Simultaneous elimination of black-odor and stabilization of heavy metals in contaminated sediment using calcium peroxide/hydroxyapatite: Microbial responses and ecotoxicological effects

In this study, laboratory-scale experiments were conducted to investigate the feasibility of the combined use of calcium peroxide and hydroxyapatite (CaO2/HAP) for simultaneous black-odor sediment remediation and heavy metal stabilization. The ecotoxicological effects of remediated sediment were also evaluated based on biological toxicity. Results showed that CaO2/HAP effectively eliminated the black-odor and simultaneously stabilized heavy metals in the sediment. Under the optimal dosage ratio of CaO2/HAP (1:2), the acid volatile sulfides decreased to approximately 20 mg/kg (dry weight, dw) and oxidation-reduction potential increased from - 165 mV to approximately - 90 mV. The leaching of heavy metals meets the strictest standards (Level I) of the Technical Specification for Output Disposal of Contaminated Sediment Treatment Plant of River and Lake (SZDB/Z 236-2017). The indigenous microbial community succession occurred (p < 0.01), Proteobacteria and Firmicutes accounting for 75.54% and 20.19%, respectively, were the predominant bacteria in the remediated sediment. Additionally, CaO2/HAP remediated sediments were safer and more environmentally friendly than raw sediments, and were not biotoxic to the benthic environment (p < 0.01). This study provides new insights into the combined use of the beneficial amendments remediating heavy metal-contaminated black-odor river sediment.

Automated summary

In this study, the combined use of calcium peroxide and hydroxyapatite (CaO2/HAP) was investigated for simultaneous remediation of black-odor sediment and stabilization of heavy metals. The results showed that CaO2/HAP effectively removed the black-odor and stabilized heavy metals in the sediment. The leaching of heavy metals met strict standards and the remediated sediment was found to be safer and more environmentally friendly than raw sediment.