Water Resources Research Act Program

Details for Project ID 2017SC106B

Phosphorus removal from nutrient enriched agricultural runoff water

Institute: South Carolina
Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $28,294 Total Non-Federal Funds: $56,335

Principal Investigators: Sarah White, John Majsztrik

Project Summary: Increased levels of nutrients in surface waters can lead to eutrophication. Most freshwater streams are phosphorus (P) limited, so the addition of P from anthropogenic sources (manure, fertilizers, wastewater etc.) can lead to algal blooms, fish kills, and other types of environmental degradation. In particular, operations growing specialty crops in containers use intensive production practices that can release relatively large quantities of nutrients into surface and groundwater. Nitrogen (N), P and potassium (K) are the major components of most fertilizers. Plants require more N and K than P, although they are typically applied at a similar ratio (i.e. 20-20-20), which can lead to relatively large amounts of P leaching from a container. Moderately lower P uptake rates in plants also make it more difficult to remove P from natural aquatic systems. Capturing P before it leaves an operation is beneficial for the environment, but may also prove beneficial for the grower if a process could be developed to recycle P within an operation. This proposed project is the first step in closing the loop for P recycling in specialty crop operations. A number of substrates have been characterized with regard to their capacity to bind and remove P from water; these include iron oxides, calcined clays, biochar, and activated carbon. To evaluate the feasibility of reducing P runoff from specialty crop operations, we propose installing pilot-scale filtration troughs at a grower operation in South Carolina to quantify field-scale removal efficiency of various types of binding substrates. Specifically, we will characterize the P-sorption capacity of both calcined clay and iron oxide sand in a flow through system installed at a collaborating grower facility. The system will consist of a large trough filled with the P-binding substrate to be tested, a pump to load irrigation runoff water into the trough, and a pipe system to return the water back to the operations water supply. Water samples will be collected weekly for three months when irrigation and fertilizer are applied by the grower. Samples will be analyzed at the Clemson Agricultural Service Laboratory for both initial and post-treatment water P concentrations. At the end of the experiment, the substrate will be also be analyzed for the amount of P recovered in the substrate. The objective of this study is to characterize P removal from specialty crop runoff using a pilot scale filtration system. Data from this study will then be used to determine if P recycling can occur at specialty crops producer facilities and to determine the adaptability of these filtration systems for use to remediate P from runoff from other applications (e.g., row crop agriculture, wastewater treatment). Future studies will determine the feasibility of replacing some or all of the P typically applied as fertilizer using the tested P-bound substrate