Treatment of tannery wastewater using aluminium formate: influence of the formate over sulphate based coagulant

Tannery industries provoke the conspicuous quantity of deleterious effluent which has to be treated prior to discharge into the environment. Pre-treatment of tannery wastewater with aluminium sulphate is well known over decades, but due to the corrosive nature of sulphate this pre-treated water causes several issues in the biological treatment system. To overcome this issue a study was performed to understand the coagulant activity of aluminium formate and aluminium sulphate. The effect of coagulant activity as a function of pH and coagulant dose of Aluminium formate was studied and found that it surpassed aluminium sulphate in terms of Cr(VI), sulphate and COD removal by 10%, 6% and 10% respectively, while turbidity removal for both coagulants was found approximately equal. Possible mechanistic approach to the coagulation property of aluminium formate and aluminium sulphate could be inter particle bridging and sweep coagulation respectively. Formate [HCOO-] can be utilized as a counter anion in the place of commonly used sulphate anions as it is biodegradable, non-toxic and corrosive free compound. Therefore, Aluminium formate can be a promising coagulant for the pre-treatment of tannery wastewater.