RESUMO
Terpene-based cleaners are being widely used in industrial cleaning formulations because of their ability to replace suspected ozone-depleting chemicals such as 1,1,1-trichloroethane and 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113). Substitution of chlorinated solvents with ter-pene-based cleaners, however, is expected to result in increased discharges to wastewater from industrial operations. A pilot-scale study was conducted at the U.S. Environmental Protection Agency's (EPA) Test & Evaluation Facility in Cincinnati, OH, to quantify the fate of specific terpene compounds in the activated sludge wastewater treatment process. Biodegradation rates of terpenes were estimated from the difference between the influent terpene mass flow rates and the amounts volatilized to air, partitioned to waste sludge, and passed through the treatment process unchanged. Any chemical transformation of the terpene compounds studied was attributed to biodegradation. Analytical methods were developed to determine ter-pene concentrations in aqueous and gaseous media. The fate of two common terpene compounds (d-limonene and terpinolene) were evaluated in three identical pilot-scale systems: (1) a system with a high target spike range (2-10 mg/L), (2) a system with a low target spike range (0.5-2 mg/L), and (3) a control system (no spike). The study showed that the primary removal mechanism for the terpene compounds in the activated sludge process is biodegradation. Typically, greater than 90% of the mass of terpenes entering the aeration basin of the activated sludge process biodegrades to other compounds; volatilization from the reaction basin accounts for less than 10%, while loss to waste activated sludge and the secondary clarifier effluent accounts for less than 1%.
RESUMO
Primary effluent from a municipal wastewater treatment plant was used as the feed in bench scale activated sludge systems. These systems were spiked with disperse azo dyes at 1 mg 1-1 and 5 mg 1-1 levels and were sampled at various points in the process. Samples were analysed by high performance liquid chromatography with UV = visible detection and by thermospray ionization MS and tandem mass spectrometry (MS/MS) using direct injection or via column chromatography. The tandem mass spectrometry techniques were used both for method development purposes and for the specificity and extra information these techniques can provide. The investigation of the fate of disperse azo dyes in the activated sludge process was a major feature of this study. Major degradation products have been identified by tandem mass spectrometry analyses of these wastewaters. Precision and accuracy data generated by the thermospray tandem mass spectrometry technique are compared to those derived from the high performance liquid chromatography/UV-visible method.