HEI was founded in 1978 with the purpose of providing the design and installation of wastewater treatment equipment. HEI has successfully developed a library of knowledge on the economical treatment of toxic heavy metals, oil & grease, toxic hydrocarbons, suspended solids, and animal waste conversion. Our products include inclined plate clarifiers, Plate & Frame Filter Press and Recessed Plate Filter Press solutions, dissolved air flotation systems, sludge thickeners, sludge dryers, continuous polymer make-up and activation units, automatic sand filters, oil water separators and compact package treatment plants.