Bioconversion of waste cooking oil glycerol from cabbage extract to lactic acid by Rhizopus microsporus

Abstract Glycerol from spent oil was processed by transesterification for biodiesel production. Although glycerol contains many types of impurities, it can be used as a C-source for lactic acid production by fungi, such as Rhizopus microsporus. In this study, we found that wild type R. microsporus (LTH23) produced more lactic acid than the mutant strains on cabbage glycerol media (CG media). More lactic acid was produced on CG media than on cabbage extract media (C media) by about two-fold in batch fermentation conditions. In addition, we found that lactic acid production in a fed-batch process was also slightly higher than in a batch process. To study the combined effects of pH, urea, and glycerol waste concentration on lactic acid production, a response surface methodology was used. The optimum pH, urea, and glycerol waste concentrations were pH 6.5, 3.75 g/L, and 17 g/L, respectively. The maximum lactic acid production predicted by this equation model was 4.03 g/L.

Bioconversion of waste cooking oil glycerol from cabbage extract to lactic acid by Rhizopus microsporus

Abstract Glycerol from spent oil was processed by transesterification for biodiesel production. Although glycerol contains many types of impurities, it can be used as a C-source for lactic acid production by fungi, such as Rhizopus microsporus. In this study, we found that wild type R. microsporus (LTH23) produced more lactic acid than the mutant strains on cabbage glycerol media (CG media). More lactic acid was produced on CG media than on cabbage extract media (C media) by about two-fold in batch fermentation conditions. In addition, we found that lactic acid production in a fed-batch process was also slightly higher than in a batch process. To study the combined effects of pH, urea, and glycerol waste concentration on lactic acid production, a response surface methodology was used. The optimum pH, urea, and glycerol waste concentrations were pH 6.5, 3.75 g/L, and 17 g/L, respectively. The maximum lactic acid production predicted by this equation model was 4.03 g/L.

Progress and prospect of bio-jet fuels industry in domestic and overseas / 生物工程学报

We reviewed the progress of the bio-jet fuels industry in recent years and systematically analyzed the technical routes that have been approved or in the pipeline for approval by ASTM D7566. In addition, we highlighted a novel pathway to produce drop-in fuel by near-critical hydrolysis of waste cooking oils or algal oils followed by catalytic decarboxylation. Also, we introduced the source of oils and fats feedstock and the domestic bio-jet fuel industry status during the 12th Five-Year-Plan period. Based on our own research, we discussed the prospect of the bio-jet fuel industry and future research needs.

Microbial conversion of waste cooking oil into riboflavin by Ashbya gossypii / Conversão microbiana de óleo de cozinha recolhido em riboflavina por Ashbya gossypii

The conversion of waste cooking oil into riboflavin by Ashbya gossypii was investigated in this paper. The effect of initial pH and the original volume of added waste cooking oil in the medium were evaluated to optimize the fermentation efficiency. The results show that when the initial pH was adjusted to 6.5 and 40 g/L waste cooking oil was added in the medium, no residual waste cooking oil was observed and the riboflavin yield reached 4.78 g/L. During the fermentation process, pH, biomass, free amino nitrogen and reduced sugar were dynamically monitored to evaluate the efficient utilization of waste cooking oil for riboflavin yield. The results show that when pH was kept in the range of 6.5-6.8 during the fermentation process, the levels of free amino nitrogen and reduced sugar could be used more efficiently and the riboflavin yield increased to 6.76 g/L .

