Encyclopedia of Environmental Science and Engineering, Volume I and II

742 NATURAL SYSTEMS FOR WASTEWATER TREATMENT

Inf. Effl.

Influent

Effluent

Recycle Recycle

Recycle

Inf.

Eff.

(a) (b)

(c) (d)

FIGURE 3 Alternate flow diagram and configurations of constructed wetlands: (a) Plug flow with recycle; (b) Step feed with recycle;

(c) Step feed in wrap around pond; (d) Peripheral feed with center drawoff.

TABLE 3

Emergent aquatic plants for constructed wetlands

Common name

(Scientific name)

Temperature, °C

Maximum salinity

Survival Desirablea tolerance, pptb Optimum pH

Cattail

(Typha spp.)

10–30 12–24 30 4–10

Common reed

(Phragmites communis)

12–33 10–30 45 2–8

Rush

(Juncus spp.)

16–26 — 20 5–7.5

Bulrush

(Scirpus spp.)

16–27 — 20 4–9

Sedge

(Carex spp.)

14–32 — — 5–7.5

a Temperature range for seed germination: roots and rhizomes can survive in frozen soils.

b ppt  parts per thousands.

Source: Adopted in part from Ref. 15.

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