Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.
This Technology is Applicable To:
Species: Swine, Dairy, Poultry
Use Area: Manure Storage
Technology Category: Aeration
Air Mitigated Pollutants: Odors
System Summary
A surface aeration system composed of an aerator module with six venturi air injectors has been demonstrated to effectively reduce odor level (measured by odor detection threshold) emitted from an operating swine manure anaerobic lagoon. Past research reports have shown that partially aerating manure can reduce the power consumption by up to 80% as compared to full aeration, while still achieving satisfactory odor amelioration. Data from this project provide further evidence that it is not only feasible but also affordable for animal producers to consider using this technology to control odor. A reduction in odor detection threshold by about 67% was achieved after the surface aeration system started operation in the test lagoon for about 10 days. It was also observed that the aeration treatment could maintain a dissolved oxygen level of 0.3 mg/L in the top lagoon liquid and the aerated layer worked like a biological cover that had the capability of destroying the odorous compounds passing through it. Although the surface aeration technology presented in this paper is tested in swine manure lagoons, it is expected that the technology can also be applied to manure lagoons of other animal species such as dairy and poultry. As a matter of fact, there are already experiments being carried out on a poultry lagoon in Texas using the same aeration apparatus, the results from which will be compared with those presented here. It is anticipated that the aeration system will be available to animal producers in the near future.
Applicability and Mitigating Mechanism
- The surface aeration system can be applied to any open liquid manure storage facilities
- Odorous compounds are intermediate products during anaerobic digestion and, without treatment, they will be emitted into air causing odor problems
- Aeration is to provide oxygen to the aerobic microorganisms in the liquid so that they can actively decompose these odorous compounds
- Surface aeration establishes a biological cover in which aerobes use the provided oxygen to clean up the odorous materials before they reach the air
Limitations
- This technology is not suitable for in-barn manure storage structures such as deep pits
- Since the surface aeration system is placed outdoors, the ambient temperature should always be above freezing point so the technology cannot be used in northern states of the country in winter.
- Ammonia emission from the lagoon liquid under treatment may be increased due to increased pH in the liquid and the mixing effect
Cost
The capital cost of this surface aeration system is relatively inexpensive and all the venturi air injectors are commercially available (under $200/each). For a one-acre lagoon, the equipment cost including materials and installation may be anywhere between $10,000 and $15,000 and the running cost (for a 4.5 horsepower pump running 24 hours a day, 365 days a year) will be 4.5 hp x 0.75 kW/hp x 24 h/day x 365 day/year = 29,565 kWh. Assuming the price per kWh being at $0.07, the total annual cost for the operation will be 29,565 kWh x $0.07 = $2,070. Considering the particular lagoon receiving manure from 4,000 head finishing pigs and 2.5 production cycles a year, the treatment cost per pig marketed is only around 21 cents.
Authors
Jun Zhu1, Chunying Dong1, Cutis Miller1, Liang Wang1, Yecong Li1, Saqib Mukhtar21University of Minnesota, 2 Texas A&M University
Point of Contact:
Jun Zhu, zhuxx034@umn.edu
The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.