1 Department of Environmental Engineering, School of Environment, University of Tehran, P. O. Box 14155-6135, Tehran, Iran.
2 Department of Environmental Engineering, School of Environment, University of Tehran, P. O. Box 14155-6135, Tehran, Iran; Department of Building, Civil and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada. Electronic address: yusef.mehdizadeh@mail.concordia.ca.

Estuaries play a crucial role in preventing the influx of metals from rivers into seas, thereby offering potential insights for the water purification industry. This study seeks to identify the key parameters (including pH, electricity conductivity (EC), and Eh) influencing the removal efficiency of Mn, Zn, Cu, Co, and Ni during natural and electro-flocculation processes in the Siahroud River estuary. The experiments were conducted in three stages, each representing varying salinity levels and voltage conditions, to determine the most effective parameters for metal removal. The findings revealed that heavy metal flocculation rates were highest at lower salinities (0.5 to 1.5 PSU), with no significant improvement in contaminant removal observed with increasing voltage. Electro-flocculation efficiency was found to be more dependent on Eh. Overall, the flocculation processes reduced the annual total dissolved metal content from 14.84 to 6.46 tons, underscoring the potential of this method in water quality management.