Performance of a Wet-type Nonthermal Plasma Reactor for NOx, SOx, and Wastewater Treatment

The removal of nitrogen oxides (NOx) and sulfur oxide (SOx) is conducted using a wet-type plasma reactor without chemical agent. In the reactor, NO is firstly oxidized to NO2 by air plasma, and then NO2 and SO2 are absorbed into a water film on the inner wall of the reactor. The wastewater absorbing NO2 and SO2 must be treated before drain. In particular, nitrogen compound such as nitrate ion $(\mathbf{NO}_{\mathbf{3}}^{-})$ and nitrite ion $(\mathbf{NO}_{\mathbf{2}}^{-})$ are harmful. Therefore, the wastewater is treated by argon (Ar) plasma to remove $\mathbf{NO}_{\mathbf{3}}^{-}$ and $\mathbf{NO}_{\mathbf{2}}^{-}$. As a result, more than 98% of NO and SO2 were removed in the air plasma. Furthermore, it is demonstrated that $\mathrm{NO}_{3}^{-}$ and $\mathbf{NO}_{\mathbf{2}}^{-}$ in the wastewater were decreased by Ar plasma. From these results, it is confirmed that this wet-type discharge plasma reactor is useful for the simultaneous removal of NOx and SOx.