Nitrogen and phosphorus removal using sequencing batch reactor

Abstract

In this research, investigations were made on material transfer mechanisms and optimum operation mode for sequencing batch reactor(SBR) system removing phosphorus and nitrogen simultaneously. Phosphorus release characteristics were expressed in the Monod equation, in which the reaction rate was replaced with specific phosphorus release(SPR) rate. The rate of SPR was increased during the first 80 days, but increased sharply reach 0.003 $hr^{-1}$ afterwards. Phosphorus removal efficiencies were about 60\% in the first 80 days, 75\% after 80 days, and above 95\% after 120 days. After 120 days, phosphorus concentration in the effluent was below 0.5 ${mgl}^{-1}$ when 8 ${mgl}^{-1}$ in the influent and the released phosphorus after 3-hour-anaerobic period was 60 ${mgl}^{-1}$. SBR, which shows the similar hydraulic characteristics to the combination of continuous-flow stirred tank reactor(CFSTR) and plug flow reactor (PFR) has the redundant time periods, such as SETTLE and DRAW not involved in bioreation. Theses defects of SBR, however, can be overcome by its versatile hydraulics and less land requirement. SBR hydraulics is suitable for some wastewater generated intermittently over other reactors system. SBR has many other advantages, such as having readily settlable sludge, being able to omit final settling tank, and adaptability to various operating conditions, From the computer simulation and experimental results, the hydraulic characteristics of SBR show the interim between PFR and CFSTR at the higher substrate removal rate, and FILL time in SBR system is an important factor to affect the SBR hydraulics, and the shorter FILL time enhances the SBR hydraulics. The method to develop excess phosphorus removal system was proposed. Biological excess phosphorus removal system could be achieved in a week and showed good performance and stability on the proposed operation method. From these results, several assumptions made in the research for biological excess phosphorus ...