Comparison of the EE/O values (Table 5) shows that the UVC
irradiation process cannot be considered cost effective since the
EE/O value exceeds the recommended value of 10 kWh/kL for an
economically favourable process [10]. Addition of hydrogen peroxide
to the irradiation system greatly enhanced the efficiency since
it required less time (15–30 min) to achieve the targeted colour
reduction. When treatment was stopped at this stage, biodegradable
products were generated and could be removed in subsequent
biological treatment, improving the overall process efficiency and
performance.