Sulphur compounds removal from an industrial landfill leachate by catalytic oxidation and chemical precipitation: From a hazardous effluent to a value-added product

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Barbosa Segundo, IDB (Author) Other; Silva, TFCV (Author) Other; Moreira, FC (Author) Other; Silva, GV (Author) Other; Boaventura, RAR (Author) Other; Vitor Vilar (Author) FEUP

Journal

Title: Science of the Total Environment

Vol. 655

Pages: 1249-1260

ISSN: 0048-9697

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 16 Citations

Associated Projects

AIProcMat@N2020 - Advanced Industrial Processes and Materials for a Sustainable North Region of Portugal2020

Other information

Authenticus ID: P-00P-Y39

DOI: 10.1016/j.scitotenv.2018.11.274

Abstract (EN): This study focused on the removal of sulphur compounds from a high-strength leachate of a hazardous industrial waste landfill. Firstly, sulphides (0.5 g L-1) and sulphites (2.5 g L-1) were catalytic oxidised at natural pH (8.7). Air or H2O2 were applied as oxidants and metals present in the leachate were used as catalysts. Distinct air flow rates and H2O2: sulphur molar ratios were tested. Concentrations of sulphide and sulphite lower than 1.0mg L-1 (emission limit value - ELV) were obtained after 5-h oxygenation or 1-min peroxidation under the best conditions, i.e. air flow rate of 1 L-air L-leachate(-1) min(-1) and H2O2: sulphur stoichiometric ratio. Aeration was considered unsafe since >33 volatile organic compounds (VOCs) and hydrogen sulphide (H2S) were released to the atmosphere. Thus, only the H2O2-oxidised leachate pursued treatment. Sulphates (13 g L-1) were removed by chemical precipitation as ettringite or barite applying different reactants contents and pH values. Without pH correction, sulphate contents below 2.0 g L-1 (ELV) were achieved using a [Ca-+(2)]:[Al3+]:[SO42-] molar ratio of 12:4:3 (2-fold stoichiometry) and a [Ba2+]:[SO42-] molar ratio of 1.0: 1.0 (1-fold stoichiometry). The analysis of precipitates by X-ray diffraction (XRD) showed a three-phase ettringite (only 67% corresponding to ettringite itself) and single-phase barite. Barite precipitation proved to be more appealing since a value-added product was obtained and, furthermore, less reactants were required. After sulphur compounds removal using H2O2-driven catalytic oxidation and chemical precipitation through barite, the leachate was suitable for biological treatment, despite the high salinity, and a high fraction of the organic load (46%) could be biologically oxidised.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12