Gate-to-gate life cycle assessment of biosurfactants and bioplasticizers production via biotechnological exploitation of fats and waste oils

BACKGROUND: This study investigated the biotransformation of fats and waste oils towards glycolipid biosurfactants and bioplasticizers. The ecological performance and environmental impacts of the bioprocesses were evaluated aiming to assess their present environmental status and thus suggest future improvements using LCA methodology. RESULTS: Biosurfactants, namely rhamnolipids and sophorolipids were obtained via fermentation. Bioplasticizers, Fatty Acid Ethyl Esters (FAEE) and Monoglycerides (MAG), were developed via enzymatic catalysis with selected enzymes in mesophilic temperatures via ethanolysis and glycerolysis, respectively. The study revealed that air emissions, electricity and thermal energy requirements are the key contributors to the potential environmental impacts in the LCIA. More specifically, rhamnolipids production has less energetic needs compared to sophorolipids manufacturing, resulting thus to lower environmental impacts. The increased thermal requirements of MAG production phase is the main contributor to their negative environmental performance, with the overall energy consumption for MAG production being 3-fold higher than the FAEE formation phase. CONCLUSIONS: The assessment identified that among the biosurfactant production processes, the sophorolipids production resulted to 22.7% higher environmental impact compared to rhamnolipids. Similarly, FAEE production can be classified as a more environmental friendly process compared to MAG, resulting to 67% lower environmental impact based on the environmental indicators assessed

Two-stage anaerobic digestion harnesses more energy from the co-digestion of end-of-life dairy products with agro-industrial waste compared to the single-stage process

This research aimed at comparing the single-stage and two-stage co-digestion of end-of-life dairy products (EoL-DPs) with a mixture of agro-industrial waste(water)s. The two systems were operated in parallel and operational parameters including hydraulic retention time (HRT) and organic loading rate were tested for their effect on biohydrogen and bio-methane production. During acidogenic fermentation of EoL-DPs, HRT of 3 days led to process instability due to lactate accumulation, whereas HRT of 6 days resulted in maximum hydrogen yield of 0.676 mol H-2 mol(-1) carbohydrates consumed. Slaughterhouse waste pasteurization did not significantly affect the anaerobic digestion (AD) process, while the increased EoL-DPs feeding ratio enhanced methane yield in both systems (34.7-37.6% increase). Interestingly, the high ammonia concentration (c.a. 4 g L-1) did not inhibit AD. The energy productivity of the two-stage system was roughly 30% higher, and therefore is the suggested approach for agro-industrial waste(water) valorization