TIO2-ASSISTED DEGRADATION OF ENVIRONMENTALLY RELEVANT ORGANIC-COMPOUNDS IN WASTE-WATER USING A NOVEL FLUIDIZED-BED PHOTOREACTOR

The photocatalytic degradation of two environmentally relevant organic compounds [4-chlorophenol (4-CP) and p-toluenesulfonic acid (PTSA)] w as investigated using a novel cylindrical fluidized bed photoreactor ( FBPR). Accumulated biodegradable organic acids, identified as intermed iate reaction products, decreased after the removal of original pollut ants. Measurements of the oxygen uptake rates with a mixed culture sho wed that all intermediate photooxidation products were much better bio degradable than the initial aromatic pollutants (4-CP, PTSA). The infl uence of HCO3- and Cl- on the degradation rate was also studied. For c oncentrations of 1 mM bicarbonate (HO. radical scavenger) and of 140 m M chloride (photo-inhibitor), the photocatalytic degradation rate decr eased by 50%. During the photocatalytic reaction process, hydrogen per oxide accumulated in solution up to 0.21 mM depending on the initial c oncentration of the organic compounds and the concentration of dissolv ed oxygen. The relative quantum efficiency increased up to a factor of 2.3 by dosing of additional H2O2.