Experiments in waste processing for undergraduates

The emphasis on hazardous waste processing and pollution prevention in the Department of Chemical Engineering, University of Minnesota, Duluth (UMD), has been enhanced by a National Science Foundation Instrument and Laboratory Improvement (NSF ILI) grant. It funded the development of 6 new experiments for the laboratory classes and for demonstrations in lectures. Two experiments provide the students with training in important techniques of analysis for waste streams. Wastewater is characterized by the measurement of the biochemical oxygen demand (BOD), a quantity vital for the assessment of discharges to receiving waters. We have built a simple flue with a burner in the laboratory to train the student in the use of a stack-gas analyzer. This measures the excess air, gas temperature and the concentrations of the common pollutants CO, CO₂, NO_x and SO₂ in flue gas. Four experiments teach techniques of separation. A solvent, methanol, is removed from water in our custom-built continuous distillation unit. Salt is removed from brine with our purpose-built reverse osmosis system. Ultrafiltration is used to separate dextran blue and riboflavin in an aqueous solution. Finally, heavy metal ions in water are replaced by benign cations in our ion-exchange unit.