In situ photodecyanation of steel industry wastewater in a pilot scale.

The photodegradation of cyanide from steel industry wastewater was explored in pilot plant scale using hydrogen peroxide (HO) under UV irradiation. However, it was interesting to notice that only HO or only UV was inefficient to degrade the cyanide from industrial wastewater. There was a synergy between HO and UV radiation for the degradation of cyanide. The generated hydroxyl radicals from irradiated HO were responsible for the efficient degradation of cyanide. Besides, the dissolved oxygen had a significant role on the degradation process. The photodecyanation rate was faster initially and decreased gradually thereafter ensuring the industrial viability of the process. The dozing rate of HO and the UV lamp power were systematically optimized and they were found to be 8 l/m and 640 W, respectively. The photodecyanation kinetics was also explored simultaneously and the rate constant was found to be 3.21 × 10 min at the selected dosage of 8 l/m. This work demonstrates a scalable and facile decyanation technique from steel plant effluent without generation of toxic by-products.