Solar pilot-scale photocatalytic degradation of microcystin-LR

A solar immobilized-catalyst photocatalytic reactor design and TiO2 attachment procedure is presented. The reactor is used to remove cyanobacterial toxins from drinking water samples spiked with trace levels of microcystin-LR (MLR). The reactor is randomly packed with TiO2 coated ceramic Raschig rings, which provide a large surface area without compromising aperture area. The true quantum efficiency of the reactor ranges from 2.4 - 2.8% for dichloroacetic acid mineralization. At pH 7, no. removal of NILR is observed under simulated dark conditions suggesting that adsorption and air stripping have negligible effect in the removal of microcystin-LR from drinking water. Rapid removal of MELR is observed once exposed to sunlight and little difference is detected between the removal rates under cloudy or sunny conditions. The virtual independence of degradation rates for low to moderate levels of cloud cover is due to the ability of the non-concentrating reactor to harness diffuse light (unlike concentrating reactors which require direct irradiation) and minimize reflection losses.