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Reusing reclaimed asphalt pavements (RAPs) provides economic, social, and environmental benefits. To improve the performance of these materials, rejuvenating agents such as waste cooking oil (WCO) have been implemented. The annual amounts of RAP and WCO available in the Área Metropolitana de Bucaramanga (AMB) were calculated to be 32 thousand and 22 thousand tons per year, respectively. Subsequently, international standards were reviewed and compared with Colombian regulations to establish a methodology to determine the appropriate percentage of WCO to add to RAP for hot asphalt mix preparation. The authors suggest investigating WCO levels from 3% to 6% and selecting the percentage that reestablishes the penetration grade (INV-E-706-13), softening point (INV-E-712-13), and viscosity (INV-E-717 -13) of asphalt binder. For hot asphalt mix preparation, the authors propose using the Marshall method and determining the appropriate percentage of asphalt according to stability and flow tests (INV-E-748-13), percent air voids (INV-E-736-13), and bulk density (INV-E-733-13).3).

The present study investigated the potential lipase production for Bacillus licheniformis SMIA-3 using the agro-industrial co-products: orange flour (OF) and grape flour (GF) blend waste cooking oil (WCO). The OF was selected due to its best source for lipase production observed in preliminary tests. Therefore, OF was tested at different fermentation times at 50°C using the statistical design Central Composite Rotatable Design (CCRD) allied to the response surface. An optimal region was found with lipolytic activity of 0.349 U mL-1 with OF and WCO filters around (0.50% w v-1) and between (0.55 and 0.75% w v-1), respectively, and the fermentation time at the central point (42h). Data supplied a method to produce lipase using orange flour and frying oil, as a way to reuse these waste as feedstock to obtain employable lipase and lower production costs with biotechnological applications in industrial sector

This study presents a take on employing the principles of waste valorization to solve the long-standing problem of finding sustainable resources for biodiesel production. The biodiesel production has always met with a competition with food security and land use. This has limited the scope of the technology to laboratory experiments only. This study aims to assess the geospatial availability of waste cooking oil in Pakistan to map its biodiesel production potential. Owing to the resource posing no land use or food security challenges, a resource assessment using geographical information systems was carried out. The waste cooking oil availability was estimated using the statistics on per capita edible oil consumption with a realistic consumption and collection factor applied to it. The available residual cooking oil was subjected to the transesterification with a rather conservative conversion to the biodiesel at 66.25% to keep the estimates realistic. The study results in heat maps of all the different regions and provinces of the country. The findings suggest that Punjab province is the highest potential province with 249,260 tonnes of biodiesel production annually. Karachi district is the highest potential district with a potential of 36,156 tonnes of biodiesel production in a year. The study paves ways for investment sector in the study area to identify highest potential regions to invest in. It also motivates the scientific community to step outside of experimental research on waste cooking oil’s biodiesel production potential and perform resource assessments and techno-economic analyses on the technology for its widespread adoption. Graphic abstract PS—The callouts do not represent any geographical locations instead they represent the shade of the gradient they correspond to in terms of red being the gradient shade for the problems and the green being the gradient shade for the remedial contributions made by the study. The use of the map of the study area is because of the contextual important of the map in a resource and potential assessment that is geospatial in nature.

The identification and quantification of free fatty acids (FFA) in edible and non-edible vegetable oils, including waste cooking oils, is a crucial index to assess their quality and drives their use in different application fields. NMR spectroscopy represents an alternative tool to conventional methods for the determination of FFA content, providing us with interesting advantages. Here the approaches reported in the literature based on 1H, 13C and 31P NMR are illustrated and compared, highlighting the pros and cons of the suggested strategies.

