NYS Governor's Awards for Pollution Prevention - AA Dairy
AA Dairy, Candor
The AA Dairy is a 550 cow dairy operation with a 2,200 acre land base located in Candor. This three partner family owned dairy has successfully installed an anaerobic digestion system to reduce odor, improve water quality, and improve community relations while contributing to the profitability of the farm operation by producing electricity from the methane generated by the anaerobic degradation.
Methodologies and Procedures
The basic concept was to install a digester with a 1000 cow capacity into the current farm system using the maximum amount of existing equipment, facilities and skills already present. The digester is a 140 feet long, 32 feet wide and 14 feet deep buried concrete manure storage tank with an air-tight expandable black rubberized dome to trap a biogas mix of methane, carbon dioxide and hydrogen sulfide rising from the incoming manure that is kept at 99 degrees F. A FAN fiber separator, a Caterpillar® 3306 natural gas engine connected to an electrical generator, and a liquid storage lagoon are also features of this project.
At least 15,000 gallons of manure are fed into the digester per day, and as this is fed in one end, an equal amount is pushed out the other end. During the digestion process, which takes 40 days for each daily "plug" to move through the digester, biogas builds up under the black dome. The biogas consists of approximately 60 percent methane. The gas is collected, filtered, measured and slightly pressurized before being used to fuel the natural gas engine. Exchangers transfer heat from engine hot water loops to another loop which store hot water in a 4000 gallon tank. Stored hot water is available to warm the digester and for other farm needs. Excess electrical power is sold to NYSEG.
The digested material is pumped to a FAN screw press solid separator. Recovered solids have the physical characteristics of moist peat moss, a dry matter content of 25 - 28 percent, a pH of 8+ and are essentially devoid of weed seeds. This fiber is collected and moved to a paved composting area. The fiber is not mixed with any other materials but still achieves about 150 degrees F in a few days. The composted fiber is sold to a soil blender and to local land owners.
The almost odorless liquid nutrient, which is approximately 90 percent volume of the original manure, is deposited in the lined liquid storage lagoon. The lagoon is designed to hold 2.3 million gallons and is lined with plastic. The liquid nutrient will be irrigated with a "traveling gun" system in the future. Presently, the liquid nutrient is applied to cropland by use of 4000 gallon slurry wagons.
The sale of composted solids have greatly helped to recover the high cost of the implementation of this environmentally sound process.
Savings resulted from producing its own electricity and selling the excess back to the utility.
The environmental impact, especially on the ground water quality, has been reduced.
The benefits to the community in odor reduction makes for better neighbor relations.
The ability to irrigate directly on the growing crops with virtually no loss of nutrient value.
Any comments or questions?
Contact us at: 625 Broadway, Albany, NY 12233-1750;
518-402-9469 (phone); 518-402-9168 (fax)
This page was last modified April 21, 2000