Nitrous oxide emissions of a mesh separated single stage deammonification reactor

Abstract

It is widely accepted that partial nitrification by ANAMMOX has the potential to become one of the key processes in wastewater treatment. However, large greenhouse gas emissions have been panobserved in many cases. A novel mesh separated reactor, developed to allow continuous operation of deammonification at smaller scale without external biomass selection, was compared to a conventional single-chamber deammonification sequencing batch reactor (SBR), where both were equally-sized pilot-scale reactors. The mesh reactor consisted of an aerated and an anoxic zone separated by a mesh. The resulting differences in the structure of the microbial community were detected by next-generation sequencing. When both systems were operated in a sequencing batch mode, both systems had comparable nitrous oxide emission factors in the range of 4% to 5% of the influent nitrogen load. A significant decrease was observed after switching from sequencing batch mode to continuous operation.

Operational experience

“…Inadequate control of these parameters can result in deterioration of nitrogen removal and foaming events • There may be additional operating costs for antifoaming agents and de-scalers, although these may be minimized by good operating practice around the dewatering device • Melanoidins have a high affinity for chelating nutrients which may influence the efficacy of supplement addition to enhance or maintain performance • Alkalinity/ammonia-N ratio may reduce over time, limiting the capacity of the plant for nitrogen removal. Addition of alkalinity may enhance performance • The risks of Legionnaires need to be considered • The influence of nitrous oxide emissions is significant when determining the environmental impact of the process (Schneider et al, 2011;Schoepp et al, 2018) Other than deammonification, which requires dilution of the digestate, it may be possible to use the COD within the digestate as a carbon source for denitrification (Bungay, 2018). At United Utilities' Leigh thermal hydrolysis plant, an Amtreat ® plant is installed.…”

Successful year-round mainstream partial nitritation anammox: Assessment of effluent quality, performance and N2O emissions

“…After carbon depletion, N removal by PNA can be performed in a single combined PNA stage or in a two-stage process (i.e., partial nitritation followed by anammox). In recent years, there has been significant debate regarding the preference of one- versus two-stage systems (one stage: ( Han et al., 2018 ; Li et al., 2016 ; Pérez et al., 2014 ; Schoepp et al., 2018 ; Vlaeminck et al., 2009 ); two-stage: ( Jung et al., 2021 ; Kouba et al., 2017 ; Kowalski et al., 2019 ; Poot et al., 2016 )). Single stage PNA results in lower peak nitrite concentrations because nitrite is, continuously or intermittently, reduced by anammox bacteria (AMX).…”