Table 2.

The sum of water-soluble, carbonate-bound, and Fe-Mn oxide-bound fractions of heavy metal in solid phase after anaerobic digestion

nZVI-BC	Cr (mg/kg)	Ni (mg/kg)	Cd (mg/kg)	Cu (mg/kg)	Zn (mg/kg)
Control	35.35 ± 1.2a	40.59 ± 1.1b	0.38 ± 0.01	38.87 ± 1.28	366.37 ± 11.2
0.75 g	28.25 ± 1.0	37.76 ± 1.2	0.32 ± 0.01	31.94 ± 1.21	339.59 ± 11.29
1.50 g	22.96 ± 0.92	31.75 ± 0.96	0.25 ± 0.01	24.52 ± 0.79	244.49 ± 11.72
2.50 g	16.23 ± 0.76	27.46 ± 0.69	0.20 ± 0.01	20.04 ± 0.89	234.88 ± 9.02
4.00 g	23.16 ± 0.95	30.43 ± 1.19	0.27 ± 0.01	29.19 ± 1.23	207.50 ± 8.71
5.00 g	21.17 ± 0.91	27.51 ± 0.79	0.28 ± 0.01	25.14 ± 0.72	193.60 ± 7.79

^aValues represent the means ± standard deviation (SD)

^bThe date are expressed as the mean value ± standard deviation (n = 3)