Effluent Treatment Plant (ETP) Welco engineering Ltd. is a global leader in the design and manufacture of wastewater treatment plant equipment. This includes innovative, robust, and energy-efficient engineered membrane diffusers. These include fine bubble diffusers, coarse bubble diffusers, and aeration systems. Our wastewater process division specializes in the moving bed biofilm reactor (MBBR) and integrated fixed-film activated sludge (IFAS) processes. We focus on solutions for both industrial wastewater treatment plants and sewage treatment plants.