**4.3 Effect of the mixture: Alginate + FeCl3**

#### *4.3.1 Alginate alone*

The study of the elimination of the pollution of leachate by coagulation flocculation by the alginate alone is given in **Figure 14**. The results obtained showed that the optimal dose of alginate for the elimination of COD and the turbidity are respectively 60 and 75% with an optimal dose of 120 mg/l of alginate, while producing a small quantity of sludge (20 ml/l).

The effect of pH on alginate flocculation coagulation (**Figure 15**), showed that the latter has little effect on the removal of COD and turbidity. For a pH between

**Figure 14.** *Effect of alginate alone on COD removal and turbidity Turb = 125 NTU.*

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

#### **Figure 15.**

*Effect of pH on the reduction of turbidity and COD by alginate (120 mg/l).*

1 and 10, no sludge production was observed for Alginate concentrations below 800 mg/l, while the volume of sludge increases from pH 10.

Furthermore, the study of the elimination of pollution from leachate discharges by the mixture of FeCl3 and alginate is given in **Figure 16** (fixed alginate: 120 mg/l and variable FeCl3).

The results obtained showed that the mixture of FeCl3 and Alginate has an optimal concentration of around 120 mg/l of Alginate and a variable concentration of FeCl3 increases the COD from 2900 to 1100 mg/l with a yield 60% COD 65% turbidity. The COD value decreases with the increase in the FeCl3 concentration. As for the variation in turbidity, this remains negligible (30 NTU) from a concentration of 120 mg/l of alginate. The amount of sludge formed increases with an increase in alginate. The optimal concentrations for the removal of COD and turbidity by Alginate vary around 20 mg/l with a FeCl3 concentration of 2500 mg/l at pH 6.5.

**Figure 16.** *Study of the mixture: Alginate (120 mg/l) + variable FeCl3.*

**Figure 17.** *Study of the mixture FeCl3 (2500 mg/l) + alginate.*

**Figure 18.** *Variation of turbidity (a) and COD (b) during coagulation flocculation by flocculants supplied by an Italian company.*

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

Furthermore, **Figure 17** illustrates the effect of Alginate on flocculation coagulation while keeping a fixed concentration of FeCl3 (2500 mg/l).

The results showed that the Alginate and FeCl3 mixture has an optimal concentration of around 2500 mg/l, which resulted in very high COD removal with a 50% removal efficiency. The COD value increases with that of the Alginate The turbidity which varies around 30 NTU and remains constant from 50 mg/l of Alginate, while the volume of sludge produced increases with the increase of the Alginate stabilizes around 125 ml/l. The optimum concentration of Alginate is 120 mg/l. COD and turbidity values for optimum FeCl3 and Alginate values show values of 1360 mg/l and 30 NTU, respectively.

#### **4.4 Effect of flocculants chemec 1, 2 and 3 supplied by an Italian company**

We carried out a comparative study on the elimination of pollution from leachate using three flocculant (Chimec 1, 2 and 3) supplied by an Italian company. The results (**Figure 18a**) showed that the turbidity decreases from 190 to 40 NTU for Chimec 1,2, for an optimal concentration of 4 mg/l then increases to 100 NTU for 30 mg/l of Chimec1 and 2. As regards the flocculant Chemic 3, the results showed a final elimination of the turbidity which is around 60 NTU for the same optimal concentration (4 mg/l) while the turbidity remains stable for Chimec 3 for a concentration of 10 mg/l.

As for the COD content (**Figure 18b**) during the treatment with the three flocculants, the results showed a decrease up to 1500 mg/l for 4 mg/l of flocculant, with an elimination efficiency of 40%, then increased for Chimec 1 and 2 arriving at around 2000 mg/l for 30 mg/l of flocculant. The COD remains almost stable for Chimec3 from 4 mg/l. In fact, no significant difference was observed as regards the elimination of COD by the three flocculants while producing a small amount of sludge in the case of the three flocculants.
