Evaluation of the Efficiency of the Sequencing Batch Reactor in Nitrogen and Phosphorus Removal from Synthetic Wastewater in a Bench Scale Experiment

The sequencing batch reactor (SBR) is one of the most widely used systems in sewage treatment because of the simplicity of the process, flexibility of operation in the removal of nutrients, and the ability to be used in different scales. The aim of this study was to evaluate the efficiency of the SBR in the removal of organic matter (nitrogen and phosphorus) from synthetic wastewater at laboratory scale.
In this study, a SBR with a capacity of 24 liters and 24-hour working cycle was used. The sequences of phases consisted of 30 minutes filling, 180 minutes aerobic, 120 minutes anaerobic, 900 minutes aerobic, 180 minutes anaerobic, 20 minutes settle, 5 minute decant, and 5 minutes idle. The initial concentration of nitrogen and phosphorus were 40 and 20 mg/l, respectively. The initial organic load was 0.41 to 0.83 kg chemical oxygen demand (COD)/m3/day. Sampling was carried out in the first aerobic phase and after the third hour anaerobic phase.
Findings: In this system, the average COD removal efficiency in the effluent during these six steps were 65.35%, 92.9%, 95.2%, 93.33%, 96%, and 96.5%, respectively. The results showed that the highest average removal efficiency of organic matter and phosphate phosphorus were 96.5% and 33.05%, respectively, in the sixth stage, and for nitrogen was 34.6% in the first stage.
The results showed the acceptable performance of the SBR in the removal of organic matter and nutrients (P, N).