Nitrogen, phosphorus and other pollutants, a large number of emissions, further exacerbating the conflict of water shortage, therefore, the sewage discharge control is very important. Phosphorus, nitrogen emissions of large quantities of water, resulting in eutrophication of water, eventually leading to ecological balance, affecting human health and development and other hazards. The following describes the urban sewage treatment of nitrogen and phosphorus removal technology:
Treatment of urban sewage nitrogen and phosphorus use more A / O, A2 / O process, sequencing batch process, oxidation ditch series technology. The following is an introduction of several municipal wastewater phosphorus and nitrogen removal process.
1A2 / O method:
1) Traditional A2 / O method: The traditional A2 / O method is the commonly used technology of simultaneous denitrification and dephosphorization. It adds an anoxic section and an anaerobic section on the basis of the traditional activated sludge process
2) Inverted A2 / O process: it is an improvement on the traditional A2 / O process and has a better denitrification and dephosphorization effect. The reason for this is that the anoxic zone is located before the anaerobic zone, which is favorable for the microorganisms to form a stronger phosphorus-absorbing dynamic , After the anaerobic phosphorus release microbial directly into the aerobic environment full of phosphorus; all involved in the return of the sludge have undergone a complete release of phosphorus, phosphorus absorption process; anaerobic tank before the anaerobic tank to allow denitrification bacteria priority access Carbon source, thus strengthening the system's ability to denitrification
2 sequence batch process
1) The traditional SBR method: It is intermittent activated sludge method, which consists of one or more aeration reaction tank, the sewage into the pool in batches, after the activated sludge purification, the supernatant night out of the pool to complete a run cycle. SBR process is simple, less handling structures, aeration tank set aeration sedimentation sludge back in one, and the sludge less, easy to dehydration, but there are automatic control and continuous on-line analysis of high instrumentation requirements.
2) CASS process: It is a continuous influent SBR aeration system, which not only has the characteristics of simple and reliable SBR process, flexible operation mode and high degree of automation, but also obvious effect of nitrogen and phosphorus removal. This function is mainly achieved in the CASS pool through the wall of the reaction chamber will be divided into different functional areas, dissolved oxygen in each partition, the sludge concentration and organic load, the pool of different organisms, while in the traditional SBR pool Set before the selector or pool and anaerobic zone, improved nitrogen and phosphorus removal effect.
3 oxidation ditch process
Oxidation ditch process is a delayed aeration activated sludge method, due to the low load, impact load, water quality is good, less sludge production and stability, less structures, oxidation ditch can denitrification design, but also Can be slightly improved to achieve nitrogen and phosphorus removal. Oxidation ditch process is a simple process, management convenience, investment, low operating costs, high process stability of sewage treatment technology.
The above dephosphorization and denitrification technology can well solve the problem of excessive phosphorus and nitrogen, but sometimes the concentration of phosphorus and nitrogen in the effluent is not up to standard due to the interference of some factors. For this purpose, the dephosphorization agent can be added at the end of the treatment process Or ammonia nitrogen removal agent.
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