Modelling of sequencing batch reactor operating at various aeration modes

Abstract

The presented study involved designing a computer model of a sequencing batch reactor (SBR) at laboratory scale. The data pertaining to the technical aspects of the bioreactor and quality indicators of wastewater constituted the input for the employed simulation tool, i.e. GPS-X software package. The results of a simulation involving a 12-hour operation cycle are presented in this work; each cycle included 6 phases: filling, mixing, aeration, settling, decantation and idling (wasting of excess sludge). The simulations were carried out using two different modes of aeration. Concentration of dissolved oxygen (DO) was maintained at constant level of 2 mgO2/L using the PID controller in the first case. On the other hand, variation of DO concentration was employed in the aeration stage of the second variant, which was achieved using appropriately elaborated set point of oxygen concentration, considering the specific intervals in oxygen supply. The changes observed in DO concentration varied from 0.5 to 2.5 mgO2/L. This research proved that the second variant, involving variation of DO concentration, was characterised by reduced levels of pollution indicators in treated sewage, as well as lower consumption of electricity, both of which contributed towards improving the effluent quality and resulted in significant degree of dephosphatation.

Modeling and optimizations of mixing and aeration processes in bioreactors with activated sludge

“…In the systems with integrated removal of nutrients and carbon compounds, treatment processes are carried out under the anaerobic, anoxic and aerobic conditions. Therefore, the adequate aeration of activated sludge is of great importance, which, however, is also one of the most energyintensive processes in wastewater treatment plants [2,3,8]. Thus, research is largely focused on the search for more and more advanced solutions characterized by high energy efficiency, to ensure the required standards of wastewater treatment on the one hand, and to promote the reduction of operating costs on the other.…”

“…Good results are obtained by using alternating aeration, which allows the individual processes to take place under varying aerobic conditions [3,[17][18][19]]. The properly selected parameters of the aeration system in SBR bioreactors improve the structure of flocs, positively affecting their sedimentation capacity [3,8,18,20]. Therefore, the aeration phase is considered the most important stage of operation in SBR reactors [3,21].…”

“…Two basic groups of these devices can be distinguished: mechanical aeration devices and devices for aeration with compressed air [3,20,22]. The optimal solution is an aeration system characterized by high efficiency and low energy consumption while ensuring turbulence, which on the one hand causes full homogenization of the reactor, and on the other hand, does not tear or fragment the activated sludge flocs [3,8,23]. Aeration of the SBR bioreactor chamber can be realized using diaphragm disks or pipe diffusers which disperse compressed air delivered to the bottom of the chamber.…”