Portal de Periódicos da CAPES

USE OF FLOATING VEGETATION TO REMOVE NUTRIENTS FROM SWINE LAGOON WASTEWATER

2004; Volume: 47; Issue: 6 Linguagem: Inglês

10.13031/2013.17809

2151-0059

R. K. Hubbard, G. J. Gascho, G. L. Newton,

Phosphorus and nutrient management

Methods are needed to remove nutrients contained within wastewater lagoons. Potential exists for nutrient removaldirectly from lagoons if vegetation can be grown on floating mats in the lagoon and periodically harvested and removed.Vegetative cover of lagoons may also help reduce odor problems. A study was conducted to determine the feasibility of usingfloating mats of vegetation on swine lagoon wastewater. Wastewater from the University of Georgia swine wastewater lagoonswas pumped to replicated tanks (1285 L) in which floating mats of vegetation were grown. The floating platforms were madeof PVC pipe with attached wire screen and fibrous material into which the vegetation was sprigged. Three different wetlandspecies were tested: cattail (Typha latifolia L.), soft rush (Juncus effuses), and maidencane (Panicum hematomon SchultHalifax). Full-strength wastewater, 1/2-strength wastewater, and an inorganic nutrient solution (1/4-strength Hoaglundsolution) as a control were tested. The test was conducted as a modified batch process as opposed to a continuous flow throughprocess. The modification was that every two weeks half of the volume of each tank was replaced with the appropriate solutionof full-strength wastewater, 1/2-strength wastewater, or 1/4-strength Hoaglund solution so that nutrient concentrationswould not be depleted. There were four replicate tanks of each nutrient solution for each wetland species, for a total of36 tanks. Vegetation from the floating mats was harvested periodically by removing all vegetation above 5 cm of the base ofthe floating mat. Measurements were made at each cutting of the total biomass per tank, leaf area, and nutrient content (N,P, K) of the vegetative tissue. Growth responses were quite different among the three species. The cattail had tremendousgrowth during the spring and summer months. The growth rate of the rush was slow for the first year. It then died duringsummer of 2002 at both the 1/2-strength and full-strength wastewater, indicating that this species is not suitable for growthon floating mats in swine lagoon wastewater. Total nutrient removal by both the cattail and maidencane was primarily afunction of total biomass produced. Over the length of the study, on full-strength wastewater, the cattail produced 16,511 gm-2 biomass and removed 534, 79, and 563 g m-2 of N, P, and K, respectively, while the maidencane produced 9751 g m-2of biomass and removed 323, 48, and 223 g m-2 of N, P, and K, respectively. Results from this study indicate that potentialexists for using floating platforms to grow cattail, maidencane, or possibly other yet to be identified plant species inwastewater lagoons for nutrient removal.