Table 6.

Effect of tannin on heavy metal removal (tannin dosage 0.73 g, pH 6, 250 rpm for15 min, 60 rpm for 30 min and 30 min of settling).

Heavy Metals	Initial Concentration in Leachate	Residual After Tannin Coagulation	Removal (%)
Fe (mg/L)	0.8 ± 0.2	0.1 ± 0.0	89 ± 2
Zn (µg/L)	280 ± 2	15 ± 1	94 ± 3
Cu (µg/L)	42 ± 4	2.5 ± 0.3	94 ± 2
Cr (µg/L)	45 ± 2	5 ± 1	90 ± 1
Cd (µg/L)	0.6 ± 0.1	0.5 ± 0.1	17 ± 1
Pb (µg/L)	4 ± 1	0.3 ± 0.0	94 ± 2
As (µg/L)	17 ± 7	2.4 ± 1	86 ± 1
Co (µg/L)	11 ± 8	1.7 ± 0.5	84 ± 2