TY - JOUR
T1 - Reclamation of available phosphorus and separation of heavy metals from sewage sludge via FeCl3-assisted electrokinetic treatment and pyrolysis
AU - Wang, Xutong
AU - Li, Huwei
AU - Wang, Junxia
AU - Buss, Wolfram
AU - Bogush, Anna
AU - Mašek, Ondřej
AU - Zhang , Youjun
AU - Yu, Fan
AU - Yan, Beibei
AU - Cheng, Zhanjun
AU - Cui, Xiaoqiang
AU - Chen, Guanyi
AU - Ignatyev, Konstantin
N1 - Publisher Copyright:
© 2025 Elsevier Ltd
PY - 2025/7
Y1 - 2025/7
N2 - Recycling of sewage sludge and the endogenous phosphorus (P) is a promising strategy for sustainable development, while the disposal of heavy metals (HMs) in sewage sludge and the recovery of targeted P species remain challenges. An innovative method coupling electrokinetic treatment with pyrolysis was proposed in the present study to achieve the effective reclamation of available P and the separation of HMs from sewage sludge. The pristine and FeCl3-assisted electrokinetic treatment were employed for the removal of HMs from sewage sludge and to modify the P species, and the subsequent pyrolysis (300–700 °C) was conducted for the recovery of available P along with the production of biochar. The X-ray absorption near-edge spectroscopy (XANES), 31P liquid nuclear magnetic resonance (NMR) spectroscopy, and sequential chemical extraction were used to systematically determine the evolution of P during the combined treatment of sewage sludge. 19.69–24.80 % of Ni, Cu, and Zn were removed from sewage sludge after pristine electrokinetic treatment, and the HM removal efficiency was further elevated to 47.01–56.86 % with the assistance of FeCl3. Consequently, in comparison with the raw sewage sludge-derived biochars (SBs), the biochars derived from FeCl3-assisted electrokinetic treated sewage sludge (FESBs) contained much lower HM contents and showed higher stability of HMs. The FeCl3-assisted electrokinetic treatment converted alkaline biochars dominated by poorly soluble Ca-phosphates into neutral to slightly acidic biochars dominated by Al/Fe-associated phosphates. This transformation greatly improved the available P concentrations determined by diffusive gradients in thin film in FESBs by 0.6–1.3 folds compared to untreated SBs. Therefore, coupling FeCl3–assisted electrokinetic treatment with pyrolysis could be a promising strategy to achieve the reclamation of available P and the separation of HMs from sewage sludge.
AB - Recycling of sewage sludge and the endogenous phosphorus (P) is a promising strategy for sustainable development, while the disposal of heavy metals (HMs) in sewage sludge and the recovery of targeted P species remain challenges. An innovative method coupling electrokinetic treatment with pyrolysis was proposed in the present study to achieve the effective reclamation of available P and the separation of HMs from sewage sludge. The pristine and FeCl3-assisted electrokinetic treatment were employed for the removal of HMs from sewage sludge and to modify the P species, and the subsequent pyrolysis (300–700 °C) was conducted for the recovery of available P along with the production of biochar. The X-ray absorption near-edge spectroscopy (XANES), 31P liquid nuclear magnetic resonance (NMR) spectroscopy, and sequential chemical extraction were used to systematically determine the evolution of P during the combined treatment of sewage sludge. 19.69–24.80 % of Ni, Cu, and Zn were removed from sewage sludge after pristine electrokinetic treatment, and the HM removal efficiency was further elevated to 47.01–56.86 % with the assistance of FeCl3. Consequently, in comparison with the raw sewage sludge-derived biochars (SBs), the biochars derived from FeCl3-assisted electrokinetic treated sewage sludge (FESBs) contained much lower HM contents and showed higher stability of HMs. The FeCl3-assisted electrokinetic treatment converted alkaline biochars dominated by poorly soluble Ca-phosphates into neutral to slightly acidic biochars dominated by Al/Fe-associated phosphates. This transformation greatly improved the available P concentrations determined by diffusive gradients in thin film in FESBs by 0.6–1.3 folds compared to untreated SBs. Therefore, coupling FeCl3–assisted electrokinetic treatment with pyrolysis could be a promising strategy to achieve the reclamation of available P and the separation of HMs from sewage sludge.
KW - Electrokinetic treatment
KW - Heavy metal
KW - Phosphorus
KW - Pyrolysis
KW - Sewage sludge
UR - https://www.scopus.com/pages/publications/105005829943
U2 - 10.1016/j.jenvman.2025.125882
DO - 10.1016/j.jenvman.2025.125882
M3 - Article
SN - 0301-4797
VL - 387
JO - Journal of Environmental Management
JF - Journal of Environmental Management
M1 - 125882
ER -