The Riverside Company, a global private investor focused on the smaller end of the middle market, has closed the acquisition of Arbeidsmiljø og Energiteknikk AS, a Norwegian distributor of third-party consumables and laboratory / cleaning equipment, from RA Service AS and management. The investment is an add-on to Riverside's portfolio company Dastex Reinraumzubehör GmbH & Co. KG, a specialized cleanroom garment and consumables distributor in Europe.