Influence of organic matter in wetland substrate on vanadium removal: A batch and column study

• Published in: Journal of water process engineering Vol. 68; p. 106359
• Main Authors: Hudson, A., Murnane, J.G., O'Dwyer, T., Courtney, R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2024
• Subjects: Alkaline wastewater; Constructed wetland; Alkaline wastewater; Constructed wetland
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2024.106359

Long term Vanadium (V) releases from alkaline wastewaters and associated risks to aquatic environments has highlighted the need to further develop the potential of passive treatment systems, including constructed wetlands (CWs). However, understanding the role and composition of CW substrate, including organic matter content, for V removal is limited. This work used batch and column studies to measure V removal and retention by adsorption in mixed compost and soil substrates, at both alkaline and neutral pH's (11 and 6). Batch studies carried out on (i) unamended topsoil, (ii) topsoil with 10 % compost, and (iii) topsoil with 20 % compost, showed that maximum V uptake was highest in the 20 % compost mix (1.47 mg/g) compared to unamended soil (0.76 mg/g) after 24 h contact time. A column leaching study using the 20 % compost to topsoil soil mix was batch loaded twice weekly with 50 mL of 100 mg V/ L at pH 6 and pH 11. After 18-weeks, the columns had retained 97 % and 87 % V for the pH 6 and pH 11 solutions respectively. Highest accumulated V was in the top 0–5 cm for the pH 6 (44.8 mg) and top 5-10 cm for pH 11 (56.4 mg) columns, reducing significantly with depth. Soluble V accounted for 46 % of the total in the pH 11 treatment, and 39 % in the pH 6 treatment. Results of this applied study imply a potential means of improving V retention in CW substrate by compost inclusion. Further investigations are needed to assess performance containing multiple trace elements. •Effective removal of V by biochar material may not be technically feasible at large scale.•Simulating constructed wetland treatment, V removal from wastewaters were assessed using unamended and organic amended soil.•Batch adsorption isotherm demonstrated higher V uptake in soils influenced by organic content.•Column leaching of V solutions at different pH (pH 6; pH 11) demonstrated higher V leaching at pH 11.•Sequential extraction of soil from columns showed soluble V was higher in 0–5 cm compared to 10-20 cm.