.55, and 1.71 with no nitrogen added, with addition of 1 g/L urea, and 3.7 g/L peptone, respectively. The biodiesel production cost was estimated nearly 0.75 US$/L.

Effect of Sludge Concentration and Crude Glycerol Matrix as a Substrate on the Production of Single-Cell Oil by Oleaginous Yeast Yarrowia lipolytica SKY7

“…Due to the increasing global population, the wastewater treatment sector is facing a monotonously increasing problem of an unmanageable volume of wastewater sludge for disposal. Different researchers have developed many different processes to valorize the nutritional components present in wastewater sludge to produce bioplastics, biodiesel, a biopesticide, and extra polysaccharides [3][4][5][6][7].…”

“…While biodiesel provides a green alternative to current existing petrochemical fuel resources, due to the expansion of the biodiesel industry, an increasing amount of crude glycerol, a waste product of the biodiesel industry, is also generated [1,8]. Researchers have also tried to valorize the crude glycerol generated by biodiesel industry to produce other value-added products [3,[7][8][9][10].…”

“…Recently, Zhang et al [7] attempted to solve these two problems by developing a process for the production of single-cell oil using Trichosporon oleaginosus. The study simultaneously used crude glycerol and municipal sludge as a source of carbon and other nutrients.…”

“…The study simultaneously used crude glycerol and municipal sludge as a source of carbon and other nutrients. Deriving the concept of the utilization of crude glycerol and sludge together from Zhang et al's [7] study, when the combination of crude glycerol and sludge solids were applied (without any further supplementation of minerals or other nutrients) to the yeast Yarrowia lipolytica SKY7, the fungal strain was strongly inhibited by the media. A bioreactor run (10 L working volume) was effectuated with 35 g/L of sludge suspended solids as nutrient media, and it was supplemented with the crude glycerol used in this study as a carbon source in fed-batch mode (data not presented).…”

Chemical and biological conversion of crude glycerol derived from waste cooking oil to biodiesel

“…The energy balance was calculated based on the mass balance study. In the energy balance study, assumptions were made: (1) the biodiesel production from crude glycerol took place in the biodiesel production industry (where crude glycerol was generated), which suggested that there was no energy input from the transportation of crude glycerol; (2) the energy input from the utilization of crude glycerol was zero and the crude glycerol generated in esterification and transesterification was also zero; (3) methanol and H 2 SO 4 were not recovered after esterification and remained in crude glycerol; (4) the fermentation of T. oleaginosus for lipid production was conducted under aseptic condition, the power consumption was adopted from our previous study (Zhang et al, 2017); (5) the energy input in biomass harvesting, lipid extraction and transesterification was similarly estimated as utilized in our previous study (Zhang et al, 2017); (6) in the trans-esterification of lipid to biodiesel, methanol and NaOH were not recovered after the reaction; (7) the cell debris was assumed to be used as animal feed (Zhang et al, 2016).…”