Identification of Key Basic Parameters Involved in Carbon Emissions in Full-Scale Wastewater Treatment Plants

Abstract

In this study, carbon emissions in three full-scale wastewater treatment plants were determined by the emission factor method. Moreover, the correlation between basic parameters (influent water parameters and pollutant removal efficiency) and carbon emissions was examined via a structural equation model (SEM). The results showed a significant variation in the total carbon emission intensity of plants over time. The average total carbon emission intensity of plants A, B and C were 0.314, 0.404 and 0.363 kg eqCO2/m³, respectively. Meanwhile, the indirect carbon emission caused by energy and chemical agent consumption accounts for the majority of total carbon emissions (about 85%). Generally, statistical analysis results show that carbon emission intensity is positively correlated with pollutant removal efficiency. Notably, RTN showed the highest positive correlation with Eind, followed by RTN > RCODCr > RTP > TN > RNH3-N > NH3-N > TP. Moreover, capacity showed the greatest negative contribution to Eind, followed by CODCr. In contrast, the positive contribution to Edir was followed by the sequence of RTN > RCODCr > TN > RNH3-N > NH3-N. Notably, CODCr showed a significantly negative correlation with Edir, while TP and its removal showed little correlation with Edir.