Solar oxidation assisted removal of arsenic (SORAS) in photo-tubular reactors of semi-circular section - kinetics of Fe(OH)3 flock growth
The growth kinetics of Fe(OH)3 flocs formed in the Solar Oxidation Assisted Arsenic Removal (SORAS) process in tubular photo-reactors of semi-circular section applied to the treatment of groundwater naturally contaminated with arsenic were studied. Four photo-reactors of various diameters were used that provide concentration capabilities of the solar UV intensity between 2.8 to 10 times the incident intensity. Solar concentrators were built by recycling waste materials: glass tubes from Ne lamps, 6” sanitary sewer pipes (PVC) and commercial tin sheets, coated by aluminium sheets.
The most important results of the study are:
- The empirical relationship between the growth rates of flocs up to 0.5 mm and the intensities of effective UVA radiation is linear (r = 0.990), in the experimental range studied. This means that the generation of free radicals in the solution, driven by the number of photons of UVA fingerboard, is still the limiting stage of the global Fe(OH)3 precipitate formation process.
- Calculations of treatment capacity, in continuous regime (considering hydraulic residence times equal to the irradiation times), showed the largest photo-reactor capacity of 71 cm in diameter (the largest diameter), achieving a daily flow of 190 Lm-2, for an operation of 5 h per day. From a constructive and economic point of view, this photo-reactor is more practical than smaller diameter reactors, due to the smaller number of accessories and materials involved.
Project Leader:
Ramiro Escalera Vásquez PhD.
Email: rescalera@upb.edu
Researchers:
Omar Ormachea Muñoz PhD.
Nicolás Casanovas Otero
Published in: Investigación & Desarrollo, No 11, pp. 37 - 45, 2011
