117 | Fascicule 3 ANNALS of Faculty Engineering Hunedoara – International Journal of Engineering Tome XIV [2016] – Fascicule 3 [August] ISSN: 1584-2665 [print; online] ISSN: 1584-2673 [CD-Rom; online] a free-access multidisciplinary publication of the Faculty of Engineering Hunedoara 1. Alberto COZ, 1. Tamara LLANO, 1. Cristina RUEDA, 1. Natalia QUIJORNA, 2. Edmond MAICAN HYDROLYSIS AND SEPARATION OF LIGNOCELLULOSIC BIOMASS IN A SULPHITE PROCESS TO VALORISE THE MAIN FRACTIONS WITHIN THE BIOREFINERY CONCEPT 1. Universidad de Cantabria, Green Engineering and Resources Research Group, SPAIN 2. Politehnica University of Bucharest, Faculty of Biotechnical Systems Engineering, ROMANIA ABSTRACT: Physico-chemical and biological processes can be used to transform different pulp and paper industries through integrated forest biorefineries in order to valorise all of the main fractions of the lignocellulosic biomass (cellulose, hemicellulose and lignin). In this work, hydrolysis and fractionation processes have been studied in a sulphite pulp mill to obtain not only dissolving pulp from the cellulose but also lignosulphonates from the lignin and fermentation products from the hemicellulose. Delignification and hydrolysis experiments have been carried out at laboratory scale in order to increase the valorisation opportunities and trying to decrease the inhibitors in the final by-product. In addition, detoxification or separation treatments have been developed in order to separate the lignosulphonates and other inhibitors from the sugar substrate. Keywords: biorefinery, sulphite pulping, hydrolysis, lignosulphonates, sugars, detoxification 1. INTRODUCTION Biorefinery is the sustainable processing of biomass into a spectrum of marketable products (food, feed, materials, and chemicals) and energy (fuels, power, heat) via biochemical, thermo-chemical, chemical or mechanical processes [14]. In this sense, lignocellulosic biomass, consisting of three major fractions: cellulose (35-50% dry weight), hemicelluloses (20-35%) and lignin (10-25%) [4], shows a high interest in biorefinery and several related industries as pulp and paper mills can be transformed into forest biorefineries [11]. Among the pulping processes, the acid sulphite process is based on the extraction of cellulose by the attack under acidic conditions (pH of 1.35 ± 0.15) in the presence of excess free SO2 [14]. The main advantages of this process are (i) the production of a high-purity cellulose (dissolving pulp) for not only textile fibre production but also for high value-added films, plastics and coatings among others [14], and (ii) the possibility to obtain a high separation of all of the main components, cellulose, hemicellulose and lignin [7]. In addition, lignosulphonates are formed during the process, showing several applications as plasticizers and additives in construction. During the first step of the process, due to the heterogeneous nature of the lignocellulosic biomass, in addition to sugars, other decomposition products can be obtained and they can act as inhibitors in the fermentation process. Therefore, detoxification processes should be added to the process to valorize all of the fractions and to decrease the quantity of inhibitors [4]. In this work, a sulphite pulp mill is studied in order to be transformed into a forest biorefinery. Delignification, hydrolysis and detoxification processes have been developed in order to separate the three main fractions: lignosulphonates from the lignin, dissolving pulp from the cellulose and sugars from the hemicellulose.