Greenhouse Gases Emissions from Wastewater Treatment Plants: Minimization, Treatment, and Prevention

Abstract

The operation of wastewater treatment plants results in direct emissions, from the biological processes, of greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as indirect emissions resulting from energy generation. In this study, three possible ways to reduce these emissions are discussed and analyzed:(1)minimization through the change of operational conditions,(2)treatment of the gaseous streams, and(3)prevention by applying new configurations and processes to remove both organic matter and pollutants. In current WWTPs, to modify the operational conditions of existing units reveals itself as possibly the most economical way to decrease N2O and CO2emissions without deterioration of effluent quality. Nowadays the treatment of the gaseous streams containing the GHG seems to be a not suitable option due to the high capital costs of systems involved to capture and clean them. The change of WWTP configuration by using microalgae or partial nitritation-Anammox processes to remove ammonia from wastewater, instead of conventional nitrification-denitrification processes, can significantly reduce the GHG emissions and the energy consumed. However, the area required in the case of microalgae systems and the current lack of information about stability of partial nitritation-Anammox processes operating in the main stream of the WWTP are factors to be considered.

Correlation between Air Quality and Wastewater Pollution

“…Municipal wastewater treatment plants are known to be one of the minor sources of greenhouse gases that are distributed in the atmosphere. Generally, there are three major sources of greenhouse gases (methane, carbon dioxide, and nitrous oxide) which are easily and frequently emitted into space, they are also found to cause indirect emissions from energy generation process [23,24]. Aerobic biological treatment plants produce very large amounts of greenhouse gases as they require a large amount of energy to carry out various processes.…”

Environmental and Energy Assessment of Municipal Wastewater Treatment Plants in Italy and Romania: A Comparative Study

“…Carbon footprint Direct and indirect GHG emissions of two model WWTPs (with anaerobic digestion and simultaneous aerobic sludge stabilization) CO 2 emissions [13] Incorporation of carbon footprint and GHG quantification in MWWTP modelling GHG emissions [14] Evaluation of methane emissions from an MWWTP with sludge digestion Methane emissions [15] Minimizing N 2 O emissions and carbon footprint on a full-scale sequencing batch reactor N 2 O emissions, carbon footprint [16] GHG emissions from WWTPs: minimization, treatment, and prevention GHG emissions [6] Energy assessment…”

Realising the circular bioeconomy

“…For example, aerobic biological wastewater treatment produces GHGs while carrying out essential wastewater purification, and research is being directed to reducing these emissions (e.g. Campos et al, 2016). Current treatment of municipal wastewater accounts for approximately 3% of global electricity consumption and 5% of non-CO2 GHG emissions, principally methane from anaerobic digestion (Li et al, 2015).…”