Reactors for Water Treatment

Photocatalytic reactors for water treatment can be classified according to their design characteristics. 

In slurry reactors, the catalyst particles are freely dispersed in the fluid phase (water) and consequently, the photocatalyst is fully integrated in the liquid mobile phase. The immobilized catalyst reactor design features a catalyst anchored to a fixed support, dispersed on the stationary phase (the catalyst-support system). 

Two subcategories branch off from solar illuminated reactors nonconcentrating reactors and concentrating reactors. Non-concentrating solar irradiated reactors employ intensities equal or lesser than natural solar irradiation while concentrating solar reactors use irradiation intensities that surpass irradiations equivalent to one sun. 

In immersed soui ce reactors, the lamp is placed inside the unit. External source photocatalytic reactors have lamps located outside the reactor vessel. In distributed reactors, irradiation is transported from the source to the reactor by optical means such as reflectors or light guides. 

The majority of the photocatalytic reactors cuiTently in use for water treatments are of the well-mixed slun-y variety (Augugliaro et al., 1990 Pichat, 1988). Slun-y systems have shown the lai gest photocatalytic activity when compared to photocatalytic reactors with immobilized photocatalyst (Matthews and McEvoy, 1992 Pai ent et al., 1996 Pozzo et al., 1999 Wyness et al., 1994b). 

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Destaillats H, Lesko TM, Knowlton M, Wallace H, Hoffmann MR. Scale-up of sonochemical reactors for water treatment. Ind Eng Chem Res 2001 40 3855-3860. 

Mukherjee PS, Ray AK (1999) Major Challenges in the Design of a Large-Scale Photocatalytic Reactor for Water Treatment, Chem. Eng. Technol. 22, No. 3 253-260. 

A. K. Ray, Design, modeling and experimentation of a new large-scale photocatalytic reactor for water treatment, Chem. Eng. Sci. 54, 3113-3125 (1999). 

Three photocatalytic reactors for water treatment and one for air treatment have been conceptualized ... 

Miguel Salaices-Arredondo is a PhD graduate from the University of Western Ontario in Canada. Since 1990, Dr. Salaices has worked as a reseai ch engineer in the Nuclear Energy Department of the Institute de Investigaciones Electricas in Mexico. His reseai ch interests include the development of reactors for water treatment with a focus on the optimization and the modeling of radiation distribution in photocatalyst suspended media. Dr. Salaices is also involved in the development of computational systems for the... 

Mamane H, Colorni A, Bar I, Ori I, Mozes N (2010) The use of an open channel, low pressure UV reactor for water treatment in low head recirculating aquaculture systems (LH-RAS). Aquae Eng 42(3) 103-111... 

Cravotto G, Di Carlo S, Curini M, Tumiatti V, Rogerro C (2007) A new flow reactor for the treatment of polluted water with microwave and ultrasound. J Chem Tech Biotech... 

Regarding air treatment, to our knowledge, large-scale photocatalytic reactors based on fluidized beds are not used Ti02 is always supported. For water treatment, the system designed by Purifies Environment Tech-... 

Yue PL. Oxidation reactors for water and wastewater treatment. Water Sci Technol 1997 35 189-196. 

Figure 21 Scheme of the pilot flow reactor for the treatment of 10-75 L of waste-waters by the Electro-Fenton and Peroxi-coagulation processes. (From Ref. 143.)... 

Photo-initiated AOPs are subdivided into VUV and UV oxidation that are operated in a homogeneous phase, and in photocatalysis (Fig. 5-15). The latter can be conducted in a homogeneous aqueous phase (photo-enhanced Fenton reaction) or in a heterogeneous aqueous or gaseous phase (titanium dioxide and certain other metal oxide catalysts). These techniques apply UV-A lamps or solar UV/VIS radiation and they are in pre-pilot or pilot status. According to Mukhetjee and Ray (1999) the development of a viable and practical reactor system for water treatment with heterogeneous photocatalysis on industrial scales has not yet been successfully achieved. This is mainly related to difficulties with the efficient distribution of electromagnetic radiation (UV/VIS) to the phase of the nominal catalyst. 

O. M. Alfano, M. Vicente, S. Esplugas, and A. E. Cassano, Radiation field inside a tubular multilamp reactor for water and wastewater treatment, Ind. Eng. Chem. Res. 29, 1270-1278 (1990). 

G. Kreysa, Reactor design for electrochemical water treatment in Process Technologies for Water Treatment (Ed. S. Stucki), Plenum Publishing Corporation, New York, 1988. 

Fig. 3.60. E quipment for water treatment by a double-stage precipitation with lime, soda and phosphates. 1 — raw water supply, 2 — reactor for the precipitation with lime and soda, 3,5 — sludge discharge, 4 — reactor for the phosphate precipitation, 6 — high-rate filter, 7 — discharge of treated water...

Kreysa G. (1988) Reactor design for electrochemical water treatment. In Process Technology for Water Treatment (Edited by Stucki S.), pp. 65-83. Plenum Press, New York. 

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