Nutrient removal and emission of nitrous oxide and methane by a sequencing batch reactor treating wastewater with and without landfill leachate

Abstract

Wastewater and landfill leachate treatment processes have the potential to generate nitrous oxide (N2O) and methane (CH4), both significant greenhouse gases (GHG). However, little is known about these emissions when a combined treatment approach (wastewater with leachate) is utilized. This study aimed to assess the emissions of these gases and nutrient removal in an anaerobic/aerobic/anoxic sequencing batch reactor (SBR) employed for treating wastewater with landfill leachate (1% v/v). Leachate contributes significantly to the removal of organic matter and nutrients, primarily phosphorus. The production and emission of N2O occurred during the aerobic phase, whereas CH4 was produced in the anaerobic and anoxic phases. This gas was emitted at the beginning of the aerobic phase and in the end of anoxic phase. The emission factors obtained in this work were 0.0108 and 0.0119 kg N2O-N per kg TNinfluent and 0.000225 and 0.000253 kg CH4-C per kg CODinfluent with and without landfill leachate, respectively. Regarding CO2-equivalent, the N2O was the major contributor, accounting for 99% of the emitted GHG by the process. Further studies are required; however, the main findings of this study suggest that this system may be appropriate when lower GHG emissions are required.