Feasibility of Glow Discharge Nonthermal Plasma as an Alternative Pretreatment for Low-Carbon Wastewater in a Biological Nutrient Removal Plant

Biological treatment is insufficient for infield treatment of domestic wastewater that contains low amounts of carbon. This study proposes a pretreatment process for enhancing the nutrient removal efficiency by improving the biodegradability of organic matter using glow discharge nonthermal plasma (GDNTP), which generates several strongly oxidizing active species. A series of batch experiments was conducted at pH 5.0 and 9.0 to investigate removal of nitrogen based on either physiochemical effects or improvement of the biodegradability of organic matters by the GDNTP pretreatment. At pH 5.0, total nitrogen (TN) was not removed by chemical reactions with active species from the GDNTP generator, whereas more TN was removed by chemical reactions or air stripping with the gas discharged from GDNTP at pH 9.0. Part of nitrogen removal was not achieved by ammonia air stripping, but by the improvement of biodegradation due to the GDNTP pretreatment for each operational sequencing batch reactor cycle. Findings indicate that GDNTP pretreatment improves the denitrifying of nitrate rather than producing a better carbon/nitrogen (C/N) ratio.