Hydrothermal treatment of oleaginous yeast for the recovery of free fatty acids for use in advanced biofuel production

Incorporation of Biosolids as Water Replacement in a Two-Step Renewable Hydrocarbon Process: Hydrolysis of Brown Grease with Biosolids

ABSTRACT

The accumulating volumes of biosolids in lagoons worldwide have intensified the need to develop innovative wastewater treatment strategies. Here, we provide proof-of-concept for the incorporation of biosolids into the hydrolysis step of a two-step thermal conversion of lipids for production of renewable hydrocarbons, which can be utilized as renewable fuels. Brown grease was hydrolysed with biosolids or water at 260-280 °C for 60 min at a mass ratio of 1:1 feed to water or biosolids. The feedstock and products were characterized using various analytical techniques to compare the performance of biosolids to water. The results indicated that there was no significant difference in the degree of hydrolysis of brown grease when biosolids was used as water replacement. The fatty acids composition after hydrolysis when biosolids was used as a water replacement also remained largely unchanged. Hydrolysis of brown grease with biosolids could be achieved at pH ranging from 3.3 to 8.9, and at a lower than previously established temperature. Significantly, the rapid settling of solid material in biosolids observed after thermal hydrolysis of brown grease may reduce the necessity of biosolids settling lagoons. Thus, incorporation of biosolids into a lipid hydrolysis-pyrolysis process may simultaneously benefit the biofuel and waste management sectors.

Microbial oil - A plausible alternate resource for food and fuel application

Microbes have recourse to low-priced substrates like agricultural wastes and industrial efflux. A pragmatic approach towards an emerging field- the exploitation of microbial oils for biodiesel production, pharmaceutical and cosmetic applications, food additives, biopolymer production will be of immense remunerative significance in the near future. Due to high free fatty acid, nutritive content and simpler solvent extraction processes of microbial oils with plant oil, microbial oils can back plant oils in food applications. The purpose of this review is to evaluate the opulence of lipid production in native and standard micro-organisms and also to emphasize the vast array of applications including food and fuel by obtaining maximum yield.

Simultaneous production of proteases and antioxidant compounds from agro-industrial by-products

The use of processes for simultaneous production of bioproducts as enzymes and bioactive compounds is an interesting alternative to reduce environmental impacts. Thus, the aim of this study was to produce simultaneously, using the biorefinery concept, both proteases and bioactive compounds with antioxidant activity from Bacillus sp. P45 cultivation by using different by-products. The integrated process developed in this study enabled to obtain enzymes with proteolytic and keratinolytic properties in a process with alternate substrates from agro-industrial by-products (feather meal, residual feather meal and biomass), thus, creating an interesting alternative to managing them. The residual biomass provided the highest protease activity (1306.6U/mL) and the reused feather meal reached the highest keratinolytic activity (89U/mL), both at 32h of cultivation. Moreover, hydrolysates produced in cultivation using feather meal and residual biomass had high antioxidant activity, they have great potential as natural antioxidants.

Cultivation of oleaginous yeast using aqueous fractions derived from hydrothermal pretreatments of biomass

This study addresses some of the current challenges in producing biofuels from yeast oils. Specifically, it valorizes byproduct waste streams of biomass processing technologies by integrating them as alternative carbon or nutrient sources in oleaginous yeast cultivation. Crude glycerol recovered from the thermal hydrolysis of various fats and oils was successfully used in culturing of the oleaginous yeast Cryptococcus curvatus, with growth and lipid accumulation occurring at levels identical to those achieved when commercially purchased glycerol was used. The aqueous byproduct stream from the hydrothermal processing of C. curvatus can also be recycled as a growth substrate for subsequent C. curvatus cultures. The addition of this stream promoted higher biomass production without affecting lipid accumulation and only moderately changing the fatty acid profile. Use of these recycling strategies reduces costs and environmental impact of current microbial biofuels production by providing accessible, non-expensive carbon sources and nutrients for oleaginous yeast cultivation.