Design of a biorefinery for bioethylene production and lignin recovery from forest industrial waste

CARDOZO, ROCÍO E.; FELISSIA, FERNANDO E.; AREA, M. CRISTINA; CLAUSER, NICOLÁS M.; VALLEJOS, MARÍA E.

Congreso; CIADICYP; 2022

Pine sawdust is a lignocellulosic waste from the primary processing of wood, highly available inArgentina. It could be a promising raw material to produce second-generation (2G) ethanol and itsderivatives, like bioethylene-based products. 2G bioethanol production requires sawdust fractionationto achieve high cellulose yields. Lignin, a relevant source of aromatic organic compounds to obtainhigh-valued and carbon-neutral lignin-based products, is generated as a byproduct. Currently, only alow percentage (2%) of the generated lignin, principally in pulp manufacturing processes, is destinedfor other applications such as biomaterials; the remainder goes to combustion processes for energygeneration. This work assesses two potential scenarios for pine sawdust valorization in a biorefineryframe. Organosolv pretreatments were applied to obtain bioethylene, lignin, fermentable sugars, andenergy production.The raw material was pine sawdust from a local industrial sawmill (Misiones, Argentina). Two casesof organosolv pulping were studied: (I) alkaline pulping with NaOH and ethanol recovery, and (II)autocatalyzed pulping only with ethanol recovery. Figure 1 shows the pulping conditions. Mass andenergy balances, yields, lignin availability as a byproduct, and economic parameters (investment,production cost, others) were compared and analyzed.Delignification is 25% higher per ton of dry sawdust in Case I, whereas 88 kg and 111 kg of bioethyleneper ton of dry sawdust are obtained in Cases I and II, respectively. The energy consumption for Case Iis almost three times higher than in Case II. Bioethylene production plus lignin and sugars recovery arepromising alternatives for this low-cost raw material in Argentina. Techno-economic evaluationallowed the feasibility of both cases at different scales of comparison