20.500.12556/RUL-140919 Removal of toxic metals from sewage sludge by EDTA in a closed-loop washing process 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$^{-1}$ H$_2$SO$_4$, 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 H$_2$SO$_4$ (the ReSoil® method). EDTA, recycled as ineffective Ca-EDTA, was activated by capturing Ca with H$_2$SO$_4$. 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. potential toxic elements toxic metals soil washing chelating agents contaminated soil EDTA toxic emissions phosphorus sewage sludge toksične kovine potencialno škodljivi elementi EDTA pranje tal onesnaženost tal remediacija tal true false true Angleški jezik Slovenski jezik Članek v reviji 2022-09-21 09:02:34 2022-09-21 09:02:36 2022-10-13 08:21:31 0000-00-00 00:00:00 2022 0 0 9 str. pt. 2, art. 135917 Vol. 307 2022 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 502.1 0045-6535 10.1016/j.chemosphere.2022.135917 122208003 1-s2.0-S0045653522024109-main.pdf 1-s2.0-S0045653522024109-main.pdf 1 6BDEB2F2CB1B454EA9B651B84C064336 358fb2d2265c581ef5d3793707f1358f432940928157f741f81a20cde499cca8 ff372d7e-397b-11ed-92af-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=161767 https://www.sciencedirect.com/science/article/pii/S0045653522024109 1 4aec2882-397b-11ed-92af-00155dcfd717 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=161766 Biotehniška fakulteta 0 0 0