Hazardous organic matters in municipal sewage sludge in Taiwan

Application of municipal sewage sludge to agricultural land has attracted significant attention in recent years because it conserves abundant nutrients and hydrocarbons that can be used as a soil amendment. The presence of hazardous organic matters (HOMs) in sewage sludge limits the feasibility of reuse of sewage sludge. The purpose of this study was to investigate the types and the concentrations of HOMs in municipal sewage sludge in Taiwan. An efficient SFE/GC/MS method was used to determine HOMs in sludge samples. The results indicated that di-(2-ethylhexyl) phthalate (DEHP) was persistently found in both aerobically and anaerobically digested sludges. 4-nonylphenol (4-NP) was only found in anaerobically digested sludges. Both DEHP and 4-NP have been characterized as endocrine disrupting chemicals (EDCs) or environmental endorine disruptors (EEDs). It suggested that sludges containing high levels of DEHP and 4-NP need further treatment and reduction of possible impacts on the environment before their reuse as soil fertilizers.