Triclocarban transformation and removal in sludge conditioning using chalcopyrite-triggered percarbonate treatment.

ABSTRACT

Herein, a facile combination approach of chalcopyrite and sodium percarbonate (CuFeS2+ SPC) was established to augment both TCC removal efficiency and sludge dewatering. Results showed that utilizing the CuFeS2 dosage of 600 mg/g total solids (TS) under the optimal condition, along with the SPC dosage of 12.5 mg/g TS, an initial pH of 4.0, and a reaction duration of 40 min, led to a substantial reduction of 53.9% in the TCC content within the sludge, accompanied by a notable decrease of 36.9% in the water content. Compared to well-studied iron-based advanced oxidation processes, CuFeS2 + SPC treatment proved to be more cost-effective and environmentally friendly. Mechanistic findings demonstrated that •OH oxidation played a significant role in TCC removal, with O2•- and 1O2 acting as secondary factors. During the CuFeS2 + SPC process, the received •OH, O2•-, and 1O2 destroyed the main binding sites of extracellular polymeric substances to TCC, including tryptophan-like protein, amide, CO stretch, and -COO- functional groups. As a result, approximately 50% of TCC was partially degraded within the solid sludge phase after the attack of radicals. Meanwhile, the decreased macromolecular organic compounds in solid sludge attenuated the binding efficacy of TCC, giving rise to the transfer of partial TCC to the liquid phase. Ultimately, the TCC in sludge was successfully removed, and five transformation products were identified. This study significantly contributes to our understanding regarding TCC transformation and removal in the sludge conditioning process.