Alternate combined wetland system and method for efficiently removing nitrogen and phosphorus in urban wastewater

Abstract

The invention discloses an alternate combined wetland system and a method for efficiently removing nitrogen and phosphorus in urban wastewater, belonging to the field of wastewater treatment. The system comprises a water taking system which is characterized by sequentially distributing four artificial wetland structural units of vertical composite flow, surface flow, underflow and an ecological pond. The water taking system enables the urban wastewater to uniformly flow into the artificial wetland of vertical composite flow; the entering domestic wastewater is uniformly distributed in a shape like the Chinese character 'wang(surname)', the discharged water enters the front end of the wetland structural unit of surface flow, the back end collects the water from the surfaces of perforated pipes, and then, the water is discharged out of the system; the discharged water uniformly flows into the artificial wetland unit of underflow from water inlet square holes through a water distributing tank; and then, after the wastewater flows into a water collecting tank, the wastewater is conveyed to the ecological pond. The system of the invention enables the cumulative mean removing rates of COD, TN, ammonia nitrogen and TP to respectively reach about 55.6%, 84.0%, 76.7% and 84.4%. The system improves the quality of the aquatic environment and the aquatic ecological environment, beautifies the landscape, and has good environmental economic benefit.

Description

technical field [0001] The invention relates to a system and method for removing nitrogen and phosphorus in urban tail water, more specifically an alternate combined wetland system and a method for efficiently removing nitrogen and phosphorus in urban tail water. Background technique [0002] With the active promotion and strengthening of industrial point source and agricultural non-point source pollution control, as well as the acceleration of urbanization, the multiple confluence characteristics of urban tail water (domestic sewage, urban sewage plant tail water, urban runoff and overflow sewage, etc.), The characteristics of high pollution load and high responsibility (conventional nitrogen and phosphorus, heavy metals and organic pollution) have made it the main source of river pollution in the basin. The latest data show that the discharge of waste water in 2008 has more than doubled that in the early 1980s, and more than 80% of these waste waters were directly discharg...

AI Technical Summary

Problems solved by technology

Although most constructed wetlands can achieve the expected removal effect before design, there are still a large number of reports and studies showing that the removal effect of most constructed wetlands is worse than expected, and it is difficult to guarantee the long-term stability of the removal effect

Constructed wetlands are not a good solution to the problem of high concentrations of ammonia nitrogen in the effluent, and the situation becomes worse when the temperature decreases

The reason for this difference is mainly the difference in hydraulic load, filler and technology of the wetland. Many influencing factors make the results and data of the laboratory unable to match the constructed wetland in the field in reality. This undoubtedly affects the design and construction of the constructed wetland. Long-term management poses great difficulties

[0010] (2) The problem of wetland filler blockage

With the operation of constructed wetlands, organic matter will gradually accumulate in the fill and cause fill blockage

According to a survey of more than 100 constructed wetlands in the United States, nearly half of the wetlands became clogged within 5 years of being put into operation, causing surface overflow and reducing treatment efficiency

However, because the clogging mechanism of the wetland bed is too complex and extensive, although many achievements have been made, there are still many problems to be studied

[0011] (3) The process of wetland application is relatively simple

It can be seen from the above invention patents that the current composite constructed wetlands are generally applied in pairs of three types of wetlands: vertical subsurface flow, horizontal subsurface flow, and surface flow. The application objects are water bodies with relatively simple pollution components, and no application has been seen so far. Based on the reports of urban tail water with complex pollution components and high pollution load, the best treatment method for this type of polluted water body is to alternately regulate the aerobic and anaerobic environments in the treatment process (compared with sewage treatment plants). The A / O process adjustment is similar), to achieve the purpose of effectively removing pollutants

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