Polyhydroxyalkanoate (PHA) is an important bioplastic, its production has been commercialized, and an increase of production capacities is expected. As with many other basic chemicals, PHA production requires a currently unavailable amount of renewable carbon if bioplastic production is ever to compete with plastic production from petroleum. This extensive demand for raw materials poses challenges in terms of costs, logistics, and land use. The application of biogenic residues is therefore one of the prerequisites for any economically significant and environmentally friendly PHA production. Against this background, recent findings on the possibilities of using biogenic residues from food production and consumption to produce PHA are summarized. Waste animal fats, waste cooking oil, but also mixed food waste, either from food production or consumer food waste represent the most abundant food-related residues. They are explored for their potential to serve as substrate for PHA production. While waste animal fat and waste cooking oil can be fed directly into suspension cultures, mixed food waste can be converted into short-chain carboxylic acids from microbial hydrolysis and acidogenesis in dark fermentation before being fed. Titers and productivity of the several feedstock options are compared. The potential for economically viable and sustainable production and integration into local material cycles is highlighted, although there are still several challenges to overcome. Key points • Waste cooking oil enables low-cost and scalable PHA production • Thermally liquefied animal fats are a suitable feed for emulsifier-free PHA production • Coupling dark fermentation and PHA production is economically feasible • The impact of carboxylic acid composition on PHA synthesis is explored

A detailed review was conducted to explore waste cooking oil (WCO) as feedstock for biodiesel. The manuscript highlights the impact on health while using used cooking oil and the scope for revenue generation from WCO. Up to a 20% blend with diesel results in less pollutants, and it does not demand more modifications to the engine. Also, this reduces the country’s import bill. Furthermore, it suggests the scope for alternate sustainable income among rural farmers through a circular economy. Various collection strategies are discussed, a SWOC (strength, weakness, opportunity, and challenges) analysis is presented to aid in understanding different countries’ policies regarding the collection of WCO, and a more suitable method for conversion is pronounced. A techno-economic analysis is presented to explore the viability of producing 1 litre of biodiesel. The cost of 1 litre of WCO-based biodiesel is compared with costs Iran and Pakistan, and it is noticed that the difference among them is less than 1%. Life cycle assessment (LCA) is mandatory to reveal the impact of WCO biodiesel on socio-economic and environmental concerns. Including exergy analysis will provide comprehensive information about the production and justification of WCO as a biodiesel.

Background Limonene is an important biologically active natural product widely used in the food, cosmetic, nutraceutical and pharmaceutical industries. However, the low abundance of limonene in plants renders their isolation from plant sources non-economically viable. Therefore, engineering microbes into microbial factories for producing limonene is fast becoming an attractive alternative approach that can overcome the aforementioned bottleneck to meet the needs of industries and make limonene production more sustainable and environmentally friendly. Results In this proof-of-principle study, the oleaginous yeast Yarrowia lipolytica was successfully engineered to produce both d-limonene and l-limonene by introducing the heterologous d-limonene synthase from Citrus limon and l-limonene synthase from Mentha spicata, respectively. However, only 0.124 mg/L d-limonene and 0.126 mg/L l-limonene were produced. To improve the limonene production by the engineered yeast Y. lipolytica strain, ten genes involved in the mevalonate-dependent isoprenoid pathway were overexpressed individually to investigate their effects on limonene titer. Hydroxymethylglutaryl-CoA reductase (HMGR) was found to be the key rate-limiting enzyme in the mevalonate (MVA) pathway for the improving limonene synthesis in Y. lipolytica. Through the overexpression of HMGR gene, the titers of d-limonene and l-limonene were increased to 0.256 mg/L and 0.316 mg/L, respectively. Subsequently, the fermentation conditions were optimized to maximize limonene production by the engineered Y. lipolytica strains from glucose, and the final titers of d-limonene and l-limonene were improved to 2.369 mg/L and 2.471 mg/L, respectively. Furthermore, fed-batch fermentation of the engineered strains Po1g KdHR and Po1g KlHR was used to enhance limonene production in shake flasks and the titers achieved for d-limonene and l-limonene were 11.705 mg/L (0.443 mg/g) and 11.088 mg/L (0.385 mg/g), respectively. Finally, the potential of using waste cooking oil as a carbon source for limonene biosynthesis from the engineered Y. lipolytica strains was investigated. We showed that d-limonene and l-limonene were successfully produced at the respective titers of 2.514 mg/L and 2.723 mg/L under the optimal cultivation condition, where 70% of waste cooking oil was added as the carbon source, representing a 20-fold increase in limonene titer compared to that before strain and fermentation optimization. Conclusions This study represents the first report on the development of a new and efficient process to convert waste cooking oil into d-limonene and l-limonene by exploiting metabolically engineered Y. lipolytica strains for fermentation. The results obtained in this study lay the foundation for more future applications of Y. lipolytica in converting waste cooking oil into various industrially valuable products.

