This study aimed at providing a set of optimal kinetic and stoichiometric parameters of ASM1 representative of wastewater from a subtropical climate region in Brazil. ASM1 was applied on the STOAT program, and the model parameters were evaluated and optimized with sensitivity analysis and Response Surface Methodology (RSM) to reach minimum prediction errors of effluent TSS, COD, and NH3. Six sensitive parameters were identified: YH, YA, μA, KNH, bA, and kOA. Predictions of RSM regression models were strongly correlated to the STOAT predictions. YH mainly affected TSS and COD, and the other parameters affected NH3. ASM1 calibration with estimated optimal values of sensitive parameters resulted in approximately null prediction errors for modeling state variables. NH3 presented similar results in the ASM1 validation; meanwhile, TSS and COD presented high errors related to the increase in YH due to the RSM optimization. The optimal parameters, mainly YA, μA, KNH, bA, and kOA, constitute references for other studies on ASM1 modeling using wastewater data from a subtropical climate region. YH optimal value should be evaluated as well as the effect of sludge wastage methods and the simulation periods.

This study aimed to verify the biological anaerobic treatability of tebuconazole effluent manufacturing. For this purpose, two preliminary batch tests were performed using an 'anaerobic respirometer' adjusting the initial pH of the effluent at 7.0 and 8.0, respectively (first phase). In addition, two tests (second phase) were run using sequential batch anaerobic fermenters, the first operated at different hydraulic detention times (10 and 16.7 days) and the second with different initial dilutions of the effluent (5 and 20%). The chemical oxygen demand (COD) removal observed on the anaerobic respirometer tests was in the range of 66-81%. According to the preliminary batch tests an optimal value of initial COD concentration and amount of biomass was identified, which was considered for the fermenters start up. However, it was observed that the optimal relation provided by the respirometer test was not a good parameter of operational control for the fermenters due to the accumulation of inhibitory substances, which affected the microbial activity and took the system to collapse. The initial dilution of the effluent (5 and 20%) was essential for the stability of the anaerobic system, allowing COD removals above 74% during this study.