Year Established: 2014 Start Date: 2014-03-01 End Date: 2015-02-28
Total Federal Funds: $27,500 Total Non-Federal Funds: $55,000
Principal Investigators: Zhenqing Shi, Markus Flury, James Harsh
Abstract: Stormwater is a major source of toxic metals and nutrient pollutants carried into the Puget Sound. The application of Low Impact Development (LID) infrastructure for stormwater treatment, particularly through bioretention systems, is increasing in Washington State. Although traditional compost used in bioretention systems improves retention of toxic metals, it can contribute to nutrient export as the compost decomposes. Therefore, it is important to develop new generations of bioretention materials which are capable of sequestering nutrient pollutants. Fe-enhanced compost is a promising new bioretention material. Based on preliminary laboratory tests, Fe-compost is effective for removing both lead (Pb) and phosphorus (P) from water. However, the capacity and stability of Fe-compost for contaminant removal from stormwater is unknown. There are no predictive tools for the efficiency of Fe-compost for stormwater treatment and its long-term implication on stormwater quality. We propose to characterize reactive sites in Fe-compost with a suite of chemical and spectroscopic techniques. Reactive sites are of prime importance for sequestering both Pb and P. We will determine the sorption capacity of Fe-compost for both Pb and P. We will evaluate the efficiency, stability, and longevity of Fe-compost for stormwater treatment in both stirred-flow and pilot leaching experiments. Based on experimental results, we will develop mechanistic-based kinetics models for predicting stormwater quality and fate of sequestered contaminants. This research will have broad regional and national application, and immediate and beneficial use to improve the performance of bioretention filters for removing both toxic metals and nutrients from stormwater in Washington State. One Ph.D. student and one undergraduate student will be trained in this research. This work will become part of the dissertation of the Ph.D. student. We expect to publish at least one manuscript in a high impact peer-reviewed journal for this project.