Long-Term Objectives

1. Determine the role of a constructed wetland in an overall system to reduce total land requirements for swine waste management.

2. Evaluate the role and function of a media filter and overland flow in combination with a constructed wetland and lagoon to evaluate treatment train alternatives that provide maximum removal of nitrogen and phosphorus to minimize land requirements for total waste management.

3. Determine the maximum nitrogen loading rate for constructed wetlands by evaluating pilot wetland microcosms established to measure nitrogen transformations and growth of wetland plant species for serial nitrogen loading rates.

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Short-Term Objectives

1. Evaluate the capability of a constructed wetland to produce dischargeable effluent under the lowest recommended loading rate.

2. Evaluate the feasibility of using submerged cultures of rice and soybeans as wetland vegetation.

3. Evaluate performance of a constructed wetland system at loading rates that approach maximum levels of nitrogen that can be applied without damaging wetland plant species.

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Accomplishments

1. Continuous monitoring at the lowest recommended loading rate has verified that constructed wetlands cannot continuously provide a dischargeable effluent.

2. Constructed wetlands can provide a high level of nitrogen removal.

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Significance of Accomplishments

High interest in using constructed wetland systems for total swine waste treatment has developed because of some demonstration projects and trade magazine reports that constructed wetlands are a low-cost treatment system for providing a dischargeable effluent. However, constructed wetlands for animal waste treatment were not recommended in North Carolina because of basic theoretical concerns that wetlands cannot continuously provide a sink for nitrogen and phosphorus removal and concerns about aesthetics of wetlands currently in operation. This evaluation of constructed wetlands at the lowest recommended loading rate has verified that wetlands cannot continuously produce a dischargeable effluent. Therefore, our resistance to recommend constructed wetlands for swine waste treatment was justified and resulted in many producer benefits. Our current studies to evaluate the role of constructed wetlands in a waste management treatment system to minimize land requirements for terminal animal waste management is intended to provide producers with treatment system alternatives based upon documented performance.

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Future Plans

1. Continue to evaluate constructed wetlands at increasing nitrogen loading rates to determine their role in a treatment train consisting of an anaerobic lagoon, media filter, overland flow and constructed wetlands for maximum nitrogen and phosphorus removal to minimize land required for total waste management.

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Published by: North Carolina Cooperative Extension Service

Publication Number:

Last Electronic Revision: JULY 1996 (MSD)

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