Mature landfill leachate treatment by coagulation/flocculation combined with Fenton and solar photo-Fenton processes

• Published in: Journal of hazardous materials Vol. 286; pp. 261 - 268
• Main Authors: Amor, Carlos, Torres-Socías, Estefanía De, Peres, José A., Maldonado, Manuel I., Oller, Isabel, Malato, Sixto, Lucas, Marco S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 09.04.2015
• Subjects: Biodegradability; Biological Oxygen Demand Analysis; Coagulation/flocculation; Fenton reagent; Flocculation; Hydrogen Peroxide - chemistry; Iron - chemistry; Landfill leachate; Oxidation-Reduction; Photochemical Processes; Portugal; Solar photo-Fenton; Toxicity; Ultraviolet Rays; Waste Water - chemistry; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - radiation effects; Water Purification - methods; Portugal; Coagulation/flocculation; Biodegradability; Landfill leachate; Toxicity; Fenton reagent; Solar photo-Fenton
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2014.12.036

•Treatment of a mature landfill leachate with a BOD5/COD ratio=0.1.•Combination of coagulation/flocculation and solar photo-Fenton processes.•Coagulation/flocculation with FeCl3·6H2O allow remove 63% COD, 80% turbidity and 74% total polyphenols.•Solar photo-Fenton demonstrates excellent ability to treat the remaining pollutant load of the landfill leachate. This work reports the treatment of a mature landfill leachate through the application of chemical-based treatment processes in order to achieve the discharge legal limits into natural water courses. Firstly, the effect of coagulation/flocculation with different chemicals was studied, evaluating the role of different initial pH and chemicals concentration. Afterwards, the efficiency of two different advanced oxidation processes for leachate remediation was assessed. Fenton and solar photo-Fenton processes were applied alone and in combination with a coagulation/flocculation pre-treatment. This physicochemical conditioning step, with 2gL−1 of FeCl3·6H2O at pH 5, allowed removing 63% of COD, 80% of turbidity and 74% of total polyphenols. Combining the coagulation/flocculation pre-treatment with Fenton reagent, it was possible to reach 89% of COD removal in 96h. Moreover, coagulation/flocculation combined with solar photo-Fenton revealed higher DOC (75%) reductions than single solar photo-Fenton (54%). In the combined treatment (coagulation/flocculation and solar photo-Fenton), it was reached a DOC reduction of 50% after the chemical oxidation, with 110kJL−1 of accumulated UV energy and a H2O2 consumption of 116mM. Toxicity and biodegradability assays were performed to evaluate possible variations along the oxidation processes. After the combined treatment, the leachate under study presented non-toxicity but biodegradability increased.