Historically animal manures have been handled as a solid and were either deposited directly to pasture by the animals or collected along with the bedding used in the animal shelter and applied to land as a crop nutrient. As the number of animals on farms has increased the need for more efficient methods of manure management has also developed. The emphasis of the resources on these web pages are to provide an overview of manure treatment technologies, research being done in this field, and highlight the considerations involved in selecting candidates for a particular farm.
Why Treat Manure?
Manure from animals is a very wet, bulky material, containing as much as 90% water. Of the 10% that is dry matter, much of it is carbon. The manure handling system can impact the characteristics of the animal waste stream. Water-based waste management systems may have a liquid stream with greater than 98% moisture while manure scraped from open lots can contain a very high percentage of soil. As a result, the plant nutrient content of the manure is a very small portion of the weight/volume. Hauling nutrients to cropland in the form of manure can get very expensive compared to hauling the same amount of nitrogen or phosphorus in the form of commercial fertilizer.
Correcting the imbalance in manure nutrient distribution will involve finding ways to economically move excess nutrients off the livestock or poultry farm. Many alternatives to land application of raw manure are being examined. Many of these “manure treatment technologies” have been used in one form or another for many years, while others are recent solutions. Often, technologies are used in combination to create a system that can be tailored to the species, management of the farm, climate, or other factors. Technology that may be very successful on one farm may not be appropriate for another.
Manure Treatment Technology is Not “One Size Fits All”
Treatment technologies are generally selected to meet specific treatment goals on the farm. These treatment goals include nutrient reduction (primarily nitrogen and phosphorus), odor reduction, volume reduction, energy recovery, and adding value to the manure. Manure treatment technologies are often linked together to address several challenges faced by animal producers such as excessive nutrient on farm, manure runoff and odor. There may be additional benefits to manure treatment technologies beyond the primary treatment goals such as the reduction of emissions of particulate matter or greenhouse gases.
| Nitrogen Reduction | Phosphorus Reduction | Odor Reduction | Energy Recovery | Adding Value to Manure |
| Aerobic Treatment | Manure Additives | Solids Separation
Covers |
Anaerobic Digestion
Thermal Technologies (Gasification, Combustion, Pyrolysis) |
Composting |
Recommended Reading About Manure Treatment Technologies
- Livestock and Poultry Environmental Stewardship (LPES) Curriculum Lesson 25: Manure Treatment Options
- Development of Environmentally Superior Technologies (Smithfield Agreement)
Author: Mark Rice, North Carolina State University
