February - May 2019. With excitement, we started our first journey! Despite a few kilometres on the road, there were no incidents and the trailer was set up within half a day, ready to measure after the bake-out. Particulate matter in the raw wastewater caused recurring problems with the bypass pump, which we solved with an optimized, automated back-flushing routine. Subsequently, measurements ran smoothly and the remote process control interface that we implemented proved to be extremely helpful.
During this deployment, our unit measured almost 2000 raw wastewater samples, originating from before and after the sand trap in the wastewater treatment plant’s influent. This implied bi-weekly cleaning, particularly of the filter unit. You can follow Michele during one of his typical maintenance days in Fehraltorf on higgs (German, with embedded Instagram posts in English) – thank you also Philipp and Benedikt for your support.
The subsequent analysis of treated effluent required almost no maintenance and we felt the automated measurements could have continued forever. We thank the open-minded, friendly staff from the wastewater treatment plant Fehraltorf for having hosted our first real-world application, and the urban water observatory team for their continued engagement.
A first evaluation of over 30 target compounds in the influent revealed almost as many distinctly different temporal patterns; thank you Pascale for your tremendous work during your semester thesis together with us. While some of these patterns observed at 20-minute resolution are plausible, others were really unexpected. Many of us probably would have struggled in accurately drawing a typical predicted pattern at this temporal resolution for most substances. We are looking forward what the non-target analyses will reveal …