The treatment of 2,4-dichlorophenoxy acetic acid (2,4-d) herbicide by using photobiocatalysis from waters

In this study, removal of 2,4-Dichlorophenoxy acetic acid (2,4-D) herbicide from waters has been investigated by using a hybrid treatment system, which was a combination of chemical oxidation (photocatalysis) and biological treatment processes. Experimental studies are composed of two stages. In the first stage, the photocatalytic degradation and mineralization performance of the commercial grade Amin EXT 500 SL® 2,4-D amine salt herbicide was investigated by batch photocatalytic reactor system under laboratory conditions. Photocatalysis process (UVA+TiO2) of 25 mgL-1 were obtained as 97,47±0,27% degradation, 39,89±3,42% mineralization and 65,52±4,88% oxidation under UVA radiation (365 nm/36 Wm-2) at pH 5, at constant stirring rate (150 rpm) and temperature (22±1°C), under optimum conditions after 180 minutes. Moreover, in the same conditions, 99,74±0,08% degradation, 55,99±2,67% mineralization and 82,49±1,90% oxidation were obtained after 180 minutes of photocatalysis (TiO2+UVA+H2O2) using 25 mgL-1 of 2,4-D with optimum 150 mgL-1 H2O2. In the second stage of the study, maximum oxidation and herbicide degradation of 50 mgL-1 of 2,4-D were achieved at the end of the 4th day as 78,78±0,30% and 78,33±0,15% oxidation, as 38,23±3,12% and 42,26±0,42% degradation for the 6-days aerated (A-BR) and non-aerated biological reactor (NA-BR), respectively. For the treatment of effluent that was obtained from photocatalytic pretreatment for 15 min (P&B), was achived maximum values as 88,88±0,12% oxidation and as 87,14±0,75% herbicide degradation at the end of 4th day.