Assessment of Copper Removal From Highway Storm Water Runoff Using Fish Bone Meal
||Oregon State University|
|Start Date for ODOT:
|Completion Date for ODOT:
The overarching goal of this project is to identify an efficient and cost effective means of remediating copper in highway stormwater runoff. Specific research questions include:
1. What is the “state of science” regarding removal of metals (copper in particular) from highway stormwater runoff?
2. Is fish bone apatite (or some other identified alternative) a viable technology that could be incorporated into stormwater BMPs?
3. How do alternative technologies compare with existing best available technologies such as compost?
4. What are the efficiencies and mechanisms of copper removal by alternative technologies?
5. How can alternative technologies be integrated into currently accepted stormwater management strategies?
6. What are the costs and benefits of alternative technologies in terms of water quality and construction and maintenance costs? OVERVIEW:
Highway stormwater runoff is one source of copper into the surface waters of Oregon, many of which are home to threatened and endangered salmonid species. The ODOT Best Management Practices (BMPs) with the most robust performance are bioslopes and bioswales, especially with regard to metals removal. They are implemented wherever practicable. Bioslopes use a media mix of aggregate, dolomite, perlite and gypsum to reduce dissolved copper from highway runoff through microbiological activity and adsorption. Research at Washington DOT indicates that bioslopes are capable of reducing dissolved copper from 15-20 µg/L (typical of highway runoff) to 5-7 µg/L. Design and implementation of these types of BMPs has become an increasingly large part of transportation projects, sometimes contributing 20-25% to the overall project costs.
Even the current best available technologies are not capable of removing copper to the levels which regulators currently consider "no effect" . Copper acts as an olfactory neurotoxin in salmonids, diminishing olfactory sensitivity and detrimentally influencing behavior. In research at the National Marine Fisheries Service (NMFS) Seattle lab research, olfactory effects were seen at dissolved copper concentrations on the order of 2 µg/L above background levels (< 3 µg/L). The assumption arising from these studies is that even slight increases in copper concentrations above pre-urbanization development may cause harmful behavioral and sensory effects in salmon. Even if these extremely low levels are shown to be overly conservative, the improved efficiency of the fish bone meal will likely have benefits in the form of reduced the size (=cost) of the bioslopes and increased longevity.
Phosphate based minerals have been used in a number of instances for remediation of soil and water contaminated with heavy metals including lead, cadmium, zinc, and copper. Based on preliminary research in Region 1, the addition of fish bone meal to bioslope media mix appears to offer the potential to reduce dissolved copper to background levels (near 2 µg/L at filtration rates of 1 gpm/sq. ft. of fish bone meal media). This research proposes to characterize and quantify the extent and mechanism of copper removal by fish bone meal to determine whether the preliminary results are sustainable, reproducible, and able to be incorporated into bioslope design. PROPOSED ACTIVITIES:
The research questions listed above will be answered through the completion of four primary tasks: a detailed literature review; bench-scale testing; field testing; and data analysis and reporting. Specific tasks are outlined below. Task 1 – Literature Review.
A comprehensive literature review will be completed and provide a foundation for the proposed research, framing this study in the context of what is currently known. This task will build on the work already completed for the copper speciation project that is nearing completion. Specific topics for review will include: (1) achievable removal rates and effluent concentrations for BMPs for metals removal from highway runoff; (2) treatment technologies for metals remediation used in other applications (e.g., acid mine drainage, municipal wastewater); and (3) mechanisms of copper removal by fish bone meal, compost, and related compounds such as woody lignin and phosphate rock. Task 2 – Bench Scale Testing.
On the basis of the literature review, a short list of promising and existing technologies will be identified for further testing. At a minimum, fish bone meal and compost will be tested. Bench-scale column tests will be performed using synthetic stormwater and actual stormwater to quantify the extent to which dissolved copper can be removed from solution. Preliminary variables to be investigated include the concentration of dissolved copper, water quality parameters (pH, ionic strength, the presence of other metals, the presence of organic matter), and filtration rate. Further tests will examine the stability of the bound copper (i.e., whether or not the copper is susceptible to being released from the media) and the release of phosphate from the fish bone media. Finally, to the extent possible, research will attempt to characterize the mechanism of copper removal by the various media. Task 3 – Field Testing.
Results from the bench-scale testing will be used to design a field-scale investigation of the most promising materials. This task will consist of identification and modification of existing bioslope media filters to include the identified technologies. Field sites will be selected to allow the comparison of modified and unmodified bioslopes; each site will be set up to collect water quality (e.g., pH, redox-potential) and hydrologic (e.g., rainfall, water level) data, in addition to collecting samples for metals analysis. Performance of the BMPs will be evaluated on a storm by storm basis and throughout a storm season to quantify changes in the media and examine the mechanisms of copper removal. Task 4 – Data Analysis and Reporting.
Results will be used to develop cost curves for bioslopes with and without fish bone meal and/or compost media and evaluate the benefits and costs associated with the addition of fish bone meal to bioslopes. Furthermore, the findings will be used to produce recommendations for design of bioslopes and media component configurations as well as maintenance issue such as media lifespan. These results, along with data from the bench and field testing, will be incorporated into an ODOT research report. The findings will be published in peer-reviewed journals. ASSESSMENT OF COPPER REMOVAL FROM HIGHWAY STORMWATER RUNOFF USING FISH BONE MEAL: LABORATORY AND FIELD TESTING WORK PLAN Quarterly Reports: