MUNICIPAL WASTEWATER SLUDGE DRYING TO CLASS A CASE REPORT ST. JOHN THE BAPTIST PARISH, LOUISIANA

This paper reviews technical and design considerations for the ultimate selection of heat drying to produce a Class A biosolids for one of the wastewater treatment plants of this Louisiana Parish. The final selection, the Fenton drying system, was placed as part of an upgrade to an existing facility during ongoing operations which took the plant from a drying bed arrangement to a Class A material. The author is Russell Raulston of Fenton Environmental Technologies, Inc.. Fenton is the equipment designer and manufacturer.St. John the Baptist Parish is located adjacent to Jefferson Parish and is a few miles north of the New Orleans International Airport. The River Road Wastewater Treatment Plant where this installation is located is in the Town of La Place. This area is mixed light and heavy industrial, agricultural and suburban. The population base is about 20,000. The treatment plant's daily flow is approximately 4.5 mgd. The Plant's biosolids practices had most recently been landfilling a gravity-dewatered cake in a commercial landfill 15 miles from the plant. Cake production averaged 3,000 cubic yards per year. With the 2002-2003 plant upgrade, a belt press and the SludgeMASTER RK 48 indirectly heated sludge dryer were added. The dryer is rated to dehydrate one ton of wet sludge cake per hour in batches of about 3 wet tons each. The drying system was housed in a newly constructed dewatering building with metal siding and including a small office and restroom facilities. The facility upgrade also included a dry product conveyor system with a by-pass allowing direct discharge from the belt press. Construction was completed in June 2003.To upgrade its biosolids processing to Class A, the Parish considered several alternatives and concluded that heat drying would meet its needs for producing a Class A biosolids with a neutral pH, compact and easily spreadable and with minimal limitations on application timing or technique. The heat-dried product can be used for a variety of horticultural and agricultural purposes using conventional spreading equipment.Fenton's automatic batch dryer is well suited to small to medium sized municipalities searching for an economical means of achieving Class A biosolids. It may be heated with natural gas, plant produced methane, landfill gas, fuel oil or propane.