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Barham Farms Utilizes Nutrients to Grow Tomatoes
| Location |
Zebulon, North Carolina |
| Project Type |
Farm scale |
| Animal Type |
Swine (farrow-to-wean) |
| Population |
4,000 sows |
| Baseline System |
Anaerobic lagoon |
| Digester Type |
Covered lagoon |
| System Designer |
RCM International, LLC |
| Biogas Use |
Boiler |
| Project Size |
120 kW Caterpillar 3406 engine; 0.4 MMBtu/hr boiler |
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| Photo: North Carolina State University |
When the owner of Barham Farms became interested in reducing odors and improving water quality in 1995, he contacted the AgSTAR program. AgSTAR provided design and technical support for the installation of a covered in-ground digester and methane recovery and utilization system. Today, the project provides hot water for the farm and nutrient-rich wastewater feeds 14,000 tomato plants.
Manure from the pull plug pit is first treated in an in-ground ambient temperature anaerobic digester. Methane gas is extracted and delivered to a boiler, which produces hot water that is used on the farm. A portion of the hot water has been used to heat pig mats under the farrowed pigs, displacing the use of heat lamps.
Effluent from the digester flows to a second-stage storage lagoon. A trickling nitrification biofilter treats a portion of the stored effluent that is used to recharge the pits. While some of the treated wastewater is applied to coastal Bermuda grass, the majority is piped to two 28,000 ft2 greenhouses. An automated irrigation system applies about 12 m3 per day of the nutrient-rich wastewater to the tomato plants, which produce about 1,500 pounds of marketable fruit each day.
When the project began, the 120 kW engine generated electricity for on-farm use as well as for sale to the local utility. However, the inability to secure a mutually beneficial contract between the farm and the utility has forced the shutdown of this element of the project.
Barham Farm's digester includes the following benefits:
- Odor is virtually non-existent, reducing impact on large subdivisions less than a mile away
- Methane recovery system produces a large portion of the hot water required for swine production, saving energy costs
- Manure treatment and nutrient application complies with manure management regulations, saving additional investment
- Stored wastewater provides nutrients for the greenhouse operation, which produces a value-added product and reduces the application of digester effluent to the spray fields
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