Control of internal phosphorus loading in eutrophic lakes using lanthanum-modified zeolite

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2017-11, Vol.327, p.505-513
• Main Authors: Wang, Zhe, Lu, Shaoyong, Wu, Deyi, Chen, Fangxin
• Format: Article
• Language: English
• Subjects: Eutrophication; Fractionation; Lanthanum; Phosphorus; Sediment; Zeolite
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2017.06.111

[Display omitted] •Lanthanum modified zeolite (LMZ) was prepared from coal fly ash.•LMZ greatly reduced P levels in water overlying sediment within 212day period.•Release of P from sediment under high pH or anoxic conditions was impeded by LMZ.•Releasable P species in sediment was converted to stable species by adding LMZ.•LMZ was shown to be a promising material to control internal P loading in lakes. Tackling the release of phosphorus (P) from sediments remains a challenge to mitigating the eutrophication of lakes. The current study investigated the efficacy of lanthanum-modified zeolite (LMZ), which was developed from coal fly ash via a one-pot process, to reduce P levels in a simulated water–sediment system. LMZ was dosed to bind releasable P fractions (i.e., labile P, reductant-soluble P, NaOH-P, and organic P fractions) in sediment of shallow lakes. LMZ treatment was found to be effective at decreasing the P concentration in water overlying sediment. On average, total P and soluble-reactive P were reduced by 81.1% and 86.9% in a 28-day sediment core incubation experiment and by 57.1% and 72.8% in a 212-day mesocosm experiment, respectively. LMZ decreased P release from sediment under high pH value (∼10.0) and anoxic conditions by 45.8% and 87.4% for total P and by 52.9% and 94.0% for soluble-reactive P, respectively. Adding LMZ induced a change of P in sediment from releasable P fractions to refractory P forms. Although aquatic parameters interfered with P binding, increasing the LMZ dosage enhanced the effect of LMZ. The control of internal phosphorus loading by LMZ was explained as follows: (i) capture of P from water; (ii) inhibition of P release from sediment; (iii) enhancement of P retention capacity of sediment; and (iv) inactivation of sediment P via the formation of stable P forms.