Relationship between aeration rate and temperature in the activated sludge process
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In the Bileke town sewage treatment process, what adjustments should be made as seasons change, given that the sludge concentration, aeration volume, and sludge return ratio remain constant. I’m from southern Hebei. Every year, during the transition from autumn to winter and from winter to spring, large amounts of sediment accumulate in the anaerobic tanks, aeration tanks, and sedimentation tanks. The COD and ammonia nitrogen levels in the effluent are still within acceptable ranges. What’s causing this? Please give me some advice. I began to analyze that when the temperature drops suddenly, the activity of the sludge decreases, and the amount of oxygen consumed also reduces; at such times, the aeration rate should be lowered. The opposite should be true when the temperature rises. But I’m not sure either, through practice, whether it’s correct. When the suspended sludge disappears, is it because the activated sludge has adapted to the environment, or does it disappear as a result of adjusting the aeration volume? The designed treatment capacity is 33,000 per day, while the actual treatment capacity is 20,000.
To resolve this issue first, it is necessary to understand the water inflow situation. The temperature of the water entering the contact oxidation tank in winter should be maintained between 15°C and 24°C. If this temperature range can be maintained, it is acceptable to keep the sludge concentration, aeration volume, and recirculation ratio constant in the contact oxidation tank. If the northern regions experience a significant drop in temperature and the anaerobic systems were not properly insulated beforehand, it will inevitably affect the efficiency of treatment in the contact oxidation tanks. The appearance color of the sludge in the contact oxidation tank may not change much, but its settling ratio will definitely increase, as filamental bacteria reproduce rapidly at low temperatures. This leads to an increase in sludge foam, and sludge bulking may occur. The solutions involve improving the insulation and heating in the anaerobic tank, increasing the aeration volume and sludge removal rate. If these issues cannot be resolved promptly, it is possible to spray disinfectants into the contact oxidation tank to kill bacteria and control the water inflow volume. Short-term aeration under pressure is necessary if required.