Effect of Internal Recycle Ratio on the Phosphorus Removal Efficiency of Anaerobic/Anoxic/Oxic (A2/O) to Low Concentration of Organic Substance Wastewater

In the pilot-scale plant, the effect of internal recycle ratios (300%, 200%, 100%, and 0%) on the biological phosphorus removal was represented. The denitrifying phosphorus removal in anoxic tank was improved with low internal recycle, under the inhibition of high concentration of NOx-N. To low level strength wastewater (average COD 185.6 mg/L, average BOD 115.2 mg/L), the low level carbon source maintained the relatively steady phosphorus removal rates.