Landfill leachate treatment by solar-driven AOPs

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Solar Energy

DOI:https://doi.org/10.1016/J.SOLENER.2010.11.001· OSTI ID:21401370

Rocha, Elisangela M.R. ^[1]; Vilar, Vitor J.P.; Boaventura, Rui A.R. ^[2]; Fonseca, Amelia; Saraiva, Isabel ^[3]

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1. Universidade Federal do Ceara, Campus do Pici, Centro de Tecnologia, Departamento de Engenharia Hidraulica e Ambiental, Laboratorio de Saneamento (LABOSAN), Avenida da Universidade, 2853 - Benfica, 60020-181 Fortaleza (Brazil)
2. LSRE - Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)
3. Efacec Ambiente, SA, Rua Eng. Frederico Ulrich - Guardeiras, Apartado 3003, 4471-907 Moreira da Maia (Portugal)

Sanitary landfill leachate resulting from the rainwater percolation through the landfill layers and waste material decomposition is a complex mixture of high-strength organic and inorganic compounds which constitutes serious environmental problems. In this study, different heterogeneous (TiO{sub 2}/UV, TiO{sub 2}/H{sub 2}O{sub 2}/UV) and homogenous (H{sub 2}O{sub 2}/UV, Fe{sup 2+}/H{sub 2}O{sub 2}/UV) photocatalytic processes were investigated as an alternative for the treatment of a mature landfill leachate. The addition of H{sub 2}O{sub 2} to TiO{sub 2}/UV system increased the reduction of the aromatic compounds from 15% to 61%, although mineralization was almost the same. The DOC and aromatic content abatement is similar for the H{sub 2}O{sub 2}/UV and TiO{sub 2}/H{sub 2}O{sub 2}/UV processes, although the H{sub 2}O{sub 2} consumption is three times higher in the H{sub 2}O{sub 2}/UV system. The low efficiency of TiO{sub 2}/H{sub 2}O{sub 2}/UV system is presumably due to the alkaline leachate solution, for which the H{sub 2}O{sub 2} becomes highly unstable and self-decomposition of H{sub 2}O{sub 2} occurs. The efficiency of the TiO{sub 2}/H{sub 2}O{sub 2}/UV system increased 10 times after a preliminary pH correction to 4. The photo-Fenton process is much more efficient than heterogeneous (TiO{sub 2}, TiO{sub 2}/H{sub 2}O{sub 2}/UV) or homogeneous (H{sub 2}O{sub 2}/UV) photocatalysis, showing an initial reaction rate more than 20 times higher, and leading to almost complete mineralization of the wastewater. However, when compared with TiO{sub 2}/H{sub 2}O{sub 2}/UV with acidification, the photo-Fenton reaction is only two times faster. The optimal initial iron dose for the photo-Fenton treatment of the leachate is 60 mg Fe{sup 2+} L{sup -1}, which is in agreement with path length of 5 cm in the photoreactor. The kinetic behaviour of the process (60 mg Fe{sup 2+} L{sup -1}) comprises a slow initial reaction, followed by a first-order kinetics (k = 0.020 LkJ{sub UV}{sup -1}, r{sub 0} = 12.5 mg kJ{sub UV}{sup -1}), with H{sub 2}O{sub 2} consumption rate of k{sub H2O2} = 3.0 mmol H{sub 2}O{sub 2}kJ{sub UV}{sup -1}, and finally, the third reaction period, characterized by a lower DOC degradation and H{sub 2}O{sub 2} consumption until the end of the experiment, presumably due to the formation of low-molecular-weight carboxylic groups. A total of 306 mM of H{sub 2}O{sub 2} was consumed for achieving 86% mineralization (DOC{sub final} = 134 mg L{sup -1}) and 94% aromatic content reduction after 110 kJ{sub UV} L{sup -1}, using an initial iron concentration of 60 mg Fe{sup 2+} L{sup -1}. (author)

• OSTI ID: 21401370
• Journal Information: Solar Energy, Vol. 85, Issue 1; Other Information: Elsevier Ltd. All rights reserved; ISSN 0038-092X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
HYDROGEN PEROXIDE
SANITARY LANDFILLS
TITANIUM OXIDES
IRON IONS
IRON
SOLUTIONS
WASTE WATER
CHEMICAL REACTION KINETICS
PHOTOCATALYSIS
REDUCTION
MINERALIZATION
AROMATICS
EFFICIENCY
CONSUMPTION RATES
ULTRAVIOLET RADIATION
PH VALUE
ACIDIFICATION
DOSES
LEACHATES
Solar-driven AOPs