Milk to milk bottles: Sustainable polymer grade lactic acid from residual dairy lactose

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Society is pressuring industry and government to reduce, recycle, and reuse waste and are demanding that new and existing technologies are environmental, sustainable, and biosourced. The objective of this project is to convert lactose to lactic acid that will serve as a feedstock for a biopolymer (polylactic acid): milk to milk bottles. Revenues from the dairy industry approached 15 billion$ in Canada but it it produces a waste stream of lactose water (0.05 g/g) in water together protein, lipids, and minerals. Quebec alone produces 75000 tonnes of non-fat milk solids and permeates (waste) per year that is either disposed of or exported. In the next 4 years, international treaties will restrict shipments of this waste outside national borders. To export/dispose of the milk solids (65 % lactose) will incur a cost approaching 1 $/kg, which is prohibitively expensive. Converting this stream to a value-added product will contribute to the economic health of the dairy industry that is under pressure. The high lactose loading makes it an attractive bio-feedstock to produce fuels, specialty chemicals, and monomers. Biofuels (methane, ethanol via fermentation) and syngas are options but the economic incentive is low and the capital and operating costs are too high without financial support from government. Rather than breaking down lactose to simple molecules, this projects seeks to maintain as much of the functionality of the compound as possible and will target lactic acid. Acid catalysts hydrolyze and hydroxylate lactose (and other sugars). This project will explore several catalysts and spinning disk reactor technology to produce concentrated stream lactic acid, which is an emerging platform chemical building-block in the food, cosmetics, chemicals, and pharmaceutical industries. Examples include acrylic acid (2300 $/t) and bulk biochemicals. The market of lactic acid is forecast to increase annually by over 11 % and is expected to reach $13 billion in sales by 2025. The price of lactic acid starts at 1700 $/t and the biopolymer polylactic acid sells for more than 3000 $/t. Although fermentation of lactose to lactic acid is already practiced commercially, productivity is low and capital investment is high. We anticipate order of magnitude savings (shut down economics) by applying a spinning disk reactor that will increase reaction rates and thereby reduce capital. This recalcitrant reaction requires high heat and mass transfer rates to contact the lactose and catalyst. Mass transfer between fluid and catalyst in the conventional fluidized bed, fixed beds, slurries, and trickle bed reactors depend essentially on the velocity, which is on the order of 1 m/s - several orders of magnitude lower than what is possible with the spinning disks. Other gas-liquid, liquid-liquid, and gas-liquid-liquid systems, practiced in the Canadian chemical and energy industries, are other possible applications.