Mass Fluxes of Linear Alkylbenzenesulphonates, Nonylphenol, Nonylphenol Mono- and Diethoxylate Through a Sewage Treatment Plant

Dissolved and particulate LAS, NP, N1PEO and NP2EO were determined in raw sewage, primary effluent, secondary effluent, primary and secondary sludge of the sewage treatment plant Zürich-Glatt on two consecutive sampling days. The results were combined with sewage flow rate and dry matter load measurements in order to obtain the respective mass fluxes. The latter provided information on the major removal processes affecting these detergent derived chemicals, i. e. biodegradation during the activated sludge treatment and incorporation into sludge. The overall removals of LAS over the two sampling days were 99.3% and 98.7% (w/w), of which 13% and 16%, respectively, were found in raw sludge and 9% and 13%, respectively, in anaerobically digested sludge. Both NP1EO and NP2EO were poorly removed in the secondary effluent and were educts for NP in sludge. Nonylphenol loads in the anaerobically digested sludge were 4.7 and 6.4 times larger than in the raw sewage.