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Table 2

Mean (n = 80 per sampling site) water quality of the effluent from wetland cells CW1, 2, 3, 4 at Formosa Steel work, Vietnam, for the period September 2017 to July 2018. Arithmetic mean ± SD (min-max) are shown and units are as in Table 1

Variables measured	Wetland cells
Variables measured	CW1	CW2	CW3	CW4
Color	20.6 ± 4.5 (18–30)	19.6 ± 2.8 (17–28)	17.9 ± 2.9 (14–25)	16.7 ± 2.6 (12–21)
COD	20.2 ± 2.9 (15–29)	19.9 ± 2.0 (14–25)	17.4 ± 3.0 (11–23)	16.7 ± 3.3 (10–24)
BOD₅	7.7 ± 1.6 (6.0–11)	7.8 ± 1.1 (5.6–10.1)	6.7 ± 2.0 (4.9–9.1)	6.5 ± 0.9 (4.2–9.3)
TSS	15 ± 1.5 (10–22)	14.4 ± 2.5 (8–20)	13.0 ± 2.5 (5–17)	13.4 ± 2.4 (7–18)
Mn	0.27 ± 0.06 (0.22–0.61)	0.22 ± 0.05 (0.1–0.32)	0.17 ± 0.06 (0.03–0.41)	0.16 ± 0.08 (0.03–0.55)
Fe	0.22 ± 0.03 (0.06–0.49)	0.25 ± 0.16 (0.04–0.56)	0.18 ± 0.09 (0.03–0.71)	0.17 ± 0.10 (0.02–0.7)
TN	9.2 ± 1.5 (9.2–17)	9.5 ± 2.4 (8.3–16)	9.2 ± 2.1 (6.5–14.9)	8.9 ± 2.0 (6.1–15.8)
NH₄⁺-N	0.29 ± 0.08 (0.13–0.67)	0.15 ± 0.03 (0.09–0.42)	0.08 ± 0.02 (0.02–0.69)	0.04 ± 0.01 (0.01–0.14)

Variables measured	Wetland cells
Variables measured	CW1	CW2	CW3	CW4
Color	20.6 ± 4.5 (18–30)	19.6 ± 2.8 (17–28)	17.9 ± 2.9 (14–25)	16.7 ± 2.6 (12–21)
COD	20.2 ± 2.9 (15–29)	19.9 ± 2.0 (14–25)	17.4 ± 3.0 (11–23)	16.7 ± 3.3 (10–24)
BOD₅	7.7 ± 1.6 (6.0–11)	7.8 ± 1.1 (5.6–10.1)	6.7 ± 2.0 (4.9–9.1)	6.5 ± 0.9 (4.2–9.3)
TSS	15 ± 1.5 (10–22)	14.4 ± 2.5 (8–20)	13.0 ± 2.5 (5–17)	13.4 ± 2.4 (7–18)
Mn	0.27 ± 0.06 (0.22–0.61)	0.22 ± 0.05 (0.1–0.32)	0.17 ± 0.06 (0.03–0.41)	0.16 ± 0.08 (0.03–0.55)
Fe	0.22 ± 0.03 (0.06–0.49)	0.25 ± 0.16 (0.04–0.56)	0.18 ± 0.09 (0.03–0.71)	0.17 ± 0.10 (0.02–0.7)
TN	9.2 ± 1.5 (9.2–17)	9.5 ± 2.4 (8.3–16)	9.2 ± 2.1 (6.5–14.9)	8.9 ± 2.0 (6.1–15.8)
NH₄⁺-N	0.29 ± 0.08 (0.13–0.67)	0.15 ± 0.03 (0.09–0.42)	0.08 ± 0.02 (0.02–0.69)	0.04 ± 0.01 (0.01–0.14)