**4.2 Effect of the mixture: Flocculant Lesieur + FeCl3**

To get an idea of the effectiveness of the leachate treatment by another flocculant used by the company Lesieur in Casablanca for the depollution of wastewater by SBR (sequential batch reactor), we carried out coagulantion flocculation tests by the flocculant alone or mixed with FeCl3. The effect of the Lesieur flocculant on the removal of turbidity and COD is illustrated in **Figure 10**. The results showed that the COD and turbidity parameters decrease with increasing concentration of Lesieur flocculant. The optimum concentration of the flocculant varies around 200 mg/l (**Figure 10**). From this value the COD concentration increases with the increase in the flocculant concentration. The results showed that the COD goes from 3300 to 1300 mg/l and the turbidity goes from 140 to 35 NTU (optimal value) with a removal efficiency of 39% and 75% respectively for the COD and the turbidity.

To compare the effect of pH on Astral flocculant versus Lesieur flocculant, we studied the effect of pH on coagulation flocculation by Lesieur flocculant. The results are shown in **Figure 11**. The effect of pH on the elimination of pollution from leachate discharges by coagulation flocculation has shown that the optimum

#### **Figure 10.**

*Reduction of turbidity and COD by Lesieur Flocculant alone COD = 3300 mg/l, Turb = 130 NTU.*

#### **Figure 11.**

*Effect of pH on the reduction of turbidity and COD by Lesieur Flocculant (200 mg/l) COD = 3300 mg/l, Turb = 115 NTU.*

*Reducing Pollution of Stabilized Landfill Leachate by Mixing of Coagulants and Flocculants… DOI: http://dx.doi.org/10.5772/intechopen.97253*

**Figure 12.**

*Study of the mixture: FeCl3 + Flocculant Lesieur (200 mg/l flocculant) variable FeCl3. COD = 3200 mg/l, Turb = 130 NTU to be reviewed.*

**Figure 13.** *Study of the mixture: FeCl3 (2500 mg/l) + Lesieur Flocculant. Turb = 125 NTU.*

pH varies around 6. In addition, the turbidity of raw leachate increases from 115 NTU to 30 NTU while the COD drops from 3300 mg/l to 1550 mg/l for the optimal concentration of 200 mg/l of the flocculant with a yield of 74% and 54% respectively for turbidity and COD.

FeCl3 as a coagulant alone or as a mixture with other flocculants remains the most appreciated for better elimination of pollution from leachate discharges [34] in the form of COD and turbidity. We therefore studied the effect of FeCl3 (200 mg/l of the flocculant, pH = 6) on the Lesieur flocculant.

**Figure 12** shows that the mixture (FeCl3 + Flocculant Lesieur) made it possible to reduce pollution, with a reduction in COD from 3200 mg/l (crude) to 800 mg/l for an optimal concentration of 200 mg/l of flocculant of Lesieur and 3000 mg/l of FeCl3 while the turbidity has a minimum value for a concentration of 100 mg/l of FeCl3. The volume of the settled sludge increases to reach a maximum of 200 ml/l for the concentration of 3000 mg/l of FeCl3 as the optimum value (**Figure 12**).

To get an idea of the efficiency of the leachate treatment with the cationic flocculant used at the Lesieur company wastewater treatment plant in Casablanca, we studied the flocculation coagulation of leachate discharges by fixing the FeCl3 concentration while at the same time varying that of the lesieur cationic flocculant. The results are illustrated in **Figure 13**. These results showed that the mixture made it possible to reduce the pollution, with a decrease in the COD from 3200 mg/l (crude) to 1500 mg/l (200 mg/l of Lesieur flocculant). The volume of the settled sludge increases to reach a maximum of 220 ml/l. Certainly, it can be concluded that the optimal dose of the cationic flocculant in the mixture (FeCl3 + Lesieur flocculant) (FeCl3 2500 mg/pH 6) is 20 mg/l for the lesieur flocculant.
