What is the activated sludge process?

The activated sludge process was founded by Englishmen Aden and Lokot in 19 14. This method has the advantages of high efficiency, good effect, strong practicability, low cost, large wastewater treatment capacity and mature method. Generally, this method is used in large sewage treatment plants with a daily treatment capacity of more than one million tons. This method can be divided into two types: plug flow aeration treatment and completely mixed aeration.

1. Push-flow aeration treatment means that wastewater and activated sludge enter the aeration tank at the same time and move forward until the end of the tank. At first, the concentration of organic matter in wastewater was high, and the bacteria in activated sludge were in logarithmic growth period. With the advancement of water flow, organic matter is continuously degraded, which makes the concentration of organic matter in water gradually decrease and the bacteria in sludge enter a static period. Finally, at the end of the pond, the organic matter is exhausted and the bacteria turn into the endogenous growth period. This method can make the bacteria in activated sludge go through the whole growth cycle in the pond, so the purification effect is good and stable.

2. completely mixed aeration method means that the primary wastewater and the return sludge are fully mixed with the original mixed solution in the aeration tank immediately after entering the aeration tank, so that the concentrated wastewater can be well diluted. Therefore, this treatment method can bear a large impact load, and the oxygenation is relatively uniform. However, due to the short residence time of wastewater in the pond, bacteria are always in logarithmic growth period, and the treatment effect is generally not as good as plug flow.