Biological nitrogen and phosphorus removal method and system for sewage

Abstract

The invention relates to the field of water treatment, in particular to a biological nitrogen and phosphorus removal method and system for sewage. The method comprises the following steps: 1) performing anaerobic treatment on a to-be-treated water body; 2) carrying out anoxic treatment on the water body obtained by anaerobic treatment; 3) carrying out aerobic treatment on the water body obtained by anoxic treatment; 4) carrying out oxygen elimination treatment on the water body obtained by aerobic treatment; 5) refluxing a part of supernatant of the water body obtained by oxygen elimination treatment to the step 2) for anoxic treatment; 6) carrying out membrane-based biological treatment on part of supernatant of the water body obtained by oxygen elimination treatment; 7) carrying out precipitation treatment on a lower-layer mud-water mixture of the water body obtained by the oxygen elimination treatment; 8) refluxing part of the water body obtained by the membrane-based biological treatment to the step 1) for anaerobic treatment; and 9) refluxing part of the water body obtained by the membrane-based biological treatment to the step 3) for aerobic treatment. The method is good in removal effect of total nitrogen and total phosphorus pollutants, simple and convenient to operate, low in energy consumption and stable in up-to-standard emission.

Description

technical field [0001] The invention relates to the field of water treatment, in particular to a method and system for biological denitrification and dephosphorization of sewage. Background technique [0002] With the rapid development of my country's economy, the problem of water pollution is becoming more and more serious. In 2018, the total amount of sewage generated in my country reached 70.8 billion tons, of which domestic sewage accounted for 74.4%, becoming the main source of sewage. Domestic sewage is often rich in nitrogen and phosphorus pollutants. In 2015, the total discharge of ammonia nitrogen in my country's urban domestic sewage reached 1.341 million tons, accounting for 60% of the total discharge of all types of sewage. Therefore, the problem of nitrogen and phosphorus removal is still a major challenge for my country's sewage treatment industry. Therefore, efficient removal of nitrogen and phosphorus from sewage is still a major challenge for my country's...

AI Technical Summary

Problems solved by technology

This kind of traditional biological treatment technology is mature and easy to operate, but it often faces the problem of unstable denitrification and phosphorus removal process and limited deep nitrogen and phosphorus removal capacity

In particular, my country's sewage treatment plants often face low COD in sewage. Since the denitrification process needs to consume carbon sources, when the carbon source in sewage is insufficient, the addition of carbon source not only increases the treatment cost, but also may bring the risk of excessive COD in the effluent.

Therefore, as nitrogen and phosphorus discharge standards become increasingly stringent, it becomes increasingly difficult for sewage treatment plants to achieve high standards of discharge

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