Vegetable oils have been used as a feedstock for fatty acid methyl ester (FAME) production. The high cost of neat vegetable oil and its impact on food security have necessitated its replacement as a feedstock for FAME by used vegetable oil, also known as waste cooking oil (WCO). This study compares the properties and fatty acid (FA) compositions of samples of neat vegetable oil with those of samples of WCO, collected from restaurants and takeaway outlets at the point of disposal. The samples were subjected to property determination and pyrolysis gas chromatography mass spectrometer (PYGCMS) analysis. Analysis showed that degree of usage and the type of food items originally fried in the oil substantially affected its properties and FA composition. Density of neat vegetable oil varied between 904.3 and 919.7 kg/m3 and of WCO between 904.3 and 923.2 kg/m3. The pH of neat vegetable oil varied between 7.38 and 8.63 and of WCO between 5.13 and 6.61. The PYGCMS analysis showed that neat palm oil contains 87.7% unsaturated FA and 12.3% saturated FA, whereas neat sunfoil contains 74.37% saturated FA and 25% polyunsaturated FA. Generally, neat vegetable oils consisted mainly of saturated FAs and polyunsaturated FAs, whereas the WCO contained mainly of saturated FAs and monounsaturated FAs. This research confirms the suitability of WCO as feedstock for FAME.

As non-renewable conventional fossil fuel sources are depleting day by day, researchers are continually finding new ways of producing and utilizing alternative, renewable, and reliable fuels. Due to conventional technologies, the environment has been degraded seriously, which profoundly impacts life on earth. To reduce the emissions caused by running the compression ignition engines, waste cooking oil (WCO) biodiesel is one of the best alternative fuels locally available in all parts of the world. Different study results are reviewed with a clear focus on combustion, performance, and emission characteristics, and the impact on engine durability. Moreover, the environmental and economic impacts are also reviewed in this study. When determining the combustion characteristics of WCO biodiesel, the cylinder peak pressure value increases and the heat release rate and ignition delay period decreases. In performance characteristics, brake-specific fuel consumption increases while brake-specific energy consumption, brake power, and torque decrease. WCO biodiesel cuts down the emissions value by 85% due to decreased hydrocarbon, SO2, CO, and smoke emissions in the exhaust that will effectively save the environment. However, CO2 and NOx generally increase when compared to diesel. The overall economic impact of production on the utilization of this resource is also elaborated. The results show that the use of WCO biodiesel is technically, economically, environmentally, and tribologically appropriate for any diesel engine.

The increasing generation of waste cooking oil (WCO) poses significant environmental challenges, making its valorization essential for sustainable waste management. This research investigates the in situ peracid method for epoxidizing a hybrid mixture of oleic acid and waste cooking oil. A novel approach is proposed by utilizing hybrid raw materials in the presence of natural zeolite as a catalyst to enhance epoxidation efficiency. The signal-to-noise (S/N) ratio analysis in Taguchi method showed that the optimum process parameters for production of epoxidized hybrid oleic acid and waste cooking oil to the response of relative conversion to oxirane (RCO) with determination of oxirane oxygen content (OOC) was maximum (50%) under following conditions: temperature of 50 °C, stirring at 100 rpm, and a molar ratio 1:1 with formic acid. After 100 iterations, the reaction rate constant based on optimized epoxidized hybrid oleic acid and waste cooking oil production was obtained as follows: k 11  = 13.45 mol⋅L −1 ⋅min −1 , k 12  = 14.08 mol⋅L −1 ⋅min −1 , k 2  = 0.023 mol⋅L −1 ⋅min −1 , and k 3  = 0.025 mol⋅L −1 ⋅min −1 .This discovery helps reduce waste, turns used cooking oil into a valuable commodity, and offers insight into reaction kinetics, a critical concept for industrial applications that is environmentally friendly.