HR: 0800h
AN: H31B-1291    [Abstracts]
TI: Phosphorus Removal From Milkhouse Wastewater and Barnyard Runoff With Fly ash Amendments in Vegetative Filter Strips
AU: * Giri, S
EM: skg29@cornell.edu
AF: Cornell University, 122 Riley Robb Hall, Ithaca, NY 14853 United States
AU: Richards, B K
EM: bkr2@cornell.edu
AF: Cornell University, 122 Riley Robb Hall, Ithaca, NY 14853 United States
AU: Geohring, L D
EM: ldg5@cornell.edu
AF: Cornell University, 122 Riley Robb Hall, Ithaca, NY 14853 United States
AU: Steenhuis, T S
EM: tss1@cornell.edu
AF: Cornell University, 122 Riley Robb Hall, Ithaca, NY 14853 United States
AB: Vegetative filter strips (VFS) are commonly used to reduce agricultural pollutants such as phosphorus (P) present in milkhouse wastewater and barnyard runoff. Although VFS can sometimes efficiently remove P, water flow and P sorption in a VFS used for treating milkhouse wastewater and barnyard runoff were found to be erratic due to preferential flow and reduced soil infiltration capacity. Several possible amendments were tested for P immobilization potential in the laboratory, including wollastonite (calcium metasilicate) and fly ash from a coal-fired power plant. Fly ash demonstrated superior P immobilization potential, with a Langmuir adsorption isotherm capacity of 10 mg g.-1. Fly ash was placed in the wastewater holding tank and in flow channels of an actual VFS, resulting in reduction of test well water ortho-P to ug L-1 (ppb) levels. Fly ash was shown to act in three ways: P adsorption, precipitation of P as Apatite, and co-precipitation of P during hydrolysis of Fe and Al. However, during summer P concentrations in observation wells was observed to be much higher than the influent wastewater in the VFS, particularly near the preferential flow path. Measurements of dissolved organic carbon (DOC), iron and total phosphorus indicate enhanced microbial activities during summer. As a result, anaerobic biodegradation of organic matter plays a great role in releasing P, Fe and Mn from adsorbed sites. It is believed that certain components of DOC (such as hydrophilic, hydrophobic and neutrals) are formed during anaerobic biodegradation of organic matter present in water and the VFS. These DOC components may interact with iron, aluminum, manganese, calcium etc. present in soil resulting in the concomitant release of elements together with adsorbed P. A practical management approach to reducing P during summer may involve relocating the preferred wastewater flowpaths in the VFS, as well as fresh applications of fly ash to the new flowpaths in order to avoid the release of adsorbed P by microbial processes.
DE: 0409 Bioavailability: chemical speciation and complexation
SC: Hydrology [H]
MN: Fall Meeting 2005