Pulsed corona discharge for degradation of aqueous humic substances

The research into oxidation of aqueous humic substances (HS) with pulsed corona discharge (PCD) was undertaken to estimate the energy efficiency of the treatment. The PCD system consists of a voltage pulse generator and reactor, in which the gas-phase discharge generating OH radicals and ozone treats the water showered between electrodes. The influence of HS initial concentration, pulse repetition frequency, water flow rate, and the atmosphere composition was evaluated by the decrease in total organic carbon (TOC) and color. The PCD treatment reduced TOC by 40 to 50% and the color by up to 97%. The PCD energy efficiency ranged about 20 g kW⁻¹ h⁻¹ in air and 30 g kW⁻¹ h⁻¹ in oxygen for the lowest initial color of about 50 Pt-Co degrees. Ozone contributed about 30% to the color reduction and only 15% to the reduction in TOC, indicating predominant role of OH radicals in mineralization of oxidation by-products.