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

Abstract

In this study, crude, purified, and pure glycerol were used to cultivate Trichosporon oleaginosus for lipid production which was then used as feedstock of biodiesel production. The purified glycerol was obtained from crude glycerol by removing soap with addition of HPO which converted soap to free fatty acids and then separated from the solution. The results showed that purified glycerol provided similar performance as pure glycerol in lipid accumulation; however, crude glycerol as carbon source had negatively impacted the lipid production of T. oleaginosus. Purified glycerol was later used to determine the optimal glycerol concentration for lipid production. The highest lipid yield 0.19g/g glycerol was obtained at 50g/L purified glycerol in which the biomass concentration and lipid content were 10.75g/L and 47% w/w, respectively. An energy gain of 4150.51MJ could be obtained with 1tonne of the crude glycerol employed for biodiesel production through the process proposed in this study. The biodiesel production cost estimated was 6.32US$/gal. Fatty acid profiles revealed that C16:0 and C18:1 were the major compounds of the biodiesel from the lipid produced by T. oleaginosus cultivated with crude and purified glycerol. The study found that purified glycerol was promising carbon source for biodiesel production.

Energy balance for biodiesel production processes using microbial oil and scum

“…The difference is just that instead of glucose, purified crude glycerol is used for fermentation and micro-organism used for lipid production is T. oleaginosus. The fermentation has been considered from Chen et al (2018a) where 85% phosphoric acid was used for purifying crude glycerol through precipitation. The purified crude glycerol used during fermentation had (w/w) composition of 55% glycerol, 1.5% biodiesel, 4.2% ash, 18.5% methanol and 20.8% water.…”

“…Moreover, studies have been reported on the energy balance for biodiesel production from microbial oil using co-fermentation of crude glycerol and wastewater sludge (Chen et al, 2018a;Zhang et al, 2013;Zhang et al, 2016). However, those studies were done considering traditional downstream operations for biomass settling and lipid extraction.…”

“…Along with these steps, biomass needs to be dried before cell wall disruption. These steps are energy intensive and therefore necessitates to look for alternatives (Chen et al, 2018a;Zhang et al, 2017). Recently in INRS lab, biomass settling has been performed using chemical coagulant, Calcium chloride and bio-flocculant (extra-polymeric substances or EPS) that will eliminate the requirement of centrifugation.…”

Optimization of trace elements in purified glycerol for microbial lipid and citric acid production by Yarrowia lipolytica SKY7

“…These impurities may inhibit cell growth and lipid production depending on the stain and concentration of the impurity [10]. Acidification is an effective method to remove soap, metals and salts from the crude glycerol [2,10,19]. However, purified glycerol obtained after acid treatment may contain several trace elements required for microbial growth, but they may not be present in sufficient concentration needed for lipid and citric acid production or they may not be consumed by microbe.…”

Desarrollo de catalizadores sólidos ácidos para la eterificación de glicerol obtenido en la producción de biodiésel

“…El interés por el desarrollo de aplicaciones para el glicerol crudo se debe a dos razones, una de ellas, el aumento de la oferta de este compuesto generado por la industrial del biodiésel, la otra se funda en los elevados costos del proceso de purificación que se trasladan a la materia prima . El exceso de glicerol puede afectar negativamente el mercado del biodiésel por eso se buscan alternativas de uso directo de este subproducto o tratamientos de purificación parcial (Chen et al, 2018) (Hejna, Kosmela, Formela, Piszczyk, & Haponiuk, 2016).…”