In-situ recycling strategy for co-treatment of antimony-rich sludge char and leachate: Pilot-scale application in an engineering case.

[Display omitted] • Sb-rich sludge char/leachate was co-treated via a novel in-situ recycling strategy. • LMCF characterisations and working mechanisms were scrutinized. • The performance of a pilot-scale pre-treatment system was evaluated. A novel in-situ recycling strategy is proposed for the co-disposal of antimony-rich dewatered sludge char (ADSC) and sludge leachate, and this strategy is further applied in a pilot-scale pre-treatment system. The preparation and operating conditions of lightweight micro-electrolysis ceramic fillers (LMCF) for ADSC were systematically studied, and LMCF characterisations and working mechanisms were scrutinised using SEM-mapping, XRD, XPS, EPR, BET, GF-AAS and CV examination. The results indicated that optimal preparation parameters for LMCF operation were 35% iron scrap content, a 1:2 vol ratio for Fe/ADSC, which was sintered at 900 ℃ for 2 h. Under the initial pH was 3.0 and the aerating intensity was 1 cm3·cm−2·s−1, the Sb-species were concentrated on the porous surface of the LMCF, degraded by various reactive oxygen species (ROS) released from Fe-C cells, and co-precipitated with FeOOH on the used LMCF surface. Thirty-one days of pilot-scale operations indicated that backwash was essential to maintain the LMCF with high efficiency regarding the total Sb removal and the biodegradability improvement of the actual sludge leachate. Lastly, preliminary economic assessment and suggestions for engineering-scale application were proposed. [ABSTRACT FROM AUTHOR]