Use of Filters in Drainage Control Structures to Reduce the Risk Associated with Manure Application on Tile-Drained Fields
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For more: http://www.extension.org/67605 In livestock producing areas, animal manure is often applied to cropland to enhance soil fertility. Guidelines have been developed for manure application on fields underlain by subsurface (tile) drainage systems. Some of these guidelines, such as avoiding manure application if rain is predicted and not applying manure over a flowing tile, though effective, involve some level of risk. We believe that the level of risk can be reduced by filtering contaminants from the water leaving the drains. The control structures recommended for use with drainage systems underlying fields to which manure is applied, provide ready-made receptacles for filters. In this report we discuss the development and testing of a filter to remove contaminants from lagoon effluent.
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Use of Filters in Drainage Control Structures to Reduce the Risk Associated with Manure Application on Tile-Drained Fields
- 1. Filters in Tile Drainage Systems to Reduce Risk of Surface Water Contamination Stephanie Herbstritt, Annie Kwedar Dr. Richard Cooke University of Illinois at Urbana-Champaign Agricultural and Biological Engineering Department
- 2. problem | design | methods | results | conclusions Photo thanks to University of Kentucky Photo thanks to University of Minnesota Photo thanks to University of Illinois Liquid Manure Application Injection Manure Application
- 3. problem | design | methods | results | conclusions
- 4. problem | design | methods | results | conclusions
- 5. problem | design | methods | results | conclusions