Towards sustainability of lactic acid and poly-lactic acid polymers production

Lactic acid (LA) is a platform chemical which can be produced biotechnologically on agricultural residues, wastes and by-products and further used for production of biodegradable, biocompatible LA polymers. These polymers are mostly used for high-end applications but they have potential for much wider application with decrease in production costs. Available technologies and strategies are reviewed in order to point out the issues, challenges and solutions relevant to increase sustainability and competitiveness of LA production on agricultural residues and wastes. Data on chemical composition, regional and seasonal availability of agricultural residues, wastes and by-products are lacking to provide predictable and effective combining for LA production. Precision agriculture, remote sensing and integration with data on chemical composition can help in better planning and more adequate exploitation of available sources in future. Novel pretreatments for the most abundant lignocellulosic feedstocks, which allow utilization of carbohydrates in LA production and side streams like lignin in other biorefineries are needed. Integration of pretreatment, hydrolysis and fermentation under non-sterile conditions or open fermentation mode should enable easier scale up and decrease energy consumption and costs without sacrificing LA purity. Capital investments in improvement of the available technologies are high. Support from policy makers stimulating production of LA polymers from second and third generation feedstocks will help in research, development and faster adoption on larger scale. For production of LA polymers with tailored properties, it is essential to choose the most productive method for LA production and separation from these complex substrates. The shift in research interest from LA polymerization towards green processing of LA polymers products is occurring and that will be the additional driving force for the field in future.