Conversion of residues and by-products from the biodiesel industry into value-added products

Biodiesel, one of the most important sources of renewable energy, is produced in large quantities around the world; however, its production generates different kinds of residues and by-products which raise economic and environmental concerns. This review presents a compilation of the data on current state of transformation of residues and by-products of biodiesel industry into products that are suitable for bio-refining. The review has analyzed glycerol, biodiesel washing wastewaters, and solid residues. The technologies were described and the most significant experimental results and variables were summarized to allow researchers an easy access to this information. © 2016, The Author(s).