**4. Combined technologies for landfill leachate treatment**

Since the characteristics of landfill leachate is varying and the nature is recalcitrant, therefore no single technology is said to be sufficient for the overall treatment. To overcome this issue the technologies are applied as an integrated system in which various physicochemical and biological techniques with their different combinations are implemented for the removal of pollutants from landfill leachate. **Table 5** consists of some of the combined technologies used in the treatment of landfill leachate.

Claudia et al. [76] coupled the processes of photo electrooxidation (PEO) and activated carbon (AC) to treat highly concentrated stabilized leachate from a landfill and obtained the removal of 67.2%, 58.3% and 48.4% for COD, ammoniacal nitrogen and total Kjeldahl nitrogen respectively.

Mojiri et al. [77] performed the treatment of landfill leachate using the application of dual techniques by using electro-ozonation followed by sequencing batch reactor (SBR) process augmented with a composite adsorbent (P-BAZLSC) and obtained high efficiency in the removal of COD, color and nickel. In the electro-ozonation treatment the optimum ozone dosage and reaction time were kept as 120 mg/l and 96.9 min, respectively. The removal obtained was 64.8%, 90.4%, and 52.9% for COD, color and nickel, respectively. Sequentially the leachate was transferred to PB-SBR system. PB-SBR improvised the removal efficiencies from 64.8% to 88.2%, from 90.4% to 96.1%, and from 52.9% to 73.4% for COD, color, and nickel respectively.

The anaerobic treatment of landfill leachate having high concentration of (341.6 ± 21.3 mg/L) was combined by coagulation flocculation (CF) process in which the coagulant and flocculant used are ferric chloride and cationic polymer respectively. The removal efficiencies obtained at an optimum dose of 4.4 g/L of coagulant and 9.9 ml/L of flocculants: 80 ± 8.7, 69 ± 4.8, 94 ± 1.3 and 89 ± 6% for COD, turbidity, color and phenolic compounds respectively [78].

The treatment of landfill leachate was investigated using electrocoagulation process, the anode and cathode in the electrocoagulation system was both of iron. The conditions which were optimized to get the desired results were pH: 7.73, interelectrode distance: 1.16 cm, and electrolyte concentration (NaCl): 2.00 g/l (key factors playing significant role). The process obtained the removal efficiency for


#### **Table 5.**

*Combined technologies for landfill leachate treatment.*

*Effectiveness of Anaerobic Technologies in the Treatment of Landfill Leachate DOI: http://dx.doi.org/10.5772/intechopen.94741*

COD and color as 45.1% and 82.7% respectively [79]. A two-stage anoxic/oxic (A/O) combined membrane bioreactor (MBR) developed by Liu et al. [80], was operated for 113 days to treat landfill leachate. The removal for different parameters obtained were COD = 80.6%, ammonia (NH4 + -N) = 99.04% and total nitrogen (TN) = 74.87%.

Hua et al. [81] developed an up flow anaerobic sludge semi-fixed filter for the treatment of landfill leachate by using soft polyurethane belt packing as the supporting carrier. The removal of COD increased with the gradual increase of OLR while the removal of sulphate decreased. However, the study showed that when the reactor was operated at the designed value of 9 kgCOD/m3 /d the removal of sulphate and COD were found to be 90 and 81% respectively. The results indicate that the semi fixed carrier can form an effective biofilm and the UASSF system can work efficiently in the treatment of landfill leachate.

### **5. Conclusion**

Municipal solid waste disposal is a critical global issue which needs to be addressed to check the environmental hazards associated with improper disposal. Sanitary landfilling is the widely adopted method of disposal throughout the globe, but it is linked with the severe consequences of the generation of landfill leachate, which should be treated before disposal because of its toxic and recalcitrant nature. The chapter provides the brief overview of the landfills, landfill leachate and different treatment technologies suggested by the previous studies. Extensive details are incorporated about the anaerobic technologies treating landfill leachate followed by the hybrid or combined technologies. Hopefully, the chapter will give an understanding about different anaerobic bioreactors efficiently treating the landfill leachate.

### **Acknowledgements**

The authors are thankful to Malaysia-Japan International Institute of technology (MJIIT) for providing the support to conduct the study and also grateful to the staff of Jeram sanitary landfill for providing the access into the Jeram Sanitary landfill to understand the basic components and treatment processes.
