This work presents an updated overview of waste lubricant oil (WLO) management practices in Europe to promote a circular economy. The characteristics of virgin and waste oil, their hazardous properties and the impacts of improper disposal are addressed. Current treatment routes and regeneration technologies adopted in Europe are presented. An overview of life cycle assessment (LCA) of WLO management strategies are summarized. Finally, future developments and concerns about the regeneration process are discussed. The current objectives of European Union toward a circular economy represent a challenge for Member States which must maximize the collection and recycling rates. EU management indicators show an overwhelming trend for recycling. However, there is a competition between recycling by regeneration to produce base oil and reprocessing for energy recovery. EU legislation states that priority should be given to options that provide better overall environmental outcome. However, LCA studies, are not unanimous about regeneration being the soundest environmental option. Other factors such as lubricant market, energy consumption, distance to treatment facilities, operation costs and product quality should be accounted for. Selective segregation of WLO is extremely important to increase the regeneration rate and obtain high-quality base-stocks. However, this means a significant increase in the collection costs.

Water resources are under pressure worldwide, resulting in scarcity and deterioration of freshwater quality. According to European directives, we could reduce the pressure on water resources in urban areas by increasing the reuse of treated wastewater, reducing the impact on water bodies, and promoting water recycling through multiple uses of urban wastewater. Besides the need to address water supply challenges, wastewater treatment systems show environmental stewardship and innovative practices. Using reclaimed water for agricultural irrigation is gaining interest because of the drought conditions experienced in Europe over the past few years. Furthermore, using treated wastewater for agricultural irrigation may help to restore nutrients (N and P) to natural biogeochemical cycles. This review highlights the importance of water reuse, current legislation, and existing technologies to implement in wastewater treatment systems to meet the minimum requirements to produce reclaimed water to reuse in agricultural irrigation.

The wine industry is one of the most relevant socio-economic activities in Europe. However, this industry represents a growing problem with negative effects on the environment since it produces large quantities of residues that need appropriate valorization or management. From the perspective of biorefinery and circular economy, the winery residues show high potential to be used for the formulation of new products. Due to the substantial quantities of phenolic compounds, flavonoids, and anthocyanins with high antioxidant potential in their matrix, these residues can be exploited by extracting bioactive compounds before using the remaining biomass for energy purposes or for producing fertilizers. Currently, there is an emphasis on the use of new and greener technologies in order to recover bioactive molecules from solid and liquid winery residues. Once the bio compounds are recovered, the remaining residues can be used for the production of energy through bioprocesses (biogas, bioethanol, bio-oil), thermal processes (pyrolysis, gasification combustion), or biofertilizers (compost), according to the biorefinery concept. This review mainly focuses on the discussion of the feasibility of the application of the biorefinery concept for winery residues. The transition from the lab-scale to the industrial-scale of the different technologies is still lacking and urgent in this sector.