This year, environmental engineering celebrates the 40th anniversary of its presence in the scientific centre in Zielona Góra. It was part of the Higher School of Engineering in Zielona Góra, the Technical University Zielona Góra and it is part of the University of Zielona Góra. We have just had a celebration organized by the Institute of Environmental Engineering, in the form of an anniversary session, an international conference and a meeting of graduates. We would like to thank all the participants of these events. You made these celebrations truly special and they will be remembered both by the organizers and the participants.