This book discusses the environmental impact of wastewater produced from leather processing tanneries. It discusses the conventional technologies used to treat this effluent wastewater. Electro-chemical oxidation is an advanced treatment process which was employed in the current work. A novel rotating disc electro-chemical reactor was designed to treat the tannery wastewater. The reactor was successful in removing over 98% of the total organic carbon (TOC) present in the wastewater.