Modelling a full scale membrane bioreactor using Activated Sludge Model No.1: challenges and solutions

摘要

A full-scale membrane bioreactor (1,600m3nd21n) was monitored for modelling purposes during thensummer of 2006. A complete calibration of the ASM1 model is presented, in which the key pointsnwere the wastewater characterisation, the oxygen transfer and the biomass kinetics. Total BODntests were not able to correctly estimate the biodegradable fraction of the wastewater. Thereforenthe wastewater fractionation was identified by adjusting the simulated sludge production rate tonthe measured value. MLVSS and MLSS were accurately predicted during both calibration andnvalidation periods (20 and 30 days). Because the membranes were immerged in the aerationntank, the coarse bubble and fine bubble diffusion systems coexisted in the same tank. Thisnallowed five different aeration combinations, depending whether the 2 systems were operatingnseparately or simultaneously, and at low speed or high speed. The aeration control maintainednlow DO concentrations, allowing simultaneous nitrification and denitrification. This made itndifficult to calibrate the oxygen transfer. The nitrogen removal kinetics were determined usingnmaximum nitrification rate tests and an 8-hour intensive sampling campaign. Despite thenchallenges encountered, a calibrated set of parameters was identified for ASM1 that gave verynsatisfactory results for the calibration period. Matching simulated and measured data becamenmore difficult during the validation period, mainly because the dominant aeration configurationnhad changed. However, the merit of this study is to be the first effort to simulate a full-scalenMBR plant.