Experimental and statistical modeling of the effect of process modification and wastewater characterization on greenhouse gas emissions for a dairy industry wastewater treatment plant: a minimization approach

This study aimed to determine the effect of design conditions and wastewater characterization on greenhouse gas (GHG) emissions from an industrial wastewater treatment plant. Analysis of variance, correlation analyses, heat-mapping, and principal component analyses (PCA) were performed to determine the correspondence between GHG emissions and wastewater characterization. Then, a new empirical model based on the correlation of wastewater characterization has been developed. This study has concentrated on using process modification to mitigate GHG emissions in terms of the European Green Deal. If an aeration tank is operated at 36 h of hydraulic retention time and 20 days of solid retention time at design conditions, an average reduction of 45.4, 45.3, and 45.2% in carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) emissions, respectively, have been ensured. According to correlation analysis, a moderately significant positive correlation was found between effluent chemical oxygen demand values and CO2 and CH4 values (r = 0.909, r = 0.937). N2O emissions were closely related to Total Kjeldahl Nitrogen input values (r = 0.876). From this point of view, GHG emissions have been calculated using this correlation, and the results overlapped with the monitoring values. The estimated results of GHG emissions based on wastewater characterization have converged to in situ monitoring results, by an average of 82%.