Evaluation of heavy metals stability and phosphate mobility in the remediation of sediment by calcium nitrate

Jizhi Zhou, Mingqi Zhang, Meiting Ji, Zhenghua Wang, Hao Hou, Jia Zhang, Xin Huang*, Andrew Hursthouse, Guangren Qian

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
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Abstract

The injection of oxidants is one of the useful remediation technology for eliminating hydrogen sulfide (H2S) and ammonia (NH3/NH4+) in aquatic sediments. In the current work, the impact of calcium nitrate injection on the release of heavy metals associated with phosphate was evaluated in a column test of sediment with overlying water at a volume ratio of 1: 1 for 131 days. Sulfide was significantly oxidized by calcium nitrate, as its amount was reduced substantially by 85% from the 20th to the 30th day, with a decrease in the oxidation-reduction potential to -68 mV and a simultaneous increase in pH to 9.83. Over 50% of the mobile Zn, Pb and Cu were reprecipitated in the sediment when the phosphate was partially released. It is proposed that the heavy metal immobilization was related to the phosphate content in the pore water due to the precipitation of heavy metals and phosphorus on the surface of Fe hydroxide particles after oxidation. This is supported by chemical fraction analysis of the heavy metals in the sediment, which indicated increased residual fractions of heavy metals. Our results provide an insight into the remediation of sediment by oxidation with a self-stabilization of heavy metals and phosphate.
Original languageEnglish
Pages (from-to)1017-1026
Number of pages10
JournalWater Environment Research
Volume92
Issue number7
Early online date23 Jan 2020
DOIs
Publication statusPublished - 31 Jul 2020

Keywords

  • heavy metal
  • nitrate calcium
  • iron oxyhydroxide
  • phosphorus
  • redox immobilization
  • sediment

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