Exploring GHG emissions in the mainstream SCEPPHAR configuration wastewater resource

The wastewater sector paradigm is shifting from wastewater treatment to resource recovery. In addition, concerns re-garding sustainability during the operation have increased. In this sense, many water utilities have become aware of the potential GHG emissions during the operation of wastewater treatment. This study assesses the nitrous oxide and methane emissions during the long-term operation of a novel wastewater resource recovery facility (WRRF) con-figuration: the mainstream SCEPPHAR. The long-term N2O and CH4 emission factors calculated were in the low range of the literature, 1 % and 0.1 %, respectively, even with high nitrite accumulation in the case of N2O. The dynamics and possible sources of production of these emissions are discussed. Finally, different aeration strategies were implemented to study the impact on the N2O emissions in the nitrifying reactor. Results showed that operating the pilot-plant under different dissolved oxygen concentrations (between 1 and 3 g O2m-3) did not have an effect on the N2O emission fac-tor. Intermittent aeration was the aeration strategy that most mitigated the N2O emissions in the nitrifying reactor, obtaining a reduction of 40 % compared to the normal operation of the pilot plant.

Automated summary

The wastewater sector is shifting towards resource recovery and there is increasing concern for sustainability during operation. This study assesses the emissions of nitrous oxide and methane during the long-term operation of a novel wastewater resource recovery facility and discusses their dynamics and possible sources. The results show that intermittent aeration is the most effective strategy to mitigate nitrous oxide emissions.