Suitability of Chemcatcher® passive sampling in monitoring organotin compounds at a wastewater treatment plant

Municipal wastewater contains a number of harmful chemicals whose concentrations can fluctuate dramatically. Therefore studying concentrations of harmful chemicals by conventional grab water sampling can give a misleading picture of the true chemical contents. In grab samples the contents can often remain below the quantification limit which does not necessary mean the compound is not present in the aquatic environment but rather implies unsuccessful timing of sampling or limited sample volume. Alternative techniques are needed to improve the reliability of monitoring harmful chemicals and thus in this study the presence of organotin compounds (OTCs) was monitored at a wastewater treatment plant (WWTP) with Chemcatcher® passive sampling. Extreme conditions complicate the passive sampling, particularly in influent stream. However, the OTC concentrations determined with passive samplers were similar with those measured from grab samples. In conclusion, fewer OTCs were found with grab sampling than with passive sampling, particularly in effluent. The passive samplers seemed to be more suitable than grab samples for monitoring OTCs in wastewaters. As long-term sampling techniques give a more representative picture of the true chemical contents, passive sampling should be considered as an emerging tool for environmental authorities to implement the monitoring of harmful chemicals at WWTP.