Applied Engineering Technologies

Applied Engineering Technologies (AET), based in Ann Arbor, Michigan, developed the Treatment Shaft — a patented underground vertical wastewater treatment system designed to provide capture, storage, and complete treatment of Combined Sewer Overflow (CSO) and Sanitary Sewer Overflow (SSO) events. The Treatment Shaft integrates screening, settling, skimming, disinfection, and dewatering within a single compact underground structure, using a vertical baffle wall that creates U-shaped flow to prevent short-circuiting and ensure adequate disinfection contact time. During routine storms the shaft captures the entire overflow volume; during larger events, flows exceeding storage capacity receive full treatment before discharge. Screenings are removed by hydraulically-activated combs, and settled solids are re-suspended via a proprietary high-pressure nozzle flushing system before dewatering by submersible chopper pumps back to the sewer interceptor. AET also developed the Dual Treatment Shaft, which employs two vertical shafts to deliver primary, secondary, and tertiary treatment of sanitary wastewater — the first shaft handling physical-chemical treatment and the second providing biological treatment and disinfection. The Treatment Shaft occupies less than 15% of the footprint of conventional surface storage systems and operates with gravity-driven flow and minimal operator involvement. The technology received the EPA PISCES Award in 2006 and was listed as an EPA Emerging Technology in 2013.