A combined constructed wetland system and method for treating low-concentration heavy metal sewage

Abstract

The invention discloses a combined constructed wetland system. The combined constructed wetland system successively comprises a water adjusting and distribution tank, vertical flow constructed wetlands, a horizontal flow constructed wetland and a surface flow constructed wetland, wherein two groups of vertical flow constructed wetlands are provided and are alternatively operated. The invention also discloses a method for treating the low-concentration heavy metal sewage by utilizing the combined constructed wetland system. By adopting the combined constructed wetland system, the conventional pollutants and heavy metals can be synergistically removed, the treatment effect is stable and efficient, the removal rate of COD, ammonium nitrogen, total nitrogen, total phosphorus, hexavalent chromium and total nickel can respectively reach 60 percent, 80 percent, 70 percent, 65 percent, 50 percent and 50 percent or more, CODCr is less than or equal to 20 mg / L, NH3-N is less than or equal to 1.0mg / L, TN is less than or equal to 1.0 mg / L, TP is less than or equal to 0.2 mg / L, the hexavalent chromium is less than or equal to 0.05 mg / L, and the total nickel is less than or equal to 0.02 mg / L.The operation cost is less than 0.2 Yuan per ton. The combined constructed wetland system is flexible in operation, convenient in management, free from secondary pollution and significant in environmental benefit and social benefit.

Description

technical field [0001] The invention belongs to the field of sewage treatment, and relates to a combined constructed wetland system and a method for treating low-concentration heavy metal sewage, in particular to a method for using a combined constructed wetland to treat tail water from a sewage station in an electroplating concentration area, which can efficiently reduce nitrogen and phosphorus in the tail water The low concentration of pollutants such as organic matter and heavy metals enables it to meet the Class III water standard of the "Surface Water Environmental Quality Standard" (GB3838-2002), especially suitable for industrial concentration areas with serious heavy metal pollution. Background technique [0002] The development of the industrial industry has promoted the rapid rise of my country's economic situation and also brought serious pollution problems. With the continuous increase of industrial sewage discharge, many cities in my country have serious water po...

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Problems solved by technology

[0004] Purpose of the invention: In order to solve the problem of synergistic and efficient removal of nitrogen, phosphorus and heavy metal pollutants in the tail water of the sewage treatment station in the electroplating concentration area, realize the standard treatment from Table 3 of the "Electroplating Pollutant Discharge Standard" (GB21900-2008) to the "Surface Water Environmental Quality Standard" (GB3838-2002) Class III Water Standard

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