Rental of installations for treating and, in particular, for recycling of sewage and potable water as well as of equipment for feeding air or oxygen in waste water; development of processes and construction of installations for other for treating and, in particular, for recycling of sewage and potable water as well as of mobiles test installations; development of processes and construction of equipment for feeding of oxygen in sewage and potable water for other; technical consulting on special sewage and potable water treatment processes and realisation of studies on sewage and potable water treatment problems; realisation of tests for other for treating and, in particular, for recycling of sewage and portable water