PEER-REVIEWED REVIEW ARTICLE Hydrothermal Treatments Applied to Agro-and Forest- Industrial Waste to Produce High Added-Value Compounds AGRO-AND FOREST-INDUSTRIAL WASTE AS RAW MATERIAL FOR A BIOREFINERY (original) (raw)

Agro-and forest-industrial wastes are abundant and low cost sources of carbohydrates and phenolic compounds, which can be converted into biofuels, biomaterials, and high added-value compounds by different pathways in small and large biorefineries. The development of technologies based on hydrothermal treatments could improve the utilization of lignocellulosic wastes through the separation of its components (cellulose, hemicellulose, lignin, and extractives) in sequential processes. The adopted technologies for the separation and conversion of these lignocellulosic wastes into synthesis intermediates or products of high added value represent an important part of the total production cost. Low liquid to solid ratios and mild temperatures in the pre-treatment are interesting ways of reducing energy costs, subsequently economizing both steam and electricity. This work focuses on the advantages of using low liquid to solid ratios in the hydrothermal treatment of different agro-and forest-industrial wastes, paying particular attention to the performance of separation, purification, and conversion of hemicelluloses. Relevance of Agro-and Forest-Industrial Waste Biorefineries are analogous to petroleum refineries, which produce multiple fuels and products from petroleum, but instead use biomass as raw materials. Biorefinery technology is an alternative to the petroleum-based industry for energy, chemical, and material production from unconventional raw material. Given its renewable nature and low associated pollution, lignocellulosic biomass can be regarded as an important and sustainable source of carbohydrate (cellulose and hemicelluloses) fuel, cellulosic pulp, biomaterials, and a variety of chemicals. Lignocellulosic residues generated by the agro-industry are available in large quantities at low cost. The chemical, thermochemical, and biological conversions of this waste into its main components allow the production of chemical intermediates for the manufacture of various products. The use of forest and agricultural lignocellulosic residues as raw materials to generate high value added products is important because of their renewable nature and high availability (Area and Vallejos 2012).