Polylactic acid polymer (PLA) produced from renewable resources can be recycled at the end of life to constituent monomer, optically pure lactic acid (LA), by a combination of chemical and biological processes. Efficient application of this closed loop of LA-PLA plastics-LA can minimize accumulation of plastics waste that pollute land and oceans. Temperature-dependent hydrolysis of PLA in water to LA follows apparent first order decay kinetics after a short lag. A modified Gompertz equation can explain the overall hydrolysis process. Alkali increased the rate of hydrolysis of PLA and reduced the length of lag period compared to water alone. The stoichiometry of base added to LA released was 1.0. The highest lactic acid yield was 0.95 g g⁻¹ of PLA. d-LA in the syrup obtained after hydrolysis of PLA-plastics was removed using an engineered Escherichia coli to produce a l-LA syrup with an optical purity ≥ 99%. These results show that thermochemical hydrolysis of PLA-based plastics to LA with optimum amount of base followed by bio-based purification to l-LA is an effective method of recycling PLA-plastics for reuse.

由可再生资源生产的聚乳酸聚合物（PLA）可以在生命周期结束时通过化学和生物过程相结合的方式，回收为光学纯乳酸（LA）的组成单体。LA-PLA塑料-LA闭环的有效应用可以最大程度地减少污染土地和海洋的塑料废物的积累。短暂滞后后，温度依赖性的PLA在水中水解为LA遵循明显的一级衰减动力学。修正的Gompertz方程可以解释整个水解过程。与单独使用水相比，碱提高了PLA的水解速率并缩短了延迟期。添加到LA中的碱的化学计量为1.0。乳酸的最高产率为PLA的0.95gg ^-1。d使用工程化的大肠杆菌除去在PLA塑料水解后获得的糖浆中的-LA，以生产光学纯度≥99％的1 -LA糖浆。这些结果表明，用最适量的碱将PLA基塑料热化学水解为LA，然后将其生物基纯化为1 -LA是回收PLA塑料以再利用的有效方法。