Nuclear chemistry

Phenol

Calcination

Catalysis

Engineering

Sewage treatment

Pyrolysis

Geotechnical engineering

Sewage sludge

Pollutant

Telecommunications

Computer science

Nitrogen

Dewatering

Waste management

Biochar

Organic chemistry

Degradation (telecommunications)

Environmental chemistry

Chemistry

Mineralization (soil science)

Pulp and paper industry

Chemical Engineering Journal

Conversion of waste sludge into biochar-based catalysts has been considered as a feasible alternative for sludge treatment, and dewatering of waste sludge is a key process for further treatment and disposal. In this study, KMnO4 was used as both a chemical conditioner to assist Fe-rich sludge dewatering and a chemical modifier to incorporate Mn oxides into the biochar catalysts. Results showed that the sludge dewatering was substantially improved when KMnO4 dosage was above 13% DS (dry sludge), and more than 99% of Mn was retained in the sludge cake. After pyrolysis of the sludge cake, a series of Mn,Fe-codoped biochar catalysts (assigned to x-Mn-FeBC) were obtained. The catalysts could activate peroxymonosulfate (PMS) well for complete removal of phenolic contaminants including phenol, bisphenol A (BPA) and 2,4-dichlorophenol (DCP) over a wide pH range (2.5–12) with the co-existence of water constituents. After 5 consecutive cycles, the catalytic performance of 13%-Mn-FeBC was decreased by half, but it could be fully recovered by simple calcination at 600 oC. It was proposed that radical and non-radical oxidation processes worked together for organic degradation, but non-radical pathways involving 1O2 oxidation and electron transfer between PMS and organic played more crucial roles. This study proposed a novel sludge treatment process by combining enhanced sludge dewatering with efficient catalyst preparation, and the as-prepared catalysts were promising in PMS activation and organic degradation.

Coupling of KMnO4-assisted sludge dewatering and pyrolysis to prepare Mn,Fe-codoped biochar catalysts for peroxymonosulfate-induced elimination of phenolic pollutants