Nitrogen removal from wastewater via shortcut nitrification-denitrification achieved by controlling pH

A novel technology for nutrient removal from wastewater was developed using the sequencing batch reactor(SBR) activated sludge process.Nitrogen removal can be achieved at 28±1 ℃ via shortcut nitrification and denitrification by controlling the pH value at 7 8-8 7.The experimental results indicated that nitrite was the main element in the effluent when aeration was ended after twenty-five days,that nitrate was less than 4 mg/L,and that the nitrosation rate(NO_2~——N/NO_x~——N) was more than 90%.In addition,as free ammonia(FA) concentration was always at 0 52-4 72 mg/L during nitrification,it would inhibit the nitrite oxidizers.So the shortcut mechanism achieved in nitrification-denitrification by controlling the pH value is that using the inhibition of the nitrite oxidizers to raise pH value and free ammonia results in accumulation of the nitrite.