engleski

Treatment of chlorophenols by UV-based processes: correlation of oxidation by-products, wastewater parameters and toxicity

The aim of the study was to evaluate the toxicity and biodegradability of para-chlorophenol (p-CP) model wastewater when treated by UV and UV/H2O2 processes. We investigated the correlations between the toxicity and the concentration of p-CP and its oxidation by-products as well as other parameters with summarizing characteristics which potentially indicate hazardous water components ; e.g. AOX (adsorbable organic halides), TOC (total organic carbon), COD and BOD5 (chemical and biochemical oxygen demand). Biodegradability is estimated over BOD5/COD ratio. The toxic effects were investigated on luminescent bacteria vibrio fischeri determining EC50 value. The correlation between each data pair was estimated using statistical approach calculating the Spearman rank coefficients. The biodegradability of p-CP model wastewater was improved by UV/H2O2 process ; BOD5/COD ratio increased from 0.37 to 0.73 after 1h treatment (F = 1243 mJ cm-2). According to the calculated Spearman rank coefficient the highest correlation with toxicity data among all monitored parameters was obtained for hydroquinone and benzoquinone, as by-products of p-CP degradation, as well as for BOD5/COD ratio.

wastewater ; para-chlorophenol ; UV irradiation ; toxicity ; statistical analysis

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