Project Number: 6206-13610-006-31
Project Type: Reimbursable

Start Date: Jun 01, 2008
End Date: Jan 31, 2011

Objective:
(1) Assess the environmental impacts of land-applying different rates of municipal biosolids on the production of forage and biofuel grasses and on water quality at Austin Water Utility's Hornsby Bend Municipal Biosolid Recycling Facility. (2) Identify and quantify the composition, concentration, and distribution of nutrients (carbon, nitrogen, phosphorus), micronutrients (trace metals), and endocrine disrupting compounds (EDCs) in biosolids, soils, waters, and plants. (3) Measure the potential mobility of nutrients, micronutrients, and EDCs in surface run-off and in water infiltrating through the soil profile using rainfall simulations in the field. (4) Use empirical field data to develop and test new model components for SWAT (phosphorus, EDCs) to further validate and improve model code. (5) Provide risk assessment to the City of Austin regarding the potential watershed impacts of Austin's municipal waste recycling program.

Approach:
We will conduct a broad survey of the Hornsby Bend site to assess the presence and concentrations of nutrients, micronutrients, and EDCs in biosolids, soils, waters, and plants. Ten-meter-wide strips of switchgrass will be established within the existing forage production system (coastal bermudagrass) receiving Class B biosolid applications. Rainfall simulations will be conducted in forage production plots and in biofuel production plots to quantify the movement of nutrients, micronutrients, and EDCs in surface run-off and in water infiltrating the soil profile. Crop productivity and soil microbial activity will also be measured across different biosolid application rates (0, 10, 20, and 30 dry tons/acre/year).