Non-thermal plasma review : assessment and improvement of feasibility as a retrofitted technology in tertiary wastewater purification

Abstract

Chlorination, ozonation and non-thermal plasma water purification technologies were compared in terms of their effectiveness, efficiency, capital and operating costs, energy yield and chemical demand. Retrofitting plasma technology to chlorination plants offered the lowest capital cost (ZAR 14,000 or USD 253,376 based on the current South African Reserve Bank rate of ZAR/USD of 18.0983) and the most effective contaminant removal (of the three possible combinations). However, this combination yielded the highest operating costs (ZAR 586,000 per annum or USD 10.6 million) and the lowest energy efficiency. It was concluded that retrofitting chlorination plants with plasma technology is feasible. However, plasma generators should be redesigned to consume less energy or to operate using renewable energy. Furthermore, research should be performed on contaminants of emerging concern to establish a deadline after which their concentration must not exceed a specified limit. This will accelerate the implementation of plasma technology and secure the health of our posterity.