abstract
Although the scientific community recognises the issue of iron wastage as ferric sludge following Fenton processes, there has been limited focus on valorising of this sludge. This work proposes a circular solution to valorise Fenton sludge as catalyst of the Fenton process in the treatment of industrial wastewater. To achieve this, sludges were collected after treating pulp bleaching wastewater with Fenton processes catalysed either by iron sulphate (homogeneous Fenton) or residual iron dust (heterogeneous Fenton). These sludges were then pyrolyzed for 30 min at 600 degrees C. Subsequently, raw wastewater was treated using four different catalysts: two untreated sludges and two pyrolyzed sludges from both Fenton processes. All materials achieved similar AOX removal ranging 50 - 58 % within 30 min. Untreated sludges maintained consistent catalytic activity over three consecutive treatment cycles without regeneration, while the AOX removal with pyrolyzed sludges decreased to approximately 30 % after three cycles. However, pyrolyzed sludges released up to 90 % less iron into the wastewater, reducing secondary pollution and suggesting a longer lifespan. Most AOX removal was due to oxidation, primarily driven by center dot OH, with less than 10 % attributable to adsorption onto the catalyst surface.
keywords
WASTE-WATER TREATMENT; PAPER-INDUSTRY; ELECTRO-FENTON; HETEROGENEOUS FENTON; LANDFILL LEACHATE; IRON-OXIDES; PULP; OXIDATION; REUSE; HYDROGEN
subject category
Chemistry; Engineering
authors
Ribeiro, JP; Marques, CC; Neves, MC; Gomes, HGMF; Sarinho, L; Tarelho, LAC; Nunes, MI
our authors
Helena Gomes
Junior Researcher
João Peres Ribeiro
Junior Researcher
Luana Sarinho
PhD Student
Márcia Carvalho Neves
Junior ResearcherGroups
G3 - Electrochemical Materials, Interfaces and Coatings
G4 - Renewable Materials and Circular Economy
G5 - Biomimetic, Biological and Living Materials
Projects
Collaboratory for Emerging Technologies, CoLab (EMERGING TECHNOLOGIES)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
Thanks are due to FCT/MCTES for the financial support to CESAM (UIDP/50017/2020 + UIDB/50017/2020 + LA/P/0094/2020) and CICECO - Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020) . This work was developed in the scope of INOVC + (CENTRO-01-0246-FEDER-000044) , co-funded by Centro2020, Portugal2020 and the ERDF. J.P. Ribeiro, C.C. Marques, and H.G.M.F. Gomes acknowledge FCT for their PhD Grants SFRH/BD/141133/2018, 2021.08959.BD, and 2020.09864.BD, respectively. M.C. Neves acknowledges FCT for the research contract CEECIND/00383/2017/CP1459/CT0031 (DOI 10.54499/CEECIND/00383/2017/CP1459/CT0031) under the Scientific Employment Stimulus-Individual Call.