Treatment of ammonia nitrogen in SBR tanks
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The current process involves contact anaerobic treatment followed by an SBR tank; the ammonia nitrogen level in the anaerobic stage is over 150, while it’s over 120 in the aerobic stage. The pH value ranges from 8 to 8.5. The COD level before entering the aerobic tank is 2500, and it drops to around 400–500 in the aerobic tank. Phosphorus is added to ensure an adequate supply of this element. The sludge concentration is 4–5 g, and the dissolved oxygen level is 5–6. How can ammonia nitrogen levels be reduced through adjustment? SBR operates in two shifts: aeration takes place from 6:30 a.m. to 4 p.m., followed by sedimentation until 7 p.m., after which water is drained; then water is added again for aeration until 4 a.m., followed by sedimentation and water drainage.
The conditions for biological removal of ammonia nitrogen are: 1. The presence of nitrifying bacteria, and the conditions for the presence of these bacteria are an appropriate temperature of 15–35°C； The appropriate pH range is 6.5–8; when it falls below 6.5, the nitrifying bacteria cease to function, so alkalinity is generally added to raise it ； Higher sludge age, with SRT greater than 20 days ； 2. Sufficient dissolved oxygen, with DO greater than 2 mg/L ； 3. Lower substrate concentration – the lower the BOD5, the better, generally not exceeding 50 mg/L;