Chemical wastes and bacteria in this lagoon system have brought the State Water Resources Commission's lowest rating of 'E' to Gelman Instrument Co of Ann Arbor, an innovator and manufacturer of devices for measuring and controlling air and water pollution. The aerator at the center of the nearest lagoon has proven inadequate. The platform and box in the foreground, built this week, will contain a sampling and measuring device developed by a University professor which the firm hopes will lead to a solution of the odor-creating problem.