modeling greenhouse gas emissions in a full-scale activated sludge unit based on benchmark simulation model – a case study of isfahan wastewater treatment plant

Background: the objective of this study was to establish a facility-level modeling tool to assess the performance of internal operational strategies and external emissions.methods: the biological process model in benchmark simulation model no. 2 (bsm2) was upgraded to include two-stage and four-stage nitrification, as well as denitrification processes, to effectively simulate nitrous oxide (n2o) production. emissions of carbon dioxide (co2), methane (ch4), and n2o were also incorporated, taking into account digestion, cogeneration, and sludge storage processes. the refined model was utilized in a case study at the isfahan wastewater treatment plant (wwtp) in iran to assess various operational strategies and explore potential challenges related to emission management.results: the simulation results, based on the model’s structural assumptions, indicate a negative impact on greenhouse gas (ghg) emissions associated with regional energy upgrades in the ventilation system and activated sludge sector. for example, variations in the biogenic and non-biogenic co2​ proportions were observed when the total suspended solids (tss) removal efficiency was altered, decreasing or increasing to 30/70 and 20/80, respectively. while off-site co2​ emissions can be mitigated, this reduction is offset by a significant rise in n2​o emissions. this is particularly concerning given that n2​o exhibits a greenhouse effect nearly 300 times greater than that of co2​.conclusion: it should be pointed out that numerous studies are needed to evaluate plant-wide control strategies in wwtps for informed and effective decision-making regarding performance optimization.