Synthesis of Layered Double Hydroxides with Fermentation Liquid of Organic Waste to Extract Short-Chain Fatty Acids as a Biodenitrification Carbon Source

Short-chain fatty acids (SCFAs) were extracted from artificial and actual anaerobic fermentation liquid of organic waste via the synthesis of layered double hydroxides (LDHs), which was then used as external carbon source in biodenitrification process. Results of X-ray diffraction and Fourier transform infrared analysis indicate that SCFAs were successfully intercalated into LDHs in both artificial system and actual anaerobic fermentation liquid of food waste, with good slow release performance. When using SCFAs-LDH and SCFAs-Na as carbon source with COD/N ratio of 4:1, the nitrate removal efficiency and the utilization efficiency of carbon source were improved from 42.3% and 30.3% to 81.3% and 58.1%, respectively. A dynamic "release-utilization" balance of carbon source was always kept during denitrification process when using SCFAs-LDH, so that higher removal efficiency of nitrate and utilization efficiency of carbon source were obtained simultaneously. This study could help to recover SCFAs from organic wastes efficiently as a denitrification carbon source with slow release performance.