Inactivation of phosphorus in the sediment of the Lake Taihu by lanthanum modified zeolite using laboratory studies

• Published in: Environmental pollution (1987) Vol. 247; pp. 9 - 17
• Main Authors: Li, Xiaodi, Xie, Qiang, Chen, Shouhui, Xing, Mingchao, Guan, Tong, Wu, Deyi
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2019
• Subjects: Eutrophication; Lake; Phosphorus; Release; Sediment; Phosphorus; Sediment; Lake; Release; Eutrophication
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2019.01.008

Release of phosphorus (P) from sediment to overlying water has to be dealt with to address algal blooms in eutrophic lakes. In this study, the sediment from the Lake Taihu was amended with lanthanum modified zeolite (LMZ) to reduce P release under different pH, temperature and anaerobic conditions. LMZ performed well, to decreasing P concentration in Lake Taihu water in the presence of sediment. The EPC0 value, the critical P concentration at which there was neither P adsorption nor P release, was lowered by adding LMZ, suggesting that amendment with LMZ could diminish the risk of P release from the sediment. From the Langmuir isotherm model, the adsorption capacity of phosphate by LMZ was estimated to be 64.1 mgP/g. The LMZ-amended sediment had a higher content of stable P forms (HCl-P and Res-P) and a lower content of P forms with a high (NH4Cl-P and BD-P) or medium-high (NaOH-P and Org-P) risk of release, when compared with the original sediment. The fractionation simulates conditions which release potentially mobile P which can then be simply re-bound to LMZ. At high pH (>9.0), anaerobic condition or high temperature promoted the liberation of P from sediment. However, P release could be greatly inhibited by LMZ. In addition, although Mn2+ and NH4+ ions were released from sediment under the anaerobic condition, the release could also be hindered by adding LMZ. LMZ is a promising P inactivation agent to manage eutrophication in the sediment of Lake Taihu. [Display omitted] •High P retention capacity of lanthanum modified zeolite (LMZ) was verified.•LMZ decreased P level in water equilibrated with sediment of the Lake Taihu.•Adding LMZ converted releasable P forms to stable P forms in sediment.•LMZ diminished P release from sediment under high pH, low ORP or high temperature.•Negative charges on LMZ contributed to the retention of released NH4+ and Mn2+. Lanthanum modified zeolite effectively diminished the release of P from sediment under high pH, anaerobic condition or high temperature, showing excellent ability to inactivate P in sediment.