Effect of (partial) advanced oxidation processes (AOPs) on the decolourisation and biodegradability of an industrial wastewater

摘要

Synthetic dyes are among the major industrial pollutants and water contaminants. These coloured dye effluents cause serious environmental pollution problems by releasing toxic and potential carcinogenic substances. Traditional treatment techniques applied to remove colour from wastewaters, are chemical coagulation/flocculation, membrane separation or activated carbon adsorption. The overall result of these techniques is, however, only a phase transfer of the pollutant. In this paper, the potential contribution of partial chemical oxidation on the decolourisation and biodegradability of an industrial wastewater has been investigated. To this end, a coloured wastewater stream, originating from the graphical industry, is subjected to a treatment by the Fenton reagent, ozone, UV and O3/UV. An adjustment of the pH to 3 has been introduced as a pre-treatment step, resulting in a readily observable decolourisation of the wastewater. The results show that, after precipitation, each oxidation process can achieve a complete irreversible decolourisation of the wastewater. Based on the biodegradability, the ozone experiments and the combination of ozone and UV light realise the highest improvement for the BOD/COD ratio from 20% to respectively 28% and 37%. These observations clearly confirm the synergetic effects of combining UV and ozone for these wastewaters. Finally, the economical feasibility of the selected techniques is considered.