In comparison to CSTR(Continuous-Stirred Tank Reactor) and PFR(Plug Flow Reactor), SBR(Sequencing Batch Reactor) has many advantages including low sludge production, flexibility of operation, efficient nutrient(Nitrogen and phosphorus) removal. SBR, however, could be more economical by design criteria.
In this research, three phase experiments were performed for investigating the hydraulic characteristics and nutrient removal capabilities of SBR. In the first experiment, three reactor systems were used to compare the HRT(Hydraulic Retention Time) of SBR with CSTR and PFR. Aeration tank volumes of CSTR and PFR were 3 liters each, and effective and total volumes of SBR were 3 and 4 liters, respectively. In the second experiment, substrate removal efficiencies in SBR were observed regarding various operating conditions such as fill time. And in the third experiment, the nitrogen removal characteristics in the biological excess phosphorus removal systems were investigated, in SBR whose effective and total volumes were 0.6 and 1.0 liter, respectively. The operating time of aerobic, anaerobic and anoxic were 3, 4 and 3 hours, respectively.
The followings were found in this study.;
1. HRTs of ideal CSTR and PFR showed extreme values. However, HRT of SBR was the intermediate closer to that of PFR.
2. The ratio of fill to react periods in SBR influenced much on substrate removal efficiency. Substrate concentration in SBR kept low during the fill of 5 hours. And the hydraulic performance of SBR was enhanced as the fill time decreased.
3. In the third test, the removal efficiency of substrate(mixture of starch and milk powder) was above 85% during anaerobic period. Excess phosphorous release and uptake appeared in one month operation, however, phosphorus re-released during the anoxic period when total kjeldahl nitrogen was below 45 mg/L. The phosphorus release in this period was due to the change of anoxic into anaerobic condition resulted from the complete denitrification of oxidized nitrogen.
4. Nitrogen concentration has little influence on excess phosphorus release and uptake. So as to remove nitrogen and phosphorus simultaneously, anoxic period must be not anaerobic conditions maintained before effluent discharge.
