The performance of an alternately operated activated sludge wastewater treatment plant (WWTP) has been investigated with respect to six phthalates, nonylphenol (NP) and nonylphenol diethoxylate (NPDE) and linear alkylbenzene sulphonates (LAS). Samples of raw sewage, primary and secondary sludge and treated water were collected during an 8-day period in May 1999 and analysed for dissolved and sorbed substances. To evaluate the system performance with respect to substance removal through biodegradation and sorption to sludge the measured data were applied in a model describing the different bioreactors as one single reactor, corresponding to the concepts of, e.g. SimpleTreat. The most abundant of the investigated phthalates was di-(2-ethylhexyl)-phthalate (DEHP) with a measured mean inlet flow of 240g/day. Two percent of this amount was found in the treated water, 70% was biodegraded and 28% was found in the sludge. For LAS the mean inlet flow was 20,300g/day, of which less than 1% was found in the treated water, 84% was biodegraded and 15% was found in the sludge. The mean inlet flow of NP and NPDE was 44 and 590g/day, of which 4% and 2% was found in the treated water, 80% was biodegraded for both substances, and 16% and 18% was found in the sludge, respectively. The WWTP removal of the investigated substances was thus high compared to other studies of conventional activated sludge WWTPs. The simple model set-up presents a strong tool for predicting substance removal and system sensitivity related to changes in the inlet conditions, such as concentrations and flow. Furthermore, it allows the inclusion of complex alternately operated WWTPs in risk assessment tools such as e.g. SimpleTreat.
[1]
L. Carlsen,et al.
Solubilities and surface activities of phthalates investigated by surface tension measurements
,
2001,
Environmental toxicology and chemistry.
[2]
Plassche Ej van de,et al.
Environmental risk characterization of 4 major surfactants used in the Netherlands
,
1995
.
[3]
W. Giger,et al.
Behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment—I. Occurrence and transformation in sewage treatment
,
1994
.
[4]
M. Thomsen,et al.
Sensitivity analysis of calculated exposure concentrations and dissipation of DEHP in a topsoil compartment: the influence of the third phase effect and dissolved organic matter (DOM).
,
2002,
The Science of the total environment.
[5]
D. van de Meent,et al.
A spreadsheet-based box model to predict the fate of xenobiotics in a municipal wastewater treatment plant
,
1991
.