Advantages of traditional activated sludge process

The growth of microorganisms is generally in the late logarithmic growth period or the stable growth curve. Because the aeration time of the ordinary activated sludge process is relatively long, when the activated sludge continues to advance to the end of the aeration tank, the organic matter in the wastewater is almost exhausted, and the sludge microorganisms enter the endogenous metabolism stage, and their activity ability is correspondingly weakened, so it is easy to precipitate in the sedimentation tank, and the amount of residual organic matter in the effluent is small. After the hungry sludge returns to the aeration tank, it has a strong adsorption and oxidation effect on organic matter, so the removal rate of BOD and suspended matter by ordinary activated sludge method is very high, reaching about 90 ~ 95%.

The common activated sludge process also has its shortcomings, mainly as follows: ① the adaptability to water quality changes is not strong; ② The supplied oxygen can't be fully utilized, because the front end of the aeration tank has high wastewater concentration, heavy sludge load and high oxygen demand, while the back end, on the other hand, is often evenly distributed along the length of the tank, resulting in insufficient oxygen supply at the front end and excessive oxygen supply at the back end (see Figure 4-2). Therefore, when treating the same amount of water, compared with other types of activated sludge process, the aeration tank is larger, occupies more land and consumes more energy.