The Performance of Ultrafiltration Process to Further Refine Lactic Acid from the Pre-Microfiltered Broth of Kitchen Waste Fermentation

Lactic acid (LA) is an important chemical material facing rapid demand in recent years. The oriented fermentation of kitchen waste is a promising route for economic LA production. However, the refinement of LA from fermentation broth is a spiny issue. In this study, the performance of ultrafiltration (UF) process for the refinement of LA from the pre-microfiltered broth of kitchen waste fermentation was first investigated. The results showed that with 50 KDa polyethersulfone membrane, under the optimum pressure of 120 KPa, the pH of 6.0, and the backflushing mode with the deionized water for 3 min, the best performance was achieved with the chroma removal efficiency, turbidity removal efficiency, protein removal efficiency and total sugar removal efficiency of 54.3%, 89.8%, 71.7% and 58.5%, respectively, and LA recovery efficiency was 93.6%. The results indicated that the UF process could further effectively refine the pre-microfiltered broth of kitchen waste fermentation, and the combination of microfiltration and UF process is ideal for achieving desirable LA refinement performance. This study verified the feasibility of UF process in LA refinement from pre-microfiltered broth of kitchen waste fermentation, and based on the results, the further exploration of proper post-process to treat UF filtrate for obtaining LA product with higher quality should be explored in the future.