Aubert oxidation ditch process characteristics:
Aubert oxidation ditch is an activated sludge method of delayed aeration method, the ditch body usually consists of three concentric oval ditch, sewage and reflux sludge mixing, from the outer ditch into the ditch, and then into the middle ditch and the inner ditch in turn, in the ditch in the circulation of dozens of times to hundreds of times, and ultimately the water outlet to the second sedimentation tank. Each channel is installed with a varying number of rotating disk aerators for oxygenation and push-flow mixing.
Compared with the ordinary oxidation ditch, Aubert oxidation ditch can be regarded as a kind of multi-stage oxidation ditch by the outer ditch, the middle ditch and the inner ditch in series:
The function of the outer ditch is mainly to complete the oxidation of the carbon source, denitrification and most of the nitrification with high efficiency, and the volume is usually accounted for 50% to 55% of the oxidation ditch, and it can remove about 80% of the organic matter, and the concentration of the dissolved oxygen is generally between 0mg/l and 0.5mg/l. Between 0mg/l ~ 0.5mg/l, the formation of alternating oxygen consumption and large areas of anoxic environment in the ditch, can be a high degree of simultaneous "nitrification and denitrification", the effect of denitrification is obvious, ammonia and nitrogen removal rate can be as high as 90%; at the same time, due to the majority of the area of the ditch in the 0mg/l ~ 0.5mg/l of dissolved oxygen between the oxygen transfer is carried out under oxygen deficit conditions. oxygen deficit conditions, the oxygen transfer rate is improved, energy saving effect is obvious.
The middle ditch is the transition section between the outer ditch and the inner ditch, complementary regulation, further removal of the remaining organic matter and continue to complete the nitrification of ammonia nitrogen, and can give full play to the outer ditch or the inner ditch to strengthen the role of the system is conducive to ensuring the reliability of the operation of the system, the middle ditch volume is generally accounted for 25% to 30% of the dissolved oxygen concentration is controlled at around 1.0mg / l. The middle ditch is generally used as a means of reducing the risk of contamination of the water.
The inner ditch is mainly to ensure that the oxidation ditch effluent water quality, dissolved oxygen concentration of about 2.0mg/l or so, in order to ensure that organic matter and ammonia nitrogen removal rate is higher, and at the same time to ensure that the effluent with enough dissolved oxygen to enter the second sedimentation tank, inhibit the release of phosphorus. The volume of the inner ditch is about 15% to 20% of the total volume of the oxidation ditch.
From the Aubert oxidation ditch three ditch of dissolved oxygen distribution, the outer ditch, the middle ditch, the inner ditch of dissolved oxygen was 0-1-2mg / L gradient distribution, of which, only the inner ditch of dissolved oxygen value of the requirements of the higher, with the ordinary oxidation ditch requirements (2mg / L) consistent with the outer ditch and the middle of the ditch of dissolved oxygen is lower than the ordinary oxidation ditch Requirements. As the transfer rate of oxygen with the reduction of dissolved oxygen concentration of the mixture and improve, so in the outer ditch and the ditch in the Aubert oxidation ditch, the transfer rate of oxygen will be higher than the ordinary oxidation ditch, so that the amount of oxygen can be reduced accordingly, which determines the Aubert oxidation ditch is more energy-efficient than the ordinary oxidation ditch, generally save energy consumption of about 15% to 20%. Therefore, in the design of Aubert oxidation ditch, should be fully integrated with the process characteristics, scientific and reasonable calculation of the amount of oxygen.