4. Conclusions
The depuration of a simulated and a real olive mill effluent was
investigated in an electrocoagulation process using a Zn anode.
The treatment of the simulated effluent was strongly affected
by the initial pH, since this parameter determines the quantity of
ions that are released to the liquid medium and the formation of
metal hydroxides necessary to remove pollutants from the system.
In addition, depending on the type of the salt added, the process
efficacy is also greatly affected. In its turn, current density had a
sparingly impact, as well as the type of the cathode used.
Moreover, the effect of the distance between electrodes was quite
negligible and a sequence of fed batch trails involving the electrodes
reutilization showed almost constant activity during the
operation time for four experiments. The operating conditions that
led to the optimum results were: initial pH of the effluent equal to
3.2, current density of 250 A/m2
, space between electrodes equal to
1.0 cm, 1.5 g/L of NaCl and set of Zn anode/SS cathode. According to
these parameters, it was achieved a phenolic content and organic
load removal (measured as COD), around 84.2% and 40.3%, respectively.
Regarding the real effluent filtered without the addition of
NaCl, the treatment attained 72.3% for TPh removal and 20.9% for
COD removal. The depuration system, for both simulated and real
wastewater, allowed the reduction of the initial concentration of
pollutants. However, eco-toxicological tests revealed a still ecological
impact for the treated effluents. The energy consumption
obtained for the treatment of the simulated and the real wastewater
was 40 kW h/m3 and 34 kW h/m3
, respectively.
In short, the electrocoagulation process was optimised.
Although, none of the treatments would allow the wastewater to
be able to be directly discharged into the aquatic medium within
environmental legislation thresholds, this study can support that
the electrocoagulation process may be used as a pre-treatment of
another method, as for instance being previously applied for further
electrochemical oxidation technology. The results attained
for the degradation of the phenolic content of the olive mill
wastewater may be most likely generalised for other agroeffluents.
4. ConclusionsThe depuration of a simulated and a real olive mill effluent wasinvestigated in an electrocoagulation process using a Zn anode.The treatment of the simulated effluent was strongly affectedby the initial pH, since this parameter determines the quantity ofions that are released to the liquid medium and the formation ofmetal hydroxides necessary to remove pollutants from the system.In addition, depending on the type of the salt added, the processefficacy is also greatly affected. In its turn, current density had asparingly impact, as well as the type of the cathode used.Moreover, the effect of the distance between electrodes was quitenegligible and a sequence of fed batch trails involving the electrodesreutilization showed almost constant activity during theoperation time for four experiments. The operating conditions thatled to the optimum results were: initial pH of the effluent equal to3.2, current density of 250 A/m2, space between electrodes equal to1.0 cm, 1.5 g/L of NaCl and set of Zn anode/SS cathode. According tothese parameters, it was achieved a phenolic content and organicload removal (measured as COD), around 84.2% and 40.3%, respectively.Regarding the real effluent filtered without the addition ofNaCl, the treatment attained 72.3% for TPh removal and 20.9% forCOD removal. The depuration system, for both simulated and realwastewater, allowed the reduction of the initial concentration ofpollutants. However, eco-toxicological tests revealed a still ecological
impact for the treated effluents. The energy consumption
obtained for the treatment of the simulated and the real wastewater
was 40 kW h/m3 and 34 kW h/m3
, respectively.
In short, the electrocoagulation process was optimised.
Although, none of the treatments would allow the wastewater to
be able to be directly discharged into the aquatic medium within
environmental legislation thresholds, this study can support that
the electrocoagulation process may be used as a pre-treatment of
another method, as for instance being previously applied for further
electrochemical oxidation technology. The results attained
for the degradation of the phenolic content of the olive mill
wastewater may be most likely generalised for other agroeffluents.
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