Much of the content of household sewage consists either of food products which made their way into the garbage disposal rather than into a human body, food which made it through the body without being absorbed, and waste products produced by the body along with wastes from cleaning operations such as the washing of bodies, dishes, floors and automobiles. Industrial wastes are highly variable but should not contain hazardous chemicals. Street runoff often contains oils and grit. Newer systems keep street runoff separate from sewage. The treatment of urban sewage generally consists of three phases, screening and grit removal, primary treatment, and secondary treatment.
Few plants carry out tertiary treatment.
Prior to the visit to the sewage treatment plant you should answer the following questions using your textbook and other resources as needed. You may write your answers on these sheets. One of the best plants to tour is the Chicago Metropolitan Water Reclamation District plant in Stickney. Your instructor will arrange a tour. As we move through the sewage treatment plant answer the following questions.