Nitrogen Removal

Although the SSF system at Santee, California, was able to remove 86% of the nitrogen from primary effluent, other SSF systems have reported removals of from 20 to 70%. When detention times exceed 6 to 7 d, an effluent total nitrogen concentration of about 10 mg/L can be expected, assuming a 20- to 25-mg/L influent nitrogen concentration. If the applied wastewater has been nitrified (using extended aeration, overland flow, or recirculating sand filters), the removal of nitrate through denitrification can be accomplished with detention times of 2 to 4 d.

TABLE 7.4

Removal for Metals through Subsurface Flow Constructed Wetlands at Hardin, Kentucky

TABLE 7.4

Removal for Metals through Subsurface Flow Constructed Wetlands at Hardin, Kentucky

Influent

Influent

Effluent

Effluent

Range

Average

Range

Average

Removal

Metal

(MS/L)

(Mg/U

(Mg/L)

(Mg/L)

(%)

Aluminum

380-3800

1696

<50-100

<50

>9l

Copper

20-190

ll

<10

<10

>8l

Iron

310-2400

1111

3l0-2900

1234

-10

Manganese

44-480

258

64-590

288

-10

Zinc

20-120

64

<10

<10

>84

Source: Hines, M., Southeast Environmental Engineering, Concord, Tennessee (personal communication).

Source: Hines, M., Southeast Environmental Engineering, Concord, Tennessee (personal communication).

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