engleski

Treatment of chlorophenols in water matrix by UV/ferri-oxalate system: Part II. Degradation mechanisms and ecological parameters evaluation

The aim of the study was to evaluate mechanisms involved in degradation of p-CP in water matrix by UV/ferrioxalate (UV/Fe(OX)) system regarding the type of applied UV irradiation source (UV-C and UV-A). Besides the monitoring of parent pollutant degradation and the formation of its typical degradation by-products, the process effectiveness was evaluated on the basis of mineralization extent and changes in biodegradability and toxicity of p-CP model wastewater during the applied treatments. In Part I of the study, the optimal conditions for applied UV-C/Fe(OX) and UV-A/Fe(OX) were determined and used in this comparative study. Biodegradability is estimated over BOD5/COD ratio. The toxic effects were investigated on vibrio fischeri determining EC50 value. It was found out that p-CP degradation by UV-C/Fe(OX) process occurred via synergy of direct photolysis and radical mechanism, while radicals formed through photo-induced degradation of ferrioxalates played dominant role when UV-A/Fe(OX) process was applied. The presence of ferrioxalates strongly influenced the mineralization yield and improved biodegradability in the cases when UV-A and UV-C irradiation sources were applied, respectively. However, all applied processes yielded higher toxicity of treated water within observed treatment period presumably due to the presence of p-CP degradation by-products, which are more toxic than parent pollutant.

wastewater; para-chlorophenol; UV irradiation; ferrioxalate complexes; biodegradability; toxicity

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