VOLATILE ORGANIC-COMPOUNDS IN DIGESTED UNITED-KINGDOM SEWAGE SLUDGES

This paper describes a liquid-liquid extraction method using GC-ECD/FI D detection developed for the analysis and identification of volatile organic compounds (VOCs) in liquid sewage sludges. The VOCs studied we re as follows: 1,1-DCE; 1,2-DCE; 1,2-DCA; chloroform (CCl3H); 1,1,1-TC A; 1,1,2-TCA; TCE; carbon tetrachloride (CCl4); tetrachloroethene (PCE ); 1,1,2,2-tetrachloroethane (1,1,2,2-PCA); benzene; toluene; ethylben zene; o-, and m- plus p-xylene. n-Pentane was the most efficient of se veral solvents at extracting the VOCs from sludges, and recoveries of all but two were >80 %. The VOC concentrations of 12 digested sludges obtained from rural, urban, and industrial treatment works in northwes t England were investigated. Total VOC concentration ranged from 4.62 to 568 mg/kg dry weight (260-15 400 mug/L), with a mean of 105 mg/kg ( 2810 mug/L). Toluene was present at the greatest concentration. There was a significant correlation between concentrations of ethylbenzene, m- plus p-xylene, o-xylene, TCE, and PCE in the sludge samples. There was no apparent relationship between the sludge VOC concentrations and the volume of industrial input to the sewage treatment works (STW), i nfluent treatment, population served, and sludge solids content. The s ludge application to agricultural land was unlikely to increase the VO C concentration of the soil to levels which may cause concern for huma n health and the environment.