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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #249072
Title: Plant growth and elemental uptake by floating vegetation on a single stage swine wastewater lagoon

Author
item Hubbard, Robert
item Anderson, William - Bill
item NEWTON, G - University Of Georgia
item RUTER, JOHN - University Of Georgia
item Wilson, Jeffrey - Jeff

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2011
Publication Date: 7/15/2011
Citation: Hubbard, R.K., Anderson, W.F., Newton, G.L., Ruter, J.M., Wilson, J.P. 2011. Plant growth and elemental uptake by floating vegetation on a single stage swine wastewater lagoon. Transactions of the ASABE. 54(3):837-845.

Interpretive Summary: Contamination of surface and ground waters is an environmental concern. Pollution from both point and nonpoint sources can render water unsuitable for use. Lagooned wastewater from confined animal feeding operations (CAFO’s) represents an extreme in water quality problems. Wastewater lagoons are used for primary treatment which includes settling of solids and loss of gases by volatilization. Additional methods are often used to treat the wastewater from the lagoons. These methods include passing the wastewater through constructed wetlands, where both plant uptake and biological processes such as denitrification remove or retain nutrients. A new concept for improving surface water quality, including that of wastewater lagoons, is to grow vegetation on floating platforms in the water body. A study was conducted from 2005-2008 to determine the feasibility of growing vegetation on platforms in a swine wastewater lagoon. Based on plant screening in 2005 five species were selected that showed potential for producing biomass on floating platforms in wastewater. The five species were common bermuda grass, Tifton 85 bermuda grass, St, Augustine grass, Fall panicum, and Giant reed. The replicated study showed that three of the species, common bermuda grass, Tifton 85 bermuda grass, and fall panicum grew well in the highly contaminated wastewater. The greatest biomass production (sum of six cuttings) was 3559 g m-2 dry matter from the Tifton 85 bermuda grass followed by common bermuda grass (3214 g m-2 dry matter) and fall panicum (3082 g m-2 dry matter). Nutrient (N, P, and K) uptake and removal from the wastewater was primarily a function of biomass produced. The greatest annual removal of nutrients from the wastewater was by the Tifton 85 bermuda grass in 2006 where the floating vegetation removed 690 and 250 kg ha-1 N and P in three cuttings of the vegetation. The study showed that plant species exist which can grow and thrive on anaerobic wastewater lagoons on floating platforms for at least two years while removing N, P, and K from the wastewater. This technology has potential for utilizing nutrients in wastewater to produce biomass, which then can be used as a soil amendment, while protecting environmental quality of the nation’s surface waters.

Technical Abstract: Methods are needed for utilizing nutrients contained within animal wastewater lagoons. One potential method for removing nutrients is to have vegetation growing on the lagoon. A study was conducted from 2005-2008 to determine the feasibility of growing vegetation on floating platforms on a single stage swine wastewater lagoon. Five species (common bermuda grass (Cynodon dactylon (L.) Pers.), Tifton 85 bermuda grass (Cynodon dactylon (L.) Pers.), St. Augustine grass (Stenotaphrum secundatum (Walter Kuntze)), fall panicum (Panicum dichotomiflorum (L.) Michx.) and giant reed (Arundo donax (L.)) were selected from earlier studies as having potential for growth on a commercial swine farm wastewater lagoon. The plants were periodically harvested as needed and the biomass was weighed and analyzed for N, P, K, Ca, Mg, S, Al, B, Cd, Cr, Cu, Fe, Mn, Mo, Na, Ni, Pb, and Zn. In 2008 weeds that had populated the mats were harvested for biomass and elemental uptake. The greatest biomass production (sum of six cuttings) was 3559 g m-2 dry matter from the Tifton 85 bermuda grass followed by common bermuda grass (3214 g m-2 dry matter) and fall panicum (3082 g m-2 dry matter). All of the plant species accumulated greater than 1000 ppm Na. Nutrient (N, P, and K) uptake and removal from the wastewater was primarily a function of biomass produced. The greatest annual removal of nutrients from the wastewater was by the Tifton 85 bermuda grass in 2006 where the floating vegetation removed 690 and 250 kg ha-1 N and P in three cuttings of the vegetation. The fall panicum had the greatest annual K removal, where in 2007 three cuttings removed 780 kg ha-1. The weeds removed lower amounts of N, P, and K (approximately 300, 100, and 300 kg ha-1, respectively) in two cuttings in 2008. The study showed that plant species exist which can grow and thrive on anaerobic wastewater lagoons on floating platforms for at least two years while removing N, P, and K from the wastewater.