A conversão microbiana de óleo de cozinha recolhido em riboflavina por Ashbya gossypii foi investigada nesse estudo. O efeito inicial do pH e o volume original de óleo de cozinha recolhido foram avaliados para otimizar a eficiência de fermentação. Os resultados mostraram que quando o pH inicial foi ajustado para 6.5 e 0g/l de óleo de cozinha adicionado ao meio, nenhum óleo residual foi observado e a riboflavina pura atingiu 4.78g/L. Durante o processo de fermentação, pH, biomassa, amino nitrogênio livre e açúcar reduzido foram monitorados dinamicamente para avaliar a utilização eficiente do óleo de cozinha recolhido por riboflavina. Os resultados mostram que quando o pH é mantido numa amplitude de 6.5-6-8 durante o processo de fermentação, os níveis de amino nitrogênio livres e açúcar reduzido podem ser usados mais eficientemente e a riboflavina pura chega a 6.76 g/L.

Statistical Optimization of Process Variables for Biodiesel Production from Waste Cooking Oil Using Heterogeneous Base Catalyst.

In this study, the effects of methanol-to-oil molar ratio, catalyst amount and reaction time on the transesterification of waste cooking oil (WCO) to biodiesel were investigated. Methanol with calcium oxide as a heterogeneous catalyst was used for the transesterification process at a temperature of 60oC and 3000 rpm stirring speed. Response surface methodology (RSM) with central composite rotable design (CCRD) was used at five levels of oil-to-methanol molar ratio (9:1 – 14:1), catalyst (1- 5 %) and reaction time (30 – 90 min) as independent variables and WCO biodiesel yield as dependent variable (response). A statistically significant (P < 0.0001) second-order quadratic polynomial regression model with a coefficient of determination, R (= 0.9964) was obtained for biodiesel production (using Design-Expert Statistical program (v. 6.0.8)) and verification experiment confirmed the validity of the predicted model. Numerical optimization technique based on desirability function was carried out to optimize the WCO conversion to biodiesel. The optimum combinations for transesterification to achieve a predicted maximum biodiesel yield of 94.15 percent were found to be: oil-to-methanol molar ratio, 9.14:1; catalyst amount, 3.49 % and reaction time, 60.49 min. At this optimum condition, the observed biodiesel yield was found to be 94.10 percent. In addition, the fuel properties of the produced biodiesel were in the acceptable ranges according to international standards for biodiesel specifications. The statistical analyses and the closeness of the experimental results to model predictions show the reliability of the regression model and thus, the results will be helpful in selecting an efficient and economical method for biodiesel production from cheap raw materials with high free fatty acid.

Waste cooking oil as substrate for biosynthesis of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): Turning waste into a value-added product

Aims: Improper disposal of domestic wastes, such as waste cooking oil (WCO), contributes to the deterioration of the environment and may lead to health problems. In this study, we evaluated the potential of plant-based WCO as a carbon source for the commercial biosynthesis of the bio-plastics, poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). The consumption of WCO for this purpose would mitigate their pollution of the environment at the same time. Methodology and Results: WCO collected from several cafeterias in USM was tested as the carbon source for polyhydroxyalkanoates (PHA) production. A selection of suitable nitrogen source was first conducted in order to obtain an acceptable number of dry cell weight (DCW) and PHA content. Urea was found to be a suitable nitrogen source for the two bacterial strains used in our study, Cupriavidus necator H16 and its transformed mutant, C. necator PHB¯4 harboring the PHA synthase gene of Aeromonas caviae (PHB¯4/pBBREE32d13). With WCO as the sole carbon source, C. necator H16 yielded a relatively good dry cell weight (DCW=25.4 g/L), with 71 wt% poly(3-hydroxybutyrate) P(3HB) content. In comparison, the DCW obtained with fresh cooking oil (FCO) was 24.8 g/L. The production of poly(3 hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from WCO by the transformant C. necator PHB¯4 was comparable, yielding a DCW of 22.3 g/L and P(3HB-co-3HHx) content of 85 wt%. Lipase activities for both bacterial strains reached a maximum after 72 h of cultivation when time profile was conducted. Conclusion, significance and impact of study: The use of WCO as a carbon source in the biosynthesis of the bioplastic, PHA, turns a polluting domestic waste into a value-added biodegradable product. This renewable source material can thus be exploited for the low cost production of PHA.