Optimization of chloride removal from tannery soaking wastewater by lime alum process

Abstract

Chloride removal from tannery-soaking wastewater has been a significant issue due to the presence of high levels of chloride in the wastewater produced by the tanning industry. High levels of chloride ions are harmful to human health as well as the environment if the water is not properly treated. Traditional methods like ion exchange, reverse osmosis, demineralization, coagulation, electrodialysis, precipitation, and adsorption are costly and often ineffective. The lime-alum process offers a promising alternative. This method involves adding lime and alum to the wastewater, forming hydroxide and aluminum hydroxide flocs that precipitate and remove chloride ions. Our research identified the optimal conditions for this process: a pH of 10, reaction time of 25 minutes, temperature of 25°C, and alum dosage of 0.5 grams. Under these conditions, chloride removal reached 635 mg/L. The lime-alum process is cost-effective, using inexpensive chemicals and low energy, and it can be easily integrated into existing wastewater treatment systems. These findings highlight its potential as an efficient solution for chloride removal in the tanning industry.