Removal of Residual COD in Biologically Treated Paper-Mill Effluent and Degradation of Lignin Using Nonthermal Plasma Unit

Abstract

This manuscript focused on the degradation behavior of lignin and the reduction of residual COD in the biologically treated paper-mill effluent by means of ionized gas from nonthermal plasma unit. The removal efficiencies of COD, lignin, and color after treated with ionized gas were over 95, 93, and 97%, respectively. It has been found that the degradation of aromatic ring has been proved by FTIR, ¹H NMR and UV spectra. The degradation of lignin through ionized gas was accompanied with the increase of and the decrease in pH. The results show that the residual COD in the biologically treated paper-mill effluent contains NBD matter with aromatic ring compounds. Also NBD organic matter such as aromatic ring in effluent treated with ionized gas was degraded. The residual COD declined by 60% at the ionized gas flow rate 5 L/min and HRT 30 min.

Keywords:

• Lignin
• Paper-mill wastewater
• Nonthermal plasma
• Ionized gas
• Residual COD
• NBD matter
• Aromatic ring
• Degradation