TY - JOUR
T1 - Acidic hydrothermal carbonization of sewage sludge for enhanced alkaline extraction of phosphorus and reduced co-extraction of trace elements
AU - Tiwari, Satya Brat
AU - Veksha, Andrei
AU - Chan, Wei Ping
AU - Fei, Xunchang
AU - Liu, Wen
AU - Lisak, Grzegorz
AU - Lim, Teik Thye
N1 - Publisher Copyright:
© 2024
PY - 2025/1
Y1 - 2025/1
N2 - This study presents a two-stage process to recover phosphorus (P) from sewage sludge (SS) hydrochar, aimed at reducing trace element (TE) contamination. SS, mixed with Al-rich alum sludge (AS), underwent acidic HTC to convert Ca-P to Al-P. Alkaline extraction of hydrochar produced a P-rich, TE-deficient extract, as Al-P dissolves at high pH (> 12), leaving TEs insoluble. Optimal conditions for maximum P recovery were high temperature (∼240 °C), Al/P molar ratio (APMR) of ∼4, and feedstock pH of ∼3 – 4. This design process achieved 82 % alkaline P recovery, 34 % higher than the reference process. Overall P recovery ranged from 59 – 75 % in the design process, compared to 30 – 37 % in the reference process. Solid-state NMR revealed the Al-P association in hydrochar through surface complexation. TEs were mainly concentrated in the hydrochar. Thus, this method offers co-treatment of two waste streams with simultaneous resource recovery.
AB - This study presents a two-stage process to recover phosphorus (P) from sewage sludge (SS) hydrochar, aimed at reducing trace element (TE) contamination. SS, mixed with Al-rich alum sludge (AS), underwent acidic HTC to convert Ca-P to Al-P. Alkaline extraction of hydrochar produced a P-rich, TE-deficient extract, as Al-P dissolves at high pH (> 12), leaving TEs insoluble. Optimal conditions for maximum P recovery were high temperature (∼240 °C), Al/P molar ratio (APMR) of ∼4, and feedstock pH of ∼3 – 4. This design process achieved 82 % alkaline P recovery, 34 % higher than the reference process. Overall P recovery ranged from 59 – 75 % in the design process, compared to 30 – 37 % in the reference process. Solid-state NMR revealed the Al-P association in hydrochar through surface complexation. TEs were mainly concentrated in the hydrochar. Thus, this method offers co-treatment of two waste streams with simultaneous resource recovery.
KW - Biochar
KW - Heavy metal
KW - Hydrothermal treatment
KW - Phosphorus recovery
KW - Sequential extraction
KW - Solid-state NMR
UR - http://www.scopus.com/inward/record.url?scp=85205769503&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85205769503&partnerID=8YFLogxK
U2 - 10.1016/j.resconrec.2024.107936
DO - 10.1016/j.resconrec.2024.107936
M3 - Article
AN - SCOPUS:85205769503
SN - 0921-3449
VL - 212
JO - Resources, Conservation and Recycling
JF - Resources, Conservation and Recycling
M1 - 107936
ER -