Fate and emission of methyl mercaptan in a full-scale A2/O plant using TOXCHEM Simulation

Abstract

Methyl mercaptan (methanethiol) is one of the essential volatile, repugnant compounds released from wastewater treatment plants. This work uses a TOXCHEM simulator to model emission production and dispersal of odorous methyl mercaptan gas in full-scale A2/O plants. The sewage treatment plant (STP) in Karbala served as the basis for the case study, which showed that the two most significant processes in the system were emissions and degradation. Models were calibrated and validated to ensure that all data were within predefined limits. The root means square error (RMSE) and correlation coefficient (R) showed that the model was close to an ideal fit. 30.4% and 27.1% of all such gas were released into the atmosphere at 37°C in the summer and 12°C in the winter, respectively; 0.0096 and 0.45% were released with wastewater; 0.0.32 and 0.19% were absorbed by sludge; and 69.31% and 71.9% were degraded. To gain a better understanding of the production and dispersal of CH₄S emissions, a sensitivity analysis was also conducted. This was done by looking at the main influencing factors in the treatment process of the A2/O system, such as wind speed, wastewater temperature, flowrate and MLSS concentration in aeration reactors. Regarding the forecasting generation and dispersion of CH4S gas in an A2/O system, the TOXCHEM simulation is the best choice for the plant's decision-makers.

Keywords: biodegradation, Karbala STP, sewage treatment, TOXCHEM model.