Inactivation of Fecal coliforms during solar and photocatalytic disinfection by zinc oxide (ZnO) nanoparticles in compound parabolic concentrators (CPCs)

摘要

Water samples of 0, 50, and 100 nephelometric turbidity units (NTU) spiked with fecal coliforms (107 CFU/ml) were exposed to natural sunshine in 1l quartz glass tubes fitted with rectors’ compound parabolic concentrators CPCsubS/sub at two forms CPCsub1/sub (whit nanoparticle zinc oxide) and CPCsub2/sub(without nanoparticle zinc oxide). The samples were characterized using the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). On clear days, the complete inactivation times (more than 7-log unit reduction in bacterial population) in the systems with CPCsub1/sub, and CPCsub2/sub were 15, and 30 min, respectively. The maximum temperatures obtained in the water samples were 80 for CPCsub1/sub, and 82 for CPCsub2/sub. The use of CPCsub1/sub with hydroxyl radicals (OHsup?/sup) production significantly improved the efficiency of the old CPCsubS/sub technique, since these systems (CPCsub1-2/sub) shortened the exposure times to solar radiation and also minimized the negative effects of turbidity and also regrowth was zero in the disinfected samples. Due to two simultaneous effects of high temperatures and UV, regrowth in most ways of solar disinfection was not seen in these examples. Overall, this technology has been proved to be a good enhancement method to inactivate microorganisms under real conditions and represents a good alternative technique to drinking water treatment.