Preliminary dexidation-anaerobism-oxygen deficit-multistage aerobic/anaerobic biological N and P removing method and device

Abstract

The invention relates to a preliminary dexidation-anaerobism-oxygen deficit-multistage aerobic / anaerobic biological N and P removing technology, including the steps: a) deoxygenation denitrification is carried out on returned sludge and part of sewage; b) anaerobic phosphorus releasing is carried out on the mixed liquid and part of sewage treated by the step a; c) denitrification is carried out on the mixed liquid and part of sewage treated by the step b and returned nitrification liquid; d) synchronous nitrification denitrification and decarbonising phosphorous absorption is carried out on the mixed liquid treated by the step c; e) nitrification liquid treated by the step d is returned to the step c; f) nitrification liquid treated by the step d is precipitated, part of sludge is returned to the step a, excess sludge is discharged, clean water is discharge or recycled after reaching standards. The device comprises a preliminary dexidation tank, an anearobism tank, an anaerobic tank, a multistage aerobic / anaerobic tank and a secondary sedimentation tank which are sequentially communicated; wherein the multistage aerobic / anaerobic tank is internally provided with a suspension chain aeration system, an inflow water distributing pipeline is connected with the preliminary dexidation tank, the anaerobism tank and the anaerobic tank, and sludge reflux quantity and nitrification liquid reflux quantity can all be regulated by a refluxing device.

Description

technical field [0001] The invention belongs to the technical field of environmental engineering, and specifically relates to a sewage treatment method and device, more specifically to a pre-deoxygenation-anaerobic-anoxic-multistage aerobic / anoxic biological nitrogen and phosphorus removal process and device . Background technique [0002] Anaerobic-Anoxic-Oxygen, A 2 O) is currently one of the most widely used technical solutions in sewage treatment projects, which can not only remove organic pollutants, but also remove nitrogen and phosphorus at the same time. Traditional A 2 The O process consists of anaerobic zone, anoxic zone, aerobic zone, sedimentation zone and sludge return and nitrification liquid return system. Sewage first enters the anaerobic tank and mixes with the returning phosphorus-containing sludge. Phosphorus accumulating bacteria absorb organic matter to synthesize PHB (poly-β-hydroxybutyric acid) and store it in the cells. At the same time, they hydro...

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Problems solved by technology

[0003] A 2 Since the O method began to be applied in China in the 1990s, the sewage treatment plant has been facing the problem that it cannot guarantee the efficient nitrogen and phosphorus removal effect at the same time in the actual operation: either the nitrogen removal effect is good but the phosphorus removal rate is low; the phosphorus removal effect Good, but the denitrification effect is not satisfactory

[0004] Existing A 2 The main problems that are difficult to solve in the O process are: 1. The return sludge will bring a large amount of nitrate nitrogen into the anaerobic tank, and the denitrification will seriously affect the anaerobic phosphorus release of phosphorus accumulating bacteria.

2. The carbon source problem of anaerobic pond and anoxic pond

3. The concentration of dissolved oxygen (DO) in the aerobic pool

Therefore, the high concentration of dissolved oxygen in the internal reflux nitrification mixture will cause the dissolved oxygen in the anoxic tank to exceed 0.5mg / L, which will seriously affect the full progress of the denitrification reaction

4. The problem of sludge age

However, the sludge age of phosphorus accumulating bacteria and denitrifying bacteria is generally within 10 days. During the operation, increasing the sludge discharge will help improve the phosphorus removal effect, but this will lead to a shorter sludge age, thereby inhibiting the The growth and reproduction of nitrifying bacteria with a long generation cycle will result in poor nitrification effect, which will affect denitrification and denitrification; on the contrary, the denitrification effect will be good, but the phosphorus removal effect will be poor

5. In actual engineering, because the treatment process cannot be adjusted, the operating conditions often deviate greatly from the design conditions, which will cause low or overloaded operation of the sewage plant, resulting in low treatment efficiency and poor treatment effect

[0005] With the continuous improvement of the discharge water quality standards of urban sewage treatment plants, especially the stricter requirements for nitrogen and phosphorus indicators, many cities and towns are required to adopt the A standard of the first-level standard of GB18918-2002, and the conventional secondary biological treatment process for sewage (such as A 2 O method) it is difficult to simultaneously control denitrification and phosphorus removal to such a high standard

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