Sixty percent of municipal wastewater treatment plant sludge dewatered by just two percent of the plants

Dec. 3, 2001 — The 16,000 municipal wastewater treatment facilities in the U.S. use sludge drying beds, mechanical dewatering, or some alternative to handle municipal sewage. Mechanical dewatering is the choice for the larger plants. McIlvaine Company has compiled information on these facilities and has identified each treatment process in the 4,000 plants larger than 0.7 million gallons/day (mgd) in a new online service entitled U.S. Municipal Wastewater Treatment Facilities and People.

While the larger plants are fewer in number they account for most of the wastewater treatment. For example, in New York there are 600 facilities. The 9 facilities between 100-1000 mgd process 4500 mgd. The 41 facilities 10-100 mgd process 2000 mgd. 138 facilities 1-10 mgd process 690 mgd. 244 facilities 0.1- l mgd process 122 mgd. 173 facilities 0.0-0.1 mgd process 10 mgd. So the top 2% of the facilities process more than 60% of the wastewater and the bottom 28% of the facilities process just 0.2% of the total wastewater.

Most plants larger than 0.7 mgd utilize mechanical dewatering of sludge. 85% of these plants use belt filter presses 5% use filter presses (plate and frame and recessed chamber) while the rest utilize centrifuges. However the centrifuges are the equipment of choice at larger facilities. New York City alone operates 80 centrifuges. Chicago, Los Angeles, Houston and other major cities utilize centrifuges for dewatering. So when centrifuges are compared to belt presses in terms of quantity of sludge handled they are the technology.

Increasing numbers of plants are opting for 3rd party operation of sewage treatment facilities. The numbers are still relatively small but at the present growth rate will become a significant segment of the total over the coming years. Land use accounts for the bulk of solids disposal. Some of the larger facilities sell fertilizer. Over 170 plants incinerate the sludge.

Many municipalities have discovered the Internet and have web sites devoted to descriptions of their facilities, postings of bid opportunities, and related subjects. These web sites have been identified and linked in the McIlvaine database U.S. Municipal Wastewater Treatment Facilities and People. For more information on this database click on www.mcilvainecompany.com or contact:

McIlvaine Company 2970 Maria Avenue Northbrook, IL 60062 Tel: 847 272 0010 Fax: 847 272 9673 E-mail: [email protected]