SOLAR PHOTOCATALYSIS FOR REMOVE EMERGING CONTAMINANTS IN WASTEWATER

Conventional municipal wastewater treatment plants are not able to entirely degrade some organic pollutants that end up in the environment. Within this group of contaminants, Emerging Contaminants are mostly unregulated compounds that may be candidates for future regulation. In this work the application of different solar driven oxidation processes: photolysis, solar titanium dioxide photocatalysis (TiO2), solar photo-Fenton using peroxymonosulfate as oxidant (PMS/Fe(II)) are studied as tertiary treatments for the remediation of micropollutants spiked in real municipal wastewater treatment plants effluents at pilot plant scale. The examined pollutants were a multicomponent solution at low concentration level (10 µg L−1 at maximum 1 mg L-1) of herbicides and pharmaceutical compounds: sulcotrione, mepanipyrim, 2-methyl-4-chlorophenoxyacetic acid, ibuprofen and diclofenac. A solar panel pilot plant was used for the photocatalytic experiments. The process was mainly evaluated by a fast and reliable analytical method based on a HPLC system. Solar titanium dioxide (0.7gr L-1) and photo-Fenton process using low iron and peroxymonosulfate doses ([Fe(II)] = 100 µM ; [PMS] = 200 µM) were proved to be an efficient methods for the elimination of these compounds with relatively high degradation rates. Independently of the oxidation method assessed, the photocatalytic degradation of multicomponent mixture of emerging contaminants with solar advanced processes followed apparent first-order kinetics. Preliminary results showed that the order of micropollutants elimination efficiency under the experimental conditions evaluated was solar heterogeneous photocatalysis with TiO2 > solar PMS/Fe(II) >solar photolysis