Wastewater pretreatment method and sewage treatment method using the pretreament method

A sewage treatment method, comprising the following steps:

• (1) introducing a wastewater feed into a first end of a first aeration basin to mix with a first concentrated mixed liquor to obtain a first mixed liquor;
• (2) aerating the first mixed liquor in an aeration section of the first aeration basin to obtain a second mixed liquor at a second end of the first aeration basin;
• (3) introducing the second mixed liquor to a first sedimentation basin to perform a sedimentation treatment to obtain a supernatant liquid and the first concentrated mixed liquor;
• (4) discharging the supernatant liquid, and returning at least a part of the first concentrated mixed liquor to the first end of the first aeration basin so as to have a sludge age of greater than 50 days, wherein the ratio of the aeration treatment time of the first aeration basin to the sedimentation treatment time of the first sedimentation basin is 1:0.5 to 1:6;
• and
• (5) passing the supernatant liquid through a biologic regulation zone, a second aeration zone and a second sedimentation zone in turn to obtain a first water effluent and a second concentrated mixed liquor, and returning a first part of the second concentrated mixed liquor to the biologic regulation zone.