Process Safety and Environmental Protection, Vol.147, 1066-1076, 2021
Accelerating phosphorus release from waste activated sludge by nitrilotriacetic acid addition during anaerobic fermentation process and struvite recovery
Phosphorus (P) recovery from waste activated sludge (WAS) could achieve sustainable development and reduce environmental hazards simultaneously. The objective of this study was to enhance P release from WAS by nitrilotriacetic acid (NTA) addition and struvite recovery. The maximal P release efficiency reached 90.3 % from WAS at the dose of 25.0 mM NTA after anaerobic fermentation 12 h. The NTA addition promoted nonapatite inorganic phosphorus (NAIP) and apatite phosphorus (AP) release from WAS while it had a negative effect on organic phosphorus (OP) release. The NTA was beneficial for the protein release from WAS, but it inhibited the release of NH4'-N. By means of struvite precipitation, the P043 --P and NH4'-N recovery rates at optimal initial pH = 9 of the fermentation supernatant reached 92.9 % and 51.5 %, respectively. Meanwhile, the purity and yield of the produced struvite were 85.8 % and 174.0 mg/g SS (per gram of dry sludge) determined by elemental analysis, respectively. The levels of heavy metals in struvite products were below the permissible limits of Cultivated Land Application Standard. Therefore, the results of this study enriched the P recovery path from WAS to guide the application. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.