Valorization of Negative-Cost Industrial Waste at the Forest Biorefinery

林业部门占全国GDP的12%（580亿加元），是全国直接雇用23.5万加拿大人的主要雇主。然而，由于海上竞争激烈，石油价格不稳定，石油储量不确定，对全球变暖的担忧，以及绿色燃料和化学品的全球运动和激励措施，加拿大林业部门需要使其产品和市场多样化，以创造额外的收入并保持竞争力。这可以通过将加拿大的纸浆和造纸米尔斯厂发展成森林生物精炼厂来实现-森林生物精炼厂是一种加工和转化设施，充分整合森林生物质和生物质废物，同时生产市场产品，包括纸浆和纸张、化学品和能源。该NSERC发现补助金的目标是通过从加拿大纸浆和造纸米尔斯厂提供的负成本生物质废物（初级和二级污泥）中创造新价值，为森林生物精炼厂的发展做出贡献。污泥填埋和焚烧由于其过高的处理成本和潜在的环境危害性而在经济和环境上不具有吸引力。该提案旨在通过将污泥废物转化为可发酵的糖、乳酸和聚乳酸（PLA）来实现污泥废物的价值。乳酸广泛用于食品工业和作为PLA的原料，而PLA是一种可生物降解的聚合物，可以在各种工业应用中取代合成塑料。建议首先将造纸污泥酶促分解为简单的可发酵糖，然后使用稳健且高产的发酵生物体将这些糖生物转化为乳酸，所述发酵生物体将另外工程化以获得最佳性能。将在分批、补料分批、重复和半连续培养中评价不同的发酵方法以生产乳酸。在优化条件下生产乳酸后，将设计一种新的催化工艺，该工艺允许在没有事先进行乳酸纯化的情况下生产PLA。成功实施该研究计划的预期效益包括：1）技术效益：将纸浆和造纸米尔斯产生的废物流转化为具有经济意义的增值产品的技术; 2）经济效益：降低生产成本，降低能源投入和化学品消耗; 3）环境效益：减少废物产生，废物利用，减少温室气体排放; 4）社会和教育福利：培训高素质的科学家和工程师劳动力，他们将为加拿大未来的社会经济增长和繁荣发挥他们的技能;制造业创造新就业机会的潜力很大;以专利、出版物、报告和演示文稿的形式创造新知识。

The Forest Sector contributes 12% to the national GDP (CAD 58 billion) and is a major employer directly employing 235,000 Canadians across the country. However, due to the strong offshore competition, unstable oil prices and uncertainties about oil reserves, concerns about global warming, and global movement and incentives for green fuels and chemicals, the Canadian Forest Sector needs to diversify its products and markets, in order to create additional revenues and remain competitive. This can be accomplished by evolving the Canadian pulp and paper mills into Forest Biorefineries - processing and conversion facilities that fully integrate forest biomass and biomass waste for the simultaneous production of marketplace products, including pulp and paper, chemicals and energy. This NSERC Discovery grant has the objective to contribute to the development of the Forest Biorefinery by creating new value from the negative-cost biomass waste (primary and secondary sludge) that is available at Canadian pulp and paper mills. The sludge landfilling and incinerating is not economically and environmentally attractive due to the prohibitively high treatment costs and potential environmental harmfulness. This proposal aims at valorization of the sludge waste by converting it to fermentable sugars, lactic acid and polylactic acid (PLA). Lactic acid is widely used in the food industry and as a raw material for PLA, whereas PLA is a biodegradable polymer that can replace synthetic plastics in a variety of industrial applications. It is proposed to enzymatically decompose paper sludge to simple fermentable sugars first, followed by bioconversion of these sugars to lactic acid using a robust and highly-productive fermentation organism that will be additionally engineered for optimal performance. Different fermentation methods will be evaluated in batch, fed-batch, repeated and semi-continuous cultures for production of lactic acid. Following lactic acid production under optimized conditions, a new catalytic process will be designed that allows for PLA production without prior lactic acid purification. Expected benefits from the successful execution of this research program include: 1) Technical Benefits: Technology for conversion of waste streams generated at pulp and paper mills into value-added products of economic significance; 2) Economic Benefits: Reduced production costs, lower energy input and chemical consumption; 3) Environmental Benefits: Reduced waste generation, waste utilization, reduced greenhouse gas emissions; 4) Social and Education Benefits: Training of highly qualified workforce of scientists and engineers that will implement their skillsets for Canada’s future socio-economic growth and prosperity; high potential for new job creation in the manufacturing industry; new knowledge creation in the form of patents, publications, reports and presentations.