Table 6: Digestate heavy metals concentration in mL/g at the end of the experiment (after six HRT cycle of 20 days).

Parameter1% PF2% PF5% FW1% GT2% GT100% SSLimit (mg/kg)

Ca
Mg
Ca hardness
Mg hardness
Al
As<1<1<1<1<1<120
Cd<0.1<0.1<0.1<0.1<0.1<0.11
Cr400
Cu100
Fe
Pb<0.5<0.5<0.5<0.5300
Hg<1<1<1<1<1<11
Ni60
Zn200
Si
Si-SiO2
S
S-SO4

Heavy metal screening of the digestate samples was carried out by a commercial laboratory (ALS Environmental Division: Water Research Group).
Contaminant upper limits for biosolids as grade C1 [30].