A critical review on treatment of saline wastewater with emphasis on electrochemical based approaches

Journal
Process safety and environmental protection  
Volume
158
Start Page
625
End Page
643
Citation
Process Safety and Environmental Protection 158: 625-643 (2022-02)
Publisher DOI
10.1016/j.psep.2021.11.054
Scopus ID
2-s2.0-85121648002
Publisher
Elsevier
Peer Reviewed
true
Increasing discharge of saline wastewater (SWW) from different industries and environmental risks associated with it has compelled researchers to search for efficient treatment methods and safe disposal techniques. Unfortunately, several industries such as agro-food, oil & gas, tannery, and pulp & paper require brine solution units to obtain a finished product that further elevates the salinity of discharged wastewater to a magnitude of 1-3% by weight of NaCl. Among the conventional treatment procedures, electrochemical technologies proved to be more efficient, robust and cost-effective. Electrocoagulation (EC), an electrochemical based technology that produces in situ coagulant which ultimately assist in pollutant removal. It is even more suitable for the treatment of saline water as salinity increases conductivity which further enhances the EC process efficiency. However, the elevated anodic dissolution may increase the cost which can be reduced by using scrap metals as sacrificial electrodes out of iron and aluminum. The mechanism of salt removal from SWW using EC is similar to other pollutant removal mechanisms as salt species being coagulated by the metal hydroxides and are further removed as sludge. However, optimization of process parameters in EC is essential to maintain a balance between anodic passivation and higher metal dissolution so as to make the process efficient. This review paper highlights the theory of the EC technology, process parameters, potential application and recent developments of EC for the treatment of various types of SWW as well as economical assessment associated with this technology. Most of the recent research concerning EC for SWW treatment has been concentrated on the pollutant-specific evaluation without paying special attention to the process optimization, process modelling and commercial usage. This review further outlines the challenges with the recommendations for encouraging research options that can potentially enhance the EC performance, lower the operational costs and expand its range of applications for SWW treatment.
DDC Class
540: Chemie
600: Technik
620: Ingenieurwissenschaften
More Funding Information
This review article recevied no funding.