History of mainstream wastewater treatment technology

The research and application of AB process in our country have experienced three stages. Firstly, the characteristics, operation mechanism and stability of AB process are reported and studied in detail. Secondly, more units have conducted a certain scale of experimental research on the treatment of municipal sewage and industrial wastewater by AB process. Third, some domestic urban sewage treatment plants such as Shandong Qingdao Haipohe sewage treatment plant, Tai 'an sewage treatment plant, Xinjiang Urumqi Hedong sewage treatment plant, etc., on the basis of the introduction of German AB process technology, built a considerable treatment scale of AB sewage treatment plant. Compared with traditional activated sludge process, AB process has advantages in treatment efficiency, operation stability, project investment and operation cost.

(1.4) Development of A/A/O series

In the mid-1970s, Spector in the United States found that the alternating cycle of anaerobic/aerobic (Ap/O) states could not only effectively prevent the expansion of activated sludge filamentous bacteria, improve the settling performance of sludge, but also significantly enhance the effect of phosphorus removal. The first productive Ap/O (Anaerobic/Oxic) unit was put into operation in 1979. Many anaerobic/oxic treatment plants have since used this process. The AP/O system is composed of activated sludge reaction tank and secondary sedimentation tank, and the sewage and sludge flow successively through anaerobic and aerobic alternating circulation. The reaction pool is divided into anaerobic and aerobic zones, and the two reaction zones are further divided into cells with the same volume to produce a push flow state. The return sludge into the anaerobic tank can absorb and remove part of organic matter and release a large amount of phosphorus, and into the sewage of the aerobic tank can make the organic matter get aerobic degradation, at the same time, the sludge will absorb a large amount of phosphorus in the sewage, and part of the phosphorus-rich sludge is discharged in the form of residual sludge to achieve phosphorus removal.

AN/O (Anoxic/Oxic) process is a pre-denitrification biological nitrogen removal process with reflux, in which pre-denitrification is carried out in an anoxic tank and nitrification is carried out in an aerobic tank.a