Activated Sludge Model No. 1 (ASM1) applicability for simulation of sanitary sewage and landfill leachate co-treatment in aerated lagoons

The growing necessity for alternative landfill leachate treatment and disposal is a reality in Brazil, mainly when the advancements of the National Policy on Solid Wastes (2010) established goals for replacing dumping grounds with landfills. Due to its simplicity, a usual alternative is to perform co-treatment of municipal sewage and landfill leachate in wastewater treatment plants (WWTPs). This study assessed the applicability of the Activated Sludge Model No 1 (ASM1) to aerated lagoons promoting sewage and leachate co-treating. The simulated scenarios consisted of increasing proportions of leachate addition to the system, ranging from 0 to 10%, and for each of them the development of heterotrophic and autotrophic biomass, COD consumption in different fractions, nitrification, oxygen consumption and alkalinity were evaluated. The simulation results showed that the model was optimistic regarding the treatment system startup and microbial communities adaptation when exposed to increasingly aggressive conditions due to leachate addition. However, it correctly represented the detrimental effects on effluent quality due to recalcitrant organic matter and the issues with maintaining proper nitrification regarding aeration capacity and alkalinity demands. ASM1 has good applicability, therefore, as a tool to qualitatively assess the behavior of WWTP when receiving leachate for co-treatment and corroborates the risks associated with this alternative, however, requiring further modifications and details to optimize real systems.