Design and construction 18 Purification 14 Sewage disposal plants 12 Sewage 10 Management 9 Water 7 Chemical plants 6 más ... Equipment and supplies 6 Maintenance and repair 6 Plant engineering 6 Plant maintenance 6 Water treatment plants 6 Electric power systems 5 Steam power plants 5 Water-supply engineering 5 Electric motors 4 Environmental aspects 4 Heat 4 Lighting 4 Materials handling 4 Protection 4 Transmission 4 Vibration 4 Air conditioning 3 Analysis 3 Boilers 3 Chemical engineering 3 Chemical processes 3 Combustion 3 Condensers (Steam) 3 menos ...