The management of waste cooking oil (WCO) often poses significant challenges. Improper disposal of WCO results in negative environmental impacts and economic losses. However, from a circular economy perspective, WCO can be recycled and used as a sustainable feedstock for numerous industrial products, replacing virgin vegetable oils. This approach enables the recovery of resources while simultaneously addressing the problem of WCO disposal. By employing a multi-criteria decision analysis (MCDA) approach, the study assesses three alternative recycling pathways for WCO used as a feedstock in the production of A1) biodiesel, A2) biolubricant, and A3) biosurfactant. The aim is to identify the optimal alternative, taking into account environmental, economic, and technical factors. The procedure involved a team of chemical engineers working in the WCO recycling sector who were selected as decision-makers. The 'priority scale' combined with the Paired Comparison Technique was employed as a weighting method to evaluate the selected criteria. The results revealed that the decision-makers considered environmental sustainability as the most crucial evaluation criterion, followed by the economic criterion. In contrast, the aspect of process management was deemed less significant. Among the compared alternatives, utilizing WCO as a feedstock for biosurfactant production was assessed as the optimal WCO recycling solution. This alternative not only demonstrated the lowest coefficient variation but was also deemed the most favourable option. Biolubricant production was determined to be the second-best alternative. The adopted MCDA approach proved to be a reliable and effective tool, enabling the clear identification of the preferred WCO recycling alternative among those assessed. This was achieved through the utilization of the decision-makers' expertise and knowledge.

The contamination of aquatic environments by pharmaceutical products consistently takes the attention of researchers due to the compounds' toxicity even at low concentrations. In response, we have developed an ecologically sustainable biosurfactant derived from a microorganism and incorporated into the bacterial cellulose. This bioproduct, along with the bacterial cellulose itself, was employed as a sorbent for pharmaceuticals (hormones and paracetamol) present in water. Bacterial cellulose membranes were generated through the cultivation of Gluconacetobacter xylinus ATCC 53582. The biosurfactant was produced by pre-inoculating Bacillus subtilis in a synthetic medium, followed by immersing the bacterial cellulose membranes in the biosurfactant solution, for incorporation. Tests were conducted using water experimentally contaminated with parace-tamol and 17α-ethinylestradiol (EE2), evaluating the biosurfactant's effect on bacterial cellulose sorption. Paracetamol levels were analyzed using spectrophotometry, and EE2 levels were as-sessed using high-performance liquid chromatography. In summary, bacterial cellulose exhibited superior adsorption for EE2 compared to paracetamol. The incorporation of biosurfactant onto bacterial cellulose reduced hormone adsorption but enhanced paracetamol sorption. Our findings indicated that adsorption is more effective with bacterial cellulose in its original and freeze-dried forms, without the incorporation of biosurfactant. Notably, we achieved more promising results in remediating the hormone EE2 compared to the paracetamol.

Background: Biosurfactants are amphiphilic surface active compounds that produced by several microorganisms, including, bacteria and fungi. Biodegradability, low toxicity, applications diversity and functionality under extreme conditions are characterized them from chemically biosurfactants. It is found that, Rhodotorula species, read yeasts, have high potency for biosurfactant producing. Recently, antimicrobial activities of biosurfactants have been subjected for new antibiotic therapy. The aim of the present study was to evaluate biosurfactant production by the different strains of Rhodotorula species in laboratory conditions. In addition, antifungal activity of produced biosurfactant was assessed against several saprophytic fungi. In the present study 54 strains of Rhodotorula including, R. glutinis (48 strains), R. minuta (2 strains), R. mucilaginosa (2 strains) and Rhodotorula species (2 strains) were screened for biosurfactant production. The biosurfactant was produced using the Sabouraud dextrose broth medium and confirmed by specific tests. Antifungal assay was also evaluated by disk diffusion method and the serial dilutions of biosurfactant. In the present study, although all tested strains were capable to produce biosurfactant in vitro, the degree of biosurfactant production was varied among stains. 7.4% strains had the highest (+5) biosurfactant activity followed by 16.7%, 29.5%, 25.8% and 20.4% had +4, +3, +2 and +1, respectively. In the present study, all tested fungi were inhibited at 40 µl of biosurfactant. Rhodotorula species are appropriate organisms for the production of biosurfactants and R. glutinis strains have the greatest ability to producing biosurfactant than another species. Furthermore, our results were demonstrated that the produced biosurfactant by R. glutinis presented a valuable potential for biopharmaceutical applications.