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Potential of ash from agricultural waste as substitute of commercial FeCl3 in primary treatment of landfill leachate

Ghanbari Azad Pashaki, Saeed; Khojastehpour, Mehdi; Ebrahimi-Nik, Mohammadali; Tedesco, Silvia

Authors

Saeed Ghanbari Azad Pashaki

Mehdi Khojastehpour

Mohammadali Ebrahimi-Nik



Abstract

Due to the ever increasing global population, higher volumes of industrial waste discharges to landfill have caused major problems for the environment. This study investigated the performance of rice straw ash (RSA) as a natural coagulant under different conditions for the treatment of landfill leachates by coagulation-flocculation and microfiltration, with and without addition of FeCl3. The highest performing treatment conditions (RSA = 2.48 g/L, FeCl3 = 4.98 g/L, settling time = 54.75min) were achieved with the combined use of RSA and FeCl3 as coagulant and led to a sludge volume index of 41.65 mL/g, 51.27% COD removal and 76.48% total suspended solid removal. In contrast, FeCl3 alone achieved slightly better COD and total suspended solid removal rates, however it resulted in higher sludge volume index and sludge production. The combined use of RSA and FeCl3 reduced the consumption of these two coagulants by 78.76% and 46.69% respectively. Functional groups and thermal stability of the flocs showed that RSA + FeCl3 synergistically enhance the mechanisms of the coagulation-flocculation process, including adsorption by particle's bridging, charge neutralization and size of flocs. Combining the coagulants resulted in increased van der Waals forces and lower attractive forces of the inter-colloidal energy barrier in the leachate. Additionally, the highest and lowest heavy metals removal rates for treatment by microfiltration were found for Fe (92.15%) and Mg (7.63%), with a total heavy metals removal efficiency in the range of 6.08–90.78%. The findings of this study show that RSA can serve as a natural eco-friendly coagulant both alone and in combination with FeCl3 in the leachate treatment.

Citation

Ghanbari Azad Pashaki, S., Khojastehpour, M., Ebrahimi-Nik, M., & Tedesco, S. (2024). Potential of ash from agricultural waste as substitute of commercial FeCl3 in primary treatment of landfill leachate. Journal of Environmental Management, 351, Article 119932. https://doi.org/10.1016/j.jenvman.2023.119932

Journal Article Type Article
Acceptance Date Dec 23, 2023
Online Publication Date Dec 30, 2023
Publication Date 2024-02
Deposit Date Oct 2, 2024
Journal Journal of Environmental Management
Print ISSN 0301-4797
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 351
Article Number 119932
DOI https://doi.org/10.1016/j.jenvman.2023.119932