10.4122/1.1000001166
Ort, C.
C.
Ort
Gujer, W.
W.
Gujer
Sampling for representative micropollutant loads in sewer systems
DTU Library, Technical University of Denmark (DTU)
2005
Conference full text
Household chemicals
micropollutants
measuring campaign
sampling strategy
sewer system
temporal variation
Swiss Federal Institute For Environmental Science And Technology And Swiss Federal Institute Of Technology
2005
en
10.4122/1.1000001165
application/pdf
Most commercially available auto-sampling devices do not support a continuous flow-proportional sampling mode, which would conceptually be the best for collecting representative composite samples. Instead different discrete sampling modes are available. Household chemicals can show considerable random short-term variations. With the anticorrosive benzotriazole, relating to a middle-frequent household activity, we show that, besides an accurate flow meter, mainly three factors are decisive for the representativeness of a substance\342\200\231s average load: the substance\342\200\231s load pattern, the sampling frequency and the length of the composite sample. When the sampling intervals are 10 minutes or longer, errors in the order of +/-40 % (standard deviation) or more have to be accepted, if the substance of interest is contained in a low number of wastewater pulses (i.e. the level of household activity). This particularly holds true for specific pharmaceuticals like e.g. carbamazepine. Ammonium would be less critical, because it relates to a large number of sources.