Table 1.

Heavy metal content of some selected agro-industrial wastes and wastewaters.

	Heavy metal									References
	Cd (ppb)	Cr (ppb)	Co (ppb)	Cu (ppb)	Mn (ppb)	Pb (ppb)	Zn (ppb)	As (ppb)	Ni (ppb)
Poultry manure/litter	0.08–38	5–2403		1.5–487	990	0.7–22	15–1063	0.5–10.4	32.6	(Markou et al., 2015; Zhang et al., 2012)
Swine manure	9			2100	2700	3.6	8800			(Kebede-Westhead et al., 2006)
Cattle manure	<3.6	<3.6		14–113		0.5–5.5	17–377	0.5–19		(Zhang et al., 2012)
Pig manure	0.05–203	1–43		78–1521		1.2–5.1	63–1622			(Zhang et al., 2012)
Olive oil mill wastewater		9		1	1	1	1		12	(Paredes et al., 2005)
Molasses				8.7	11		20	0.24		(Teclu et al., 2009)
Winery wastewater	50–80	200–720	110–300	200–3260	200–1740	550–1340	90–1400		200–650	(Bustamante et al., 2005)
Vinase	20–160	10–950	90–610	50–8570	730–3520	320–1740	410–2670		60–810	(Bustamante et al., 2005)
Digestates (AD)	7.1–19	120–500	16–74	650–1800	140–13,000	70–240	2800–10,000		74–210	(Valeur, 2011)