Solving Eco-Challenge 1: Nitrate Capture System

Challenge Summary

 Concepts for systems to capture, concentrate, or treat nitrates from agricultural field drainage are required. Tile drains (submerged porous pipes) are a cost effective and efficient way to improve drainage of agricultural land. Unfortunately, they also provide an efficient route for fertilizers (primarily nitrates) to pollute rivers, lakes, drinking water supplies and ecosystems downstream. Nitrate capture and concentration or treatment (release as N₂ gas) systems are required that would be amenable for application in agricultural settings and that are compatible with tile drainage systems.

About Our Solvers

Our first Solver Patrick Fuller is a graduate student at Northwestern University in Chicago. Patrick's solution suggests to use algae to consume pollutants in drainage streams, producing nitrate-rich biomass recoverable for use as fertilizer.
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Mario Rosato, our second Solver, who hails from Spain, proposes combining controlled drain and sub-irrigation system (CDS) with a complementary cash crop (bamboo) to absorb nitrogen.
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The third solution is by Doug Hamilton from Vancouver, Washington. Doug suggests placing vertical metal dams at each end of existing drainage ditches to convert them into retention ponds. The water and residual nitrate captured in the ponds could then be reapplied into the fields.
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The Selection Process

This challenge was posted on May 26 and by the close of the challenge period on July 13, more than 240 InnoCentive “Solvers” had registered to view the challenge and 42 viable submissions were received. EDF assembled a Working Review Committee – composed of staff, farm industry reps and consultants -- to assess and score these submissions and ultimately narrow the 42 submissions down to 3 finalists (this includes two individual, yet related submissions, from two different Solvers, that the committee decided to combine into 1 concept). All the submissions were assessed according to the following technical requirements:  

1. Compatible with existing tile drain systems
2. Efficient (>40%) capture of nitrates from tile drain effluents
3. Cost less than establishing a wetland or reduces the amount of land removed from production to generate the same benefits
4. Low maintenance and robust
5. Remains viable during periods without fresh drainage water (dry weather)
6. Captured nitrates are amenable to use by growers (Essentially, this would create a closed-loop systems in which farmers could reuse fertilizer.)