Discharge of three benzotriazole corrosion inhibitors with municipal wastewater and improvements by membrane bioreactor treatment and ozonation.
A set of three benzotriazole corrosion inhibitors was analyzed by liquid chromatography-mass spectrometry in wastewaters and in a partially closed water cycle in the Berlin region. Benzotriazole (BTri) and two isomers of tolyltriazole (TTri) were determined in untreated municipal wastewater with mean dissolved concentrations of 12 microg/L (BTri), 2.1 microg/L (4-TTri), and 1.3 microg/L (5-TTri). Removal in conventional activated sludge (CAS) municipal wastewater treatment ranged from 37% for BTri to insignificant removal for 4-TTri. In laboratory batch tests 5-TTri was mineralized completely and 4-TTri was mineralized to only 25%. This different behavior of the three benzotriazoles was confirmed by following the triazoles through a partially closed water cycle, into bank filtrate used for drinking water production, where BTri (0.1 microg/L) and 4-TTri (0.03 microg/ L) but no 5-TTri were detected after a travel time of several months. The environmental half-life appears to increase from 5-TTri over BTri to 4-TTri. Treatment of municipal wastewater by a lab-scale membrane bioreactor (MBR) instead of CAS improved the removal of BTri and 5-TTri but could not avoid their discharge. Almost complete removal was achieved by ozonation of the treatment plant effluent with 1 mg O3/mg DOC.
Weiss
Stefan
S
Department of Water Quality Control, Technical University of Berlin, Sekr KF 4, Strasse des 17 Juni 135, 10623 Berlin, Germany.
Jakobs
Jutta
J
Reemtsma
Thorsten
T
D001673:Biodegradation, Environmental; D019149:Bioreactors; D002853:Chromatography, Liquid; D005858:Germany; D006207:Half-Life; D013058:Mass Spectrometry; D010126:Ozone / Q000737:chemistry; D014230:Triazoles / Q000032:analysis* / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
D014230:Triazoles; D014874:Water Pollutants, Chemical; D010126:Ozone; C012771:benzotriazole