|M.Sc Student||Birenbaum Haya|
|Subject||Biological Nutrient Removal by Sequencing Batch Reactor in|
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Emeritus Noah Galil (Deceased)|
|Full Thesis text - in Hebrew|
Sequencing batch reactor (SBR) is a fill-and draw activated sludge system characterized by a sequence of phases.
Mathematical models are usually being used for simulate/design/control activated sludge wastewater treatment system and ASM1/2/2D/3 is the most commonly used. The objective of this research was to develop a calculation model which could be used as a basis for the design of SBR systems for organic material and nutrients removal. The focus was on the bio- reaction phase which includes three main biological processes, anaerobic, aerobic and anoxic, necessary for organic material and nutrients removal. The model enables the examination of different parameters influencing the process, for a given quality of wastewater. The parameters examined in the frame of this study included: retention time / number of repetitions of the anoxic /aerobic bio-reaction phases, biomass concentration levels and feeding strategy. Different strategies were examined for the evaluation of two main cases of wastewater qualities: urban wastewater and industrial pretreated wastewater characterized by low concentration of organic material and nutrients. The cases were divided into four sub-cases with different C: N: P ratios. Different operation modes and the effectiveness of different feeding strategies were tested: one/multiple feeding events to the anoxic phases, one/multiple feeding events to the bio-reaction phases. There is no operational or quality advantage in the use of multiple feeding events over one feeding event. An anoxic feeding event did not produce the required effluent quality for both sources of the wastewater examined. The retention time required in the anoxic phase was found to be longer than in other bio-reaction phases due to the differences in ATP/NADH2 ratio. The model indicates that better removal of organic material can be achieved in case of longer retention times in the anaerobic phase. The retention time required for urban wastewater treatment is longer than for industrial pretreated wastewater; this could be explained by the higher concentrations of organic material and nutrients. According to the results, high biomass concentration / high sludge retention time (SRT) might be characterized by lower bio-activity and by additional loadings of organic and nutrients resulting from bio-solids decomposition.
In cases of low phosphorous concentration (less than 2 g/m3) the calculation model dose not simulate the real scenarios, the model should be expended in order to deal with those cases. This model could be a useful tool for the designer in finding the best operation mode for given quality of wastewater.