A pilot scale research on nitrification control parameters and energy saving by applying frequency conversion technology on controlling DO of SBR

Key words: 
• SBR /
• frequency conversion technology /
• DO /
• pH

Abstract: The adjustment of aeration rate based on the oxygen demand of microorganism in aerobic reaction is very critical under the condition of current energy shortage. In order to investigate the effect of aeration rate adjustment on the controlling parameters of SBR, such as pH value and DO, frequency converter was used to adjust the aeration rate and control DO at different levels. 60 m3 volume SBR reactor was used to treat the domestic wastewater of Beixiaohe WWTP in Beijing. It was investigated that the relationship between the parameters such as pH value and DO in the nitrification process and the process of organic degradation and nitrification. A new control parameter-frequency of frequency converter, called f for short, was also introduced. According the results, when the controlled DO concentration is low, the pH value could not be used as control parameter of nitrification completion, but the judgment of the complete nitrification could be based on the frequency. When the DO concentration was controlled at 3.0 mg/L and 4.0 mg/L respectively, DO, pH value and frequency of converter could be used as the control parameters of complete nitrification. The frequency controlling can also decrease the energy consumption of the blower per hour effectively.