Water disinfection by solar energy

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ABSTRACT This work was conducted to investigate the effect of augmentation of incident solar radiation (UV portion of the spectrum) on speeding up of the disinfection of contaminated water. The experiments were conducted using three treatment units, the first unit is a base unit, which is simply a transparent bottle contains the contaminated water; the second unit is the same as the base one, but flat mirror (FM) is located below this unit to reflect solar radiation back to the unit. A concave mirror (CM) is used with the third unit to concentrate the reflected solar radiation onto the unit. Both mirrors were used to reflect and redirect the incident UV radiation onto the units and hence the incident UV is augmented. The efficiency of each unit was indicated by its potential to decrease the amounts of Total coliform, E. coli and P. aeruginosa, all of which were measured using the IDEXX unit. The measurements of these contaminates were conducted on an hourly basis. The contaminated water was taken from a sewage treatment unit located at AL-Zaytoonah University of Jordan in Amman. It was found that the disinfection unit with the FM was the most efficient one in water disinfection, such that after 150 min of exposure time of the unit to solar radiation the counts of total coliform, E. coli and Aeruginosa were reduced by 96.8%, 99.6%, 96%, respectively. This was followed by the CM fitted unit, such that and after 150 min of exposure time, the total counts of total coliform, E. coli, and Aeruginosa were reduced by 96%, 99.2%, 95%, respectively. Finally, the base unit was the least efficient, such that total counts of total coliform, E. coli, and Aeruginosa were reduced by 95.9%, 97.2%, 90%, respectively, under same exposure time of the solar radiation. Comparing the obtained results with previous results, it may be concluded that this solar water disinfection method, which is based on the augmentation of the UV portion of the solar spectrum, is a promising one to be used to disinfect contaminated.