Sewage denitrification and dephosphorization device and process based on improved AAO

Abstract

The invention relates to a sewage denitrification and dephosphorization device and process based on improved AAO. The device includes an anoxic selective tank, an electrolytic tank, an anaerobic tank,an anoxic tank, an aerobic tank and a secondary settling tank which are arranged in order along the sewage flowing direction. An operation mode of feeding water at multiple points of the anoxic selective tank, the electrolytic tank and the anoxic tank is achieved. Before returned sludge is returned to the anaerobic tank, the anoxic selective tank is additionally arranged, thus reducing or eliminating influences of nitrates on anaerobic phosphorus releasing. The electrolytic tank is additionally arranged on a water feeding pipeline of the anaerobic tank, and the residence time is generally controlled within half an hour, and therefore, on the one hand, dissolved oxygen in the sewage can be consumed while preserving sufficient carbon sources, ensuring that the sewage entering the anaerobictank meets anaerobic conditions; and on the other hand, a situation that the sewage in the anaerobic tank is influenced by a low pH and further effective phosphorus release of phosphorus-accumulatingbacteria, nitrification of nitrifying bacteria and denitrifying denitrification of denitrifying bacteria are influenced can be avoided. Quality indicators of discharged water by the device and the process all meet and exceed the national emission standard level A standard in China.

Description

technical field [0001] The invention relates to the technical field of sewage treatment, in particular to an improved AAO-based sewage nitrogen and phosphorus removal device and process. Background technique [0002] The A / A / O process is called the combination system of anaerobic-anoxic-aerobic. As early as the 1970s, the United States developed a simultaneous phosphorus and nitrogen removal wastewater treatment process on the basis of biological nitrogen removal methods. [0003] Biological phosphorus removal is a microorganism that uses phosphorus-accumulating bacteria. This microorganism can excessively absorb phosphorus from the external environment in quantities that exceed its physiological needs. System, to achieve the effect of phosphorus removal from sewage. Under anaerobic conditions (DO=0, NO3-=0), the ATP in the phosphorus accumulating bacteria undergoes hydrolysis, releases H2PO4, forms AOP and releases energy at the same time. Therefore, phosphorus accumulat...

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Problems solved by technology

The conventional A / A / O process has the following disadvantages: 1. Because the anaerobic zone is in the front, the nitrate in the return sludge will have an adverse effect on the anaerobic zone, affecting the phosphorus removal effect of the system; 2. Since the anoxic zone is located in the system In the middle, denitrification is in a disadvantageous position in the distribution of carbon sources, thus affecting the denitrification effect of the system; 3. Due to the existence of internal circulation, only a small part of the remaining sludge discharged by the conventional process system has actually undergone complete phosphorus release , Phosphorus uptake process, and the rest basically go directly from the anoxic zone to the aerobic zone without anaerobic state, which is unfavorable for systemic phosphorus removal

Whether it is conventional A / A / O, or improved A / A / O process, inverted A / A / O process, UCT process, MUCT process, most of the sewage is directly sent to the anaerobic tank for anaerobic release. Phosphorus, because the sewage itself contains a certain dissolved oxygen value, or the pH value is unstable, resulting in the failure to achieve the expected anaerobic conditions, which will affect the effective anaerobic release of phosphorus by phosphorus accumulating bacteria, and then lead to poor and unstable phosphorus removal

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