LAND APPLICATION OF SEWAGE SLUDGE: THE TOLUENE ISSUE

摘要

In order to gain more insight into the origin of organic pollutants in sewage sludge a thorough characterisation of the major streams (influent, effluent, sewage sludge and intermediate streams) in two WWTP's; one with and one without sludge digestion; was conducted. The only pollutant that was found present in significant concentrations in the sewage sludge and in lower concentrations in some of the intermediate streams was toluene. Toluene levels depended highly on whether a sludge digestion was present or not. Literature data indicate the possibility of toluene formation through inhibited methanogenic fermentation, which was confirmed through lab-scale tests. Possible remedies to prevent the formation of toluene in sewage sludge are also discussed.