Valorization of Negative-Cost Industrial Waste at the Forest Biorefinery

林业部门占全国国内生产总值的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，由于近海竞争激烈，油价不稳定，石油储量不确定，对全球变暖的担忧，以及全球对绿色燃料和化学品的流动和激励，加拿大林业部门需要使其产品和市场多样化，以创造额外收入并保持竞争力。这可以通过将加拿大纸浆和造纸厂演变为森林生物精炼厂来实现--加工和转化设施完全整合森林生物质和生物质废物，用于同时生产包括纸浆和纸张、化学品和能源在内的市场产品。这笔NSERC发现基金的目的是通过利用加拿大纸浆和造纸厂可获得的负成本生物质废物(初级和次级污泥)创造新的价值，为森林生物炼油厂的发展做出贡献。由于高昂的处理成本和潜在的环境危害，污泥的填埋和焚烧在经济上和环境上都不具吸引力。这项建议旨在通过将污泥废物转化为可发酵的糖、乳酸和聚乳酸(PLA)来实现污泥的有价化。乳酸被广泛用于食品工业和作为聚乳酸的原料，而聚乳酸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。建议首先用酶法将造纸污泥分解成简单的可发酵糖，然后使用一种强大而高产的发酵生物体将这些糖生物转化为乳酸，该发酵生物体将被额外设计以实现最佳性能。不同的发酵方法将在分批、补料分批、重复和半连续培养中进行评估，以生产乳酸。在优化条件下生产乳酸之后，将设计一种新的催化工艺，允许在不进行乳酸提纯的情况下生产聚乳酸。成功实施这项研究计划的预期效益包括：1)技术效益：将纸浆和造纸厂产生的废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)社会和教育效益：培训高素质的科学家和工程师队伍，他们将为加拿大未来的社会经济增长和繁荣运用他们的技能；在制造业创造新的就业机会的潜力很大；通过专利、出版物、报告和演示的形式创造新知识。**

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. **