A2O process wastewater treatment equipment

1. Process:

The AAO process is mainly anaerobic, hypoxic and aerobic. The previous process has been running for so many years. But there are shortcomings. Anaerobic (phosphorus removal), hypoxic (denitrification), aerobic (nitrification).

Anaerobic cannot meet the anaerobic conditions (dissolved oxygen is high) Hypoxia is also difficult to meet the conditions (dissolved oxygen problem), to be anaerobic, and the hypoxia is poor later; Severe hypoxia and poor anaerobic conditions.

There is now an improved inverted AAO process. First hypoxia, then anaerobic, and finally aerobic. It adopts two points of water inlet and three points of reflux. It is very reasonable. Not only phosphorus removal and nitrogen removal have achieved very satisfactory results.

2. Working principle:

The biological pool is divided into anaerobic, anoxic and aerobic sections through the arrangement of aeration devices, thrusters (anaerobic and hypoxic sections) and return channels.
In this process, BOD5, SS and nitrogen and phosphorus in various forms are removed one by one. In the activated sludge of the A2O biological nitrogen and phosphorus removal system, the bacterial flora is mainly composed of nitrifying bacteria, denitrifying bacteria and polyphosphorus bacteria.

In the aerobic section, nitrifying bacteria convert ammonia nitrogen and organic nitrogen into nitrate through biological nitrification. In the hypoxic section, denitrifying bacteria convert the nitrate brought in by the internal reflux into nitrogen and escape into the atmosphere through biological denitrification, so as to achieve the purpose of nitrogen removal.

In the anaerobic section, polyphosphorus bacteria release phosphorus and absorb easily degradable organic matter such as low-grade fatty acids. In the aerobic section, polyphosphorus bacteria absorb excessive phosphorus and remove phosphorus through the discharge of remaining sludge.

3. Advantages

(1) The organic cooperation of three different environmental conditions and types of microbial flora of anaerobic, anoxic and aerobic can have the functions of removing organic matter, removing nitrogen and phosphorus.

(2) In the process of simultaneous deoxidation and phosphorus removal to remove organic matter, this process is the simplest, and the total hydraulic residence time is less than that of other processes in the same category.

(3) Under the alternating operation of anaerobic-hypoxic-aerobic, filamentous bacteria will not multiply in large numbers, and the SVI is generally less than 100, and sludge expansion will not occur.

(4) The phosphorus content in the sludge is high, generally more than 2.5%.