After being collected from the wastewater treatment system, duckweed biomass which is rich in starch and protein has the potential to be converted to valuable chemicals. This study aimed to establish a fermentation process for bioconversion of duckweed biomass derived from wastewater treatment to lactic acid (LA) by Lactobacillus casei. The Lactobacillus casei CICC 23184 showed the best LA production ability in duckweed-based medium among five strains. Simultaneous saccharification and fermentation (SSF) and separated hydrolysis and fermentation (SHF) were conducted, and the SSF had better performance even with lower enzyme dosage. No extra nitrogen source needed supplying into duckweed-based media. In batch fermentation, biomass loading of 220 g kg⁻¹ was optimal with LA concentration of 72.51 ± 2.81 g kg⁻¹ and yield of 0.35 ± 0.01 g g⁻¹_{dry biomass}. The highest LA concentration (100.36 ± 3.31 g kg⁻¹), yield (0.38 ± 0.01 g g⁻¹_{dry biomass}), and productivity (2.09 ± 0.07 g kg⁻¹ h⁻¹) were obtained through fed-batch SSF at a final biomass loading of 260 g kg⁻¹. This study demonstrated that it is feasible to utilize duckweed biomass as feedstock to produce LA through fermentation, and a fed-batch SSF at high-biomass loading was successfully established. This study provides a novel strategy for sustainable recycling of duckweed biomass derived from wastewater treatment.

从废水处理系统中收集后，富含淀粉和蛋白质的浮萍生物质可能会转化为有价值的化学物质。这项研究旨在建立一种发酵工艺，用于将干酪处理的废水处理产生的浮萍生物质转化为乳酸（LA）。该干酪乳杆菌CICC 23184显示，浮萍基于介质五株名列前茅LA生产能力。同时进行了糖化和发酵（SSF）和分离的水解和发酵（SHF），即使在较低的酶用量下，SSF也具有更好的性能。无需向浮萍基培养基中供应额外的氮源。在分批发酵中，生物量负荷为220 g kg ^-1最佳的LA浓度为72.51±2.81 g kg ^-1，产量为0.35±0.01 g g ^-1_干生物量。最终通过补料分批SSF获得最高的LA浓度（100.36±3.31 g kg ^-1），产量（0.38±0.01 g g ^-1_干生物质）和生产率（2.09±0.07 g kg ^-1  h ^-1） 260 g kg ^-1的生物量负荷。这项研究表明，以浮萍生物质为原料通过发酵生产LA是可行的，并成功建立了高生物量的补料分批SSF。这项研究为废水处理产生的浮萍生物量的可持续利用提供了一种新的策略。