Exploring the Selective Lactic Acid Production from Food Waste in Uncontrolled pH Mixed Culture Fermentations Using Different Reactor Configurations
Carboxylic acid production from food waste by mixed culture fermentation is an important future waste management option. Obstacles for its implementation are the need of pH control and a broad fermentation product spectrum leading to increased product separation costs. To overcome these obstacles, the selective production of lactic acid (LA) from model food waste by uncontrolled pH fermentation was tested using different reactor configurations. Batch experiments, semi-continuously fed reactors and a percolation system reached LA concentrations of 32, 16, and 15 gCODLA/L, respectively, with selectivities of 93%, 84%, and 75% on COD base, respectively. The semi-continuous reactor was dominated by Lactobacillales. Our techno-economic analysis suggests that LA production from food waste can be economically feasible, with LA recovery and low yields remaining as major obstacles. To solve both problems, we successfully applied in situ product extraction using activated carbon.
KeywordsLactic acid Mixed culture fermentation Food waste Percolation system Microbial community Biorefinery
The author would like to acknowledge the financial support from Masdar Institute (Project 2BIONRG, 12KAMA4, and BIOREF, 13KAMA1), to help fulfill the vision of the late President Sheikh Zayed Bin Sultan Al Nahyan for sustainable development and empowerment of the United Arab Emirates and humankind.
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