Destruction of toxic organics in water by an injection-type downflow UV/O-3 oxidation reactor

An injection-type downflow UV/O-3 oxidation reactor (IDUOR) was developed m ainly with the combination of a configuration of two concentric cylinders w ith the UV lamp in the bottom axial position and a downflow mixing gas-liqu id injector. This configuration leads to atomizing of the solution resultin g in higher levels of dissolved ozone which is then illuminated by UV light to generate hydroxyl radicals. Four different toxic wastewaters including 4-chlorophenol, carbofuran, dye-auxiliaries and pesticide wastewater with a COD range of 164 to 1602 mg/L and a microtoxicity (EC50) range of 3.008% t o 19.062% were used to investigate the performance of the device. It was fo und that the ozone utilization efficiency attained was more than 75% with v ery satisfying COD and TOC reduction for wastewater treated with IDUOR. The IDUOR when compared to a conventional stirred bubble UV/O-3 reactor exhibi ted increased efficiency for ozone utilization and GOD, TOC, microtoxicity reduction. Also, the pseudo-first rate constants on the basis of COD and TO C reduction indicated much higher oxidation rate of organics in IDUOR, prov iding additional evidence of the considerable treatment potency of IDUOR fo r destruction of toxic organics in water.