VALORIZATION OF RESIDUES FROM AGRICULTURAL AND FOOD INDUSTRIES TOWARDS BIOFUELS AND BIOPRODUCTS USING BIOCHEMICAL AND THERMOCHEMICAL TECHNOLOGIES

The large volumes of organic waste streams produced daily as a part of our food and water supply systems create a global management challenge. Traditionally, these wastes are landfilled, composted, or used for the production of animal feed and fertilizers. However, the majority of this waste has a high potential for recovery of valuable bio-based products. Hydrothermal processes are well suited for the valorization of wet organic waste. Hydrothermal liquefaction (HTL) is performed at temperatures ranging 250-350˚C and high pressures to exploit the special properties of hot liquid water. HTL yields a bio-crude oil, hydro-char, water-soluble compounds, and gas. These phases have the potential to be used as “building blocks” for the production of fuels and bio-products. In this project, valorization of representative wastes: from food production (wine, apple cider, beer, and olive oil production), dairy industry (manure and whey), and wastewater treatment plant were screened at different temperatures, reaction times, and pH conditions. Carbon balances gave information about the influence of the raw material and reaction conditions in directing carbon to any of the four HTL products (i.e., char, oil, water and gas). In the HTL of cow manure, higher temperatures and longer residence times favored the concentration of carbon from raw material into the oil phase (15%wt C at 250˚C and 5 min to 40%wt C at 300˚C and 60 min) at the expense of the char fraction. The energy quality of the bio-crude recovered resembled the bio-ethanol fuel, and it is far lower than the energy density found in commercial gasoline. This has to do with the oxygen content remaining in bio-crude oil that, lower than the feedstock, is much higher compared to commercial gasoline. Therefore, downstream upgrading processes are necessary to convert the obtained bio-crudes into drop-in fuels. Moreover, HTL products were characterized using novel FTIR techniques coupled with multivariate statistics, GCMS, and HPLC offering a deeper understanding on the mechanisms behind hydrothermal processing of waste