Perspective for Emission and Control of Nitrous Gas in Biological Wastewater Treatment

Abstract

Being the third most significant anthropogenic greenhouse gas, nitrous gas (N2O) has 300-fold stronger effect than carbon dioxide (CO2) and 4 ~ 30-fold stronger effect than methane (CH4). In this study, the main sources and mechanisms of N2O emission from biological wastewater treatment were reviewed, and the possible mitigation strategies were discussed. Parameters including dissolved oxygen, temperature, pH, organic carbon, and nitrite concentration have influences on the emission of N2O. The possible mitigation strategies were put forward by controlling these parameters in biological wastewater treatment and inducing modified technologies such as simultaneous nitrification-denitrification, denitrifying phosphorus removal, and aerobic granular sludge. In order to obtain a near-zero N2O emission, applying typical catalysts in the nitrification or denitrification tank to decompose N2O into harmless gas is recommended. Moreover, a method of developing photochemical processes to transform N2O could also be suggested.

Assessing the Impact of Urban Form on the Greenhouse Gas Emissions from Household Vehicles: A Review

“…The associated effects on the environment include noise and air pollution, land occupancy, and traffic accidents. Urban dispersion uses up land that would otherwise be available for ecological uses, while the excessive energy consumption leads to air pollution, exhaustion of non-renewable energy, and gas emissions, which ultimately contribute to climate change (Anderson et al, 1996;Wu and Xia, 2019;Chen et al, 2020;Liu et al, 2020). Ewing and Rong (2008) conducted a study investigating the relationship between the choice of housing type and urban form, and found that multifamily housing is seven time less popular in dispersed areas than in compact areas.…”