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.

Kraft pulp mills produce the main raw material for paper, while several waste products are generated in large quantities in the process. This review study addresses four of the main inorganic wastes formed by this industry, namely green liquor dregs (GLD), slaker grits (SG), lime mud (LM) and boiler fly ash (BFA), which are still mostly discarded in landfills. A brief overview of a typical industrial process was included to outline the waste generation points. The main chemical and physical properties are indicated for highlighting the most relevant characteristics to determine which applications may be considered in each case. An in-depth literature review allowed the identification of the main applications that have been tested mainly at the laboratory scale and some at an industrial scale. The applications are grouped into construction materials, geotechnical, environmental, agricultural and others. This assessment shows that the circular economy and the sustainable development goals of the UN are important issues for organizations in general, and the pulp mill in particular. In fact, this industry has managed to close the chemicals loops, recover energy and reduce water consumption in the process. However, the current situation of inorganic waste can still be improved if industrial applications are developed to avoid landfill.