Temperature is an important control parameter for sewage plants, especially in the North. In response to changes in temperature, sewage plants should take the initiative to manage operations rather than passively make adjustments. Only by understanding the laws of nature and the microbial habits, can we better utilize the characteristics of activated sludge, so that the sewage treatment can reach the standard under the environmental conditions as temperature changes.


 
Sewage treatment relies heavily on the activities of microorganisms. When the water temperature rises by 10 degrees Celsius, the microbial activity will double. When the influent temperature is high and the microbial activity is doubled, the degradation ability of the microorganisms increases after the microbial activity increases. When the degradation ability increases, the oxygen is absorbed more quickly in the aeration tank at a higher temperature in summer. So, it is necessary to supply air to the aeration tank at a higher rate and with a larger volume. At temperatures in summer, organic matter in the water will degrade faster and the regeneration rate of activated sludge will increase. Therefore, in summer, it is necessary to increase sludge discharge and slow down the aging of activated sludge.


 
In winter, the activity of microorganism decreases, resulting in a decrease in oxygen consumption in biological reactions, and it is unnecessary to supply air quickly. However, due to the slowdown of microbial activity, organic pollutants in the influent take longer to degrade, so it takes longer to process in the colder months. In practical applications, if there are reserved spaces, more treatment structures can be used in winter to extend the residence time to compensate for the effects of reduced activity.