Abstract

Sequencing batch reactors (SBR) are mainly characterized by sequential process phases of fill, react, settle, decant and idle periods that allow considerable flexibility in the design and operation in different conditions. This flexibility and the unique features of SBRs used to wastewater treatment by activated sludge systems operated in laboratory scale, allow not only conducting experiments for the standard conditions but also testing extreme situations during various processes. The design of an SBR bioreactors for nutrient (N,P) removal is mainly based upon the selection of some relevant parameters (e.g. sludge age, volume exchange ratio, cycle time, SVI) as described in, for instance, the ATV guidelines. Mathematical modeling and computer simulation of the existing WWTP provide an opportunity of introducing to the software present technology and examine many modifications, which do not require great financial costs and do not cause disturbances in the on-going processes. The computer model used for simulation could be calibrated and validated using data obtained from the experiment conducted with the use of laboratory scale device. This approach has the advantage that allows to reach important data, which cannot be achieved with technical full-scale WWTP. The aim of this study was to simulate the processes occurring in the SBR removing nutrients under varied aeration conditions. Within the study was presented the computer model simulating the operation of the SBR type reactor together with the results of the simulation concerning municipal wastewater treatment processes. The computer simulations results were used to evaluate the adaptation period of the biomass and biological wastewater treatment processes in SBR, as well as the period of breakdown of treatment process caused by the stoppage of raw wastewater inflow and turn off the aeration and/or mixing system. The biological processes described in the model were found to occur simultaneously under limited aeration conditions. A low oxygen transfer properly differentiates the system behavior from systems under traditional design calculations. As a result, the oxygen transfer should be strictly incorporated in the calibration of biological nutrient removal to visualize the individual contributions of each process.

Authors (4)