Behavior of fast and slow phosphorus release from sewage sludge–derived biochar amended with CaO

• Published in: Environmental science and pollution research international 2021-06, Vol.28 (22), p.28319-28328
• Main Authors: Liu, Qiang, Li, Jiayi, Fang, Zheng, Liu, Yangyang, Xu, Yunfeng, Ruan, Xiuxiu, Zhang, Xiaolei, Cao, Weimin
• Format: Article
• Language: English
• Subjects: Apatite; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Bioavailability; Charcoal; Chlorides; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fertilizers; Ionic strength; Orthophosphate; Phosphorus; Pyrolysis; Releasing; Research Article; Sewage sludge; Soils; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-021-12725-z

The pyrolyzation of sewage sludge (SS) could efficiently transform inherent phosphorus (P) into bioavailable phosphate forms, which endows SS-derived biochar (SSB) the potential as a soil fertilizer. However, the details about the release behavior of P in SSB have not been systematically investigated. This study evaluated the fast and slow P releasing behaviors from SSB and CaO-amended SSB prepared under different pyrolysis temperature. The higher pyrolysis temperature and CaO addition could enhance the conversion of non-apatite inorganic phosphorus (NAIP) into more bioavailable apatite inorganic phosphorous (AP). Acidic and alkaline conditions were favorable for the fast release of P from SSB. Higher ionic strength condition gave greater releasing amounts of TP and the SO 4 2- facilitating a rapid release of TP than those for Cl - and NO 3 - . SSBs with CaO addition showed a much slower TP release than those without CaO both in fast release (24 h, with CaO: 0.05~0.4 mg TP g -1 SSB, e.g., without CaO 0.5~5 mg TP g -1 SSB) and slow release tests (21 days, with CaO: 1.2~4.1 mg TP g -1 SSB, e.g., without CaO 1.8~5.7 mg TP g -1 SSB). Ortho-P release was more remarkable for the SSB amended with CaO (~54% of TP), which was likely due to the formation of orthophosphate. The results of this study suggested that SSB prepared by high pyrolysis temperature and CaO addition had high potential as a slow P-releasing fertilizer for the soil.