Sewage nitrogen and phosphorus removal method and device

Abstract

The invention discloses a sewage nitrogen and phosphorus removal method and device. The method comprises the following steps: S1, biological phosphorus removal treatment; S2, precipitation treatment; S3, biological denitrification treatment; and S4, re-precipitation treatment: carrying out re-precipitation treatment on the effluent treated in the step S3, separating to obtain supernate II and sludge II, and discharging the supernate II as effluent, wherein the sludge age of the sludge in the biological phosphorus removal treatment process is adjusted to be t1, the sludge age of the sludge in the biological nitrogen removal treatment process is adjusted to be t2, t1 and t2 are positive numbers, and t1 is not larger than t2. According to the method, nitrogen removal and phosphorus removal are separated, the influence of nitrate reflux in the traditional process on phosphorus release under anaerobic conditions is avoided, the treatment time of the two steps of phosphorus removal and nitrogen removal is adjusted respectively, and target flora is reserved to the maximum extent, so that removal of N and P is better realized, additional energy sources are not consumed, and the production cost is saved.

Description

technical field [0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a method and device for denitrification and dephosphorization of sewage. Background technique [0002] After urban sewage undergoes traditional secondary treatment, although most of the suspended solids and organic matter are removed, there will still be traces of suspended solids and dissolved harmful substances, such as nitrogen and phosphorus. Although nitrogen and phosphorus are important nutrient sources for organisms, with the widespread use of chemical fertilizers, detergents and pesticides, the nitrogen and phosphorus content in natural water bodies has increased sharply, and cyanobacteria and green algae in water bodies have proliferated, resulting in hypoxia in water bodies and the production of toxins , worsen the water quality, and cause great harm to aquatic organisms and human health. Therefore, it must be controlled. [0003] Nitrogen and pho...

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Problems solved by technology

Therefore, there is a contradiction between nitrifying bacteria and phosphorus accumulating bacteria in terms of sludge age, that is, long sludge age is beneficial to nitrification but not conducive to biological phosphorus removal; short sludge age is beneficial to biological phosphorus removal but not conducive to nitrification; (2 ) The denitrification process and the phosphorus removal process have competition and contradictions in the reaction substrate (carbon source) and reaction space, it is difficult to obtain a good effect of N and P removal at the same time, and usually a large amount of additional energy is required to obtain a satisfactory effect; ( 3) The aggregation degree of microbial aggregates in the sewage biological treatment system. Compared with the traditional activated sludge method, granular sludge has good settling performance, contains more biomass, less residual sludge, and has simultaneous nitrification and denitrification and phosphorus removal. Dephosphorization and other functions, but the stability of the granular sludge system is poor, and the influencing factors include particle size, shape, sedimentation, density, strength, microbial structure differences, extracellular polymers, etc.

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