The report presents the results of selected heavy metals (Zn, Cu, Cd, Ni, Pb) removal from industrial wastewater sludge collected from metallurgy industry. As washing solutions two chelating agents were used: EDTA and citric acid. The study was focused on 0.000 (deionized water), 0.010, 0.050, 0.075, 0.100 M and 0.000, 0.050, 0.100, 0.500, 1.000 M, EDTA and citric acid solutions, respectively.
Efficiency of EDTA and citric acid solutions for metal removal was studied by extraction of sludge samples with chelators. Chemical extraction of selected metals was effective for both types of solution. Optimal concentration of EDTA was 0.100M for Zn, Ni and Cd, 0.075 M for Cu and Pb. Optimal concentration of citric acid was 0.500 M for all analyzed metals
The possibility of Cu(II), Ni(II) and Sn(II) removal from model solutions and real wastewater from
the production of PCBs using Na2
CS3
for precipitation was presented in this paper. The testing was carried out
on a laboratory scale using model and real industrial wastewater containing additives in the form of complexing
compounds used in the production of PCBs (Na2
EDTA, NH3(aq), thiourea) and recommended by the USEPA
(Na3
MGDA, Na4
GLDA). Application of Na2
CS3
in optimal conditions of conducting precipitation process was
connected with obtaining wastewater containing low concentrations of metals (Cu 0.02 mg/L, Sn <0.01 mg/L, Ni
<0.005 mg/L at pH 9.39 and Cu 0.07 mg/L, Sn <0.01 mg/L, Ni 0.006 mg/L at pH 7.79). Controlled application of
Na2
CS3
by the use of a platinum redox electrode was also connected with obtaining treated wastewater containing
low concentrations of metals (Cu 0.019 mg/L, Sn <0.05 mg/L, Ni <0.0098 mg/L at pH 9–9.5 and E= -142 mV in the
laboratory scale and Cu 0.058 mg/L, Sn <0.005 mg/L, Ni 0.011 mg/L at pH 9.14 and E= +10 mV in the industrial
scale). Changing the value of redox potential of treated wastewater by dosing Na2
CS3
made it possible to control
the precipitation process on laboratory and industrial scale by the use of a platinum redox electrode. Controlled
application of Na2
CS3
can be used to remove Cu(II), Ni(II) and Sn(II) from industrial effl uent containing chelating
compounds like Na2
EDTA, NH3(aq), thiourea, Na3
MGDA and Na4
GLDA.