Anaerobic Digester

The Foster Brothers Dairy Farm built a anaerobic digester as a way to produce energy from the dairy's manure and to better manage nutrients on the farm.  Manure and milk house wastes from the dairy are collected and processed through the digester covered in the photos (below) by the collection bags.  Methane gas given off by the anaerobic bacteria munching on the wastes is collected under the flexible bags.  Anaerobic bacteria are bacteria that thrive in the absence of oxygen.  The gas is then transferred to another building where it is scrubbed (removing hydrogen-sulphide gas) and fed to an internal combustion engine connected to electrical generator.  In a recent development, the gas collection bag was divided into two bags as pictured to allow the facility to be used for full scale research with one side acting as a control. The digester has been in operation since 1982.  The digested effluent is separated and the solids are used as feed stock for compost.  The liquids are collected and spread on a growing crop where they are captured by the plants and don't end up as run-off in the streams. The electrical power generated feeds the farmstead which includes the dairy and young stock facilities as well as three residences.

The Foster Brothers digester with far bag inflated and near bag drawn down

Close-up of the digester gas collection bag

Vermont Natural Ag Products, Inc.
297 Lower Foote Street
Middlebury, VT 05753

Phone: 800-639-4511
Phone: 802-388-1137
Fax: 802-388-1135

Email: moodoovt@sover.net

© 2000 Vermont Natural Ag Products, Inc