Oleaginous yeast biomass flocculation using bioflocculant produced in wastewater sludge and transesterification using petroleum diesel as a co-solvent

摘要

In this research a new process of harvesting the oleaginous yeast biomass (Yarrowia lipolytica) by flocculation followed by cell wall disruption and lipid extraction with petroleum diesel as a solvent was developed. Alum and calcium chloride along with the extracellular polymeric substance (EPS) as a flocculant were evaluated for lipid bearing biomass settling. The maximum flocculation activity of biomass using calcium chloride (36 mM) in combination with EPS (5.85 mg EPS/g biomass) or Alum (1.2 mM) with EPS (18 mg EPS/g biomass) was 74.3 and 79% and the settling velocity was 2.93 and 1.46 mm/s, respectively. To have a similar efficiency of biomass settling, 3.07 times less dosage of EPS was required in combination with calcium chloride than required with Alum. Further, settled biomass (166 g/L) was treated with N-lauroyl sarcosine (N-LS) to disrupt the cellular structure and release lipid. The released lipid was separated from cell debris and water using petroleum diesel (co-solvent) and maximum lipid recovery efficiency of 94.7 +/- 1.2 % (w/w) was observed. (C) 2018 Elsevier Ltd. All rights reserved.