How to restore the biochemical system as quickly as possible?
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The biochemical system is now malfunctioning; it is initially suspected that bacterial death has been caused by sludge poisoning. The contaminated water has been isolated, and water is still being supplied as usual. The following problems are now occurring: 1. The system’s nitrogen removal efficiency has declined; there is no nitrification in the main aerobic tanks, and no reduction in ammonia nitrogen levels at all. The fan speed is very low, yet the DO level easily reaches 3-4 mg/l. 2. Currently, the sludge has poor settling properties, with an SV of 70% and an MLSS of only 2000 mg/l. 3. Our process consists of anaerobic, anoxic, aerobic, two-stage anoxic, two-stage aerobic phases, followed by a sedimentation tank. Currently, the DO level in the first aerobic phase is 3–4 mg/L, while it is below 1 mg/L in the second aerobic phase. Increasing the fan frequency raises concerns that the DO level in the first aerobic phase might become too high; on the other hand, if the fan frequency isn’t increased, the DO level in the second aerobic phase remains too low. This can cause the sludge in the sedimentation tank to become smelly and black. What is the best course of action? 4. If nitrate bacteria die, how can they be quickly cultured again? pH value and DO are understandable, but it seems that the incubation time is too long. Do adjustments need to be made for internal recirculation and external recirculation? 5. The sludge load in the aerobic tank is around 0.1; currently, the MLSS level is about 2000. Should the amount of sludge removed be increased or decreased? I did the calculations: the sludge age in the aerobic tank is 44 days. But with the current low sludge concentration, if more sludge is removed, could that prevent the nitrifying bacteria from growing?
1. There is virtually no removal of ammonia nitrogen, and nitrification does not occur; it is necessary to cultivate nitrifying bacteria. The fan frequency is low, and the DO level is still at 3-4 ppm; it is recommended to calibrate the DO probe. 2. Sludge bulking may have occurred. 3. Adjust the air volume for the first stage of aerobic treatment and the second stage of aerobic treatment through valves, in order to control the DO levels in each stage. 4. Sludge cultivation requires a step-by-step approach; even after adding microbial strains, there is still a process of acclimatization required – it’s not possible to achieve the desired results immediately. External return flow and internal flow are adjusted according to operating conditions. 5. Is it also 0.1 when operating at full load? If you plan to cultivate nitrifying bacteria, then do not remove sludge and continue to increase the sludge concentration. This is my personal opinion for reference only.