Loading…
Landfill leachate treatment by solar-driven AOPs
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 2/UV, T...
Saved in:
Published in: | Solar energy 2011-01, Vol.85 (1), p.46-56 |
---|---|
Main Authors: | , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | 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
2/UV, TiO
2/H
2O
2/UV) and homogenous (H
2O
2/UV, Fe
2+/H
2O
2/UV) photocatalytic processes were investigated as an alternative for the treatment of a mature landfill leachate. The addition of H
2O
2 to TiO
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
2O
2/UV and TiO
2/H
2O
2/UV processes, although the H
2O
2 consumption is three times higher in the H
2O
2/UV system. The low efficiency of TiO
2/H
2O
2/UV system is presumably due to the alkaline leachate solution, for which the H
2O
2 becomes highly unstable and self-decomposition of H
2O
2 occurs. The efficiency of the TiO
2/H
2O
2/UV system increased 10 times after a preliminary pH correction to 4. The photo-Fenton process is much more efficient than heterogeneous (TiO
2, TiO
2/H
2O
2/UV) or homogeneous (H
2O
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
2/H
2O
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
2+
L
−1, which is in agreement with path length of 5
cm in the photoreactor. The kinetic behaviour of the process (60
mg Fe
2+ L
−1) comprises a slow initial reaction, followed by a first-order kinetics (
k
=
0.020
L
kJ
UV
-
1
,
r
0
=
12.5
mg
kJ
UV
-
1
), with H
2O
2 consumption rate of
k
H2O2
=
3.0
mmol H
2O
2
kJ
UV
-
1
, and finally, the third reaction period, characterized by a lower DOC degradation and H
2O
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
2O
2 was consumed for achieving 86% mineralization (DOC
final
=
134
mg
L
−1) and 94% aromatic content reduction after 110
kJ
UV L
−1, using an initial iron concentration of 60
mg Fe
2+ L
−1. |
---|---|
ISSN: | 0038-092X 1471-1257 |
DOI: | 10.1016/j.solener.2010.11.001 |