1. 11. to 4. 11. 2021, I visited the department of environmental chemistry at Umea University. We were working out the list of biocides for further experiments to determine critical water concentration levels for bacterial resistance development. The selection was based on evidence in ECHA database and evaluation of HRMS screening data. We also visited a consultancy company interested in applying HRMS nontargeted screening to evaluate the treatment efficiency of advanced oxidation process technologies in wastewater treatment.