Abstract
Due to the health and environment impacts of fossil fuels utilization, biofuels have been investigated as a potential alternative renewable source of energy. Bioethanol is currently the most produced biofuel, mainly of first generation, resulting in food-fuel competition. Second generation bioethanol is produced from lignocellulosic biomass, but a costly and difficult pretreatment is required. The pulp and paper industry has the biggest income of biomass for non-food-chain production, and, simultaneously generates a high amount of residues. According to the circular economy model, these residues, rich in monosaccharides, or even in polysaccharides besides lignin, can be utilized as a proper feedstock for second generation bioethanol production. Biorefineries can be integrated in the existing pulp and paper industrial plants by exploiting the high level of technology and also the infrastructures and logistics that are required to fractionate and handle woody biomass. This would contribute to the diversification of products and the increase of profitability of pulp and paper industry with additional environmental benefits. This work reviews the literature supporting the feasibility of producing ethanol from Kraft pulp, spent sulfite liquor, and pulp and paper sludge, presenting and discussing the practical attempt of biorefineries implementation in pulp and paper mills for bioethanol production.
Highlights
The world depends on nonrenewable energy sources for transport, heat and/or power generation.Fossil fuels are currently the main energy source, providing an estimated 78.4% of the global final energy consumption [1]
There is a reduced operational complexity as configuration can result in a reduction of capital investment, since utilities that are associated with the three processes occur in a single vessel, consolidated bioprocessing (CBP) requires the development of engineered microbial enzyme production are eliminated
Kraft pulping, which is called sulfate process, corresponds to more than 95% of the chemical pulps produced [20] and consists on the reaction of an alkaline aqueous solution containing sodium hydroxide and sodium sulfide at high temperature (150–170 ◦ C) with lignin. When this solution contacts with wood chips, hydroxide and hydrosulfide anions react with lignin, which is partly degraded into phenolic fragments, whose dissolution removes almost 90% of the lignin from the wood
Summary
The world depends on nonrenewable energy sources for transport, heat and/or power generation. To the first generation, second generation bioethanol can be produced from residual biomass, such as forest, industrial, or municipal wastes These feedstocks do not raise concerns about food sustainability, have a low and stable price, and practically do not demand extra land. Integrated biorefineries could be implemented in the existing pulp and paper mills for the production of bioethanol from wastes and by-products generated. Since one of the major limitations for the production of second generation bioethanol is the high capital investment cost, by using the existing equipment of pulp and paper industry, the economics of the process could be improved, and its opportunity to success could increase [23,24]. The future conversion of pulp and paper mills into biorefineries will be addressed before future prospects and conclusions of this revision work
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
