Three full-scale municipal sequential batch reactor (SBR) wastewater treatment plants (WWTPs) were investigated by dynamic simulation studies using ASM1. All three WWTPs showed similar kinetic and stoichiometric conditions in the SBR population behaviour after calibration of the models. The simulation results detected only a discrepancy to the ammonia online data during and shortly after shock loading under anoxic and anaerobic conditions that so far could not be adjusted by the ASM1 model. However, these differences did not severely affect the quality of the simulations nor the effluent flows. Additionally, in all cases a dynamic alpha factor curve occurred during the aeration phases that was verified by further oxygen transfer measurements. This might reveal new aspects for the process control, design and simulation of SBR WWTPs. A short lag phase was detected in many cases at the beginning of the first aeration phase.
Significant NH4-N balance deficits were found during the measurement campaigns for the data collection for dynamic simulation studies at five full-scale sequencing batch reactor (SBR) waste water treatment plants (WWTPs), as well as during subsequent calibrations at the investigated plants. Subsequent lab scale investigations showed high evidence for dynamic, cycle-specific NH4+ ad-/desorption to the activated flocs as one reason for this balance deficit. This specific dynamic was investigated at five full-scale SBR plants for the search of the general causing mechanisms. The general mechanism found was a NH4+ desorption from the activated flocs at the end of the nitrification phase with subsequent nitrification and a chemical NH4+ adsorption at the flocs in the course of the filling phases. This NH4+ ad-/desorption corresponds to an antiparallel K+ ad/-desorption.One reasonable full-scale application was investigated at three SBR plants, a controlled filling phase at the beginning of the sedimentation phase. The results indicate that this kind of filling event must be specifically hydraulic controlled and optimised in order to prevent too high waste water break through into the clear water phase, which will subsequently be discarded.
Models for engineering design of nitrifying systems use one ammonia oxidizer biomass (AOB) state variable. A simple extension using two AOB populations allows a more accurate prediction of nitrification systems at switching process environments. These two AOB subpopulations are characterized by two different sets of kinetic parameters. Selection pressure and competition between the two functional AOB populations are determined by process conditions as demonstrated by three case studies: Case study I describes dynamics of two AOB populations showing different temperature sensitivities (modified Arrhenius term on growth and decay) when bioaugmented from the warm sidestream treatment environment to the cold mainstream and vice-versa. Case study II investigates competition between fast growing micro-strategists and k-strategists adjusted to low ammonia levels depending on the internal mixed liquor recycle rate (IMLR). Case study III shows that AOB transferred from the waste activated sludge of an SBR to the parallel continuous flow system with different decay kinetics can overgrow or coexist with the original population.
Increasingly stringent effluent limits and an expanding scope of model system boundaries beyond activated sludge has led to new modelling objectives and consequently to new and often more detailed modelling concepts. Nearly three decades after the publication of Activated Sludge Model No1 (ASM1), the authors believe it is time to re-evaluate wastewater characterisation procedures and targets. The present position paper gives a brief overview of state-of-the-art methods and discusses newly developed measurement techniques on a conceptual level. Potential future paths are presented including on-line instrumentation, promising measuring techniques, and mathematical solutions to fractionation problems. This is accompanied by a discussion on standardisation needs to increase modelling efficiency in our industry.
Dynamic simulation analyses of five different sequencing batch reactor (SBR) wastewater treatment plants (WWTPs) were used in order to optimise developed regulation strategies and to develop new strategies. The results were applied directly to 15 full-scale SBR plants. To do this, the cycle strategies were extended through the use of appropriate aggregates, or were anchored in the programmable logic controller (PLC) and process control system (PCS) with the help of online sensors. This enabled all regulation strategies to be introduced and automated without problems.
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