Juan Francisco Morales Arteaga (Author), Anela Kaurin (Author), Domen Leštan (Author)

Abstract

Sewage sludge (SS) is a potential resource for P and other nutrients, but often contaminated with metals. SS containing Pb-102, Zn-968, Cu-267, Cr-101, Mn-222, and Fe-8374 mg kg$^{-1}$ was washed in a batch process for 1 h with a recycled washing solution containing 50 mmol L$^{-1}$ of recycled EDTA and 50 mmol L$^{-1}$ H2SO4, solid/liquid ratio 1/7 (w/V). After solid/liquid separation, the washed SS was further rinsed 3-times with cleansed recycled solutions. EDTA and process solutions were recycled/cleansed in a pH gradient of 12.5–2.0 imposed by addition of CaO and H2SO4 (the ReSoil® method). EDTA, recycled as ineffective Ca-EDTA, was activated by capturing Ca with H2SO4. The process was closed-looped, no wastewater was generated, solid waste was centrifuged away. 10 consecutive SS washing batches preserved the quality of the process solutions. Metals were mainly removed from the SS organic fraction, the average removal was Pb-35, Zn-59, Cu-60, Cr-19, Mn-25, and Fe-1%. Washing reduced the leachability of Cu and Cr from SS by 13.4 and 3.5 times, but increased the leachability of Pb, Zn, Mn, and Fe by 2.5, 3.8, 1.9, and 1.6 times, respectively. Metal concentrations in the leachates were below the limits stipulated as hazardous. The content of accessible P and K in washed SS decreased by 24 and 45%, and the total N decreased by 10%. Overall, the results prove the feasibility of the novel SS washing process.

Keywords

potential toxic elements;sewage sludge;toxic metals;soil washing;chelating agents;contaminated soil;EDTA;toxic emissions;phosphorus;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL BF - Biotechnical Faculty
UDC: 502.1
COBISS: 122208003 Link will open in a new window
ISSN: 0045-6535
Views: 27
Downloads: 19
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Other data

Secondary language: Slovenian
Secondary keywords: toksične kovine;potencialno škodljivi elementi;EDTA;pranje tal;onesnaženost tal;remediacija tal;
Type (COBISS): Article
Pages: 9 str.
Volume: ǂVol. ǂ307
Issue: ǂpt. ǂ 2, 135917
Chronology: 2022
DOI: 10.1016/j.chemosphere.2022.135917
ID: 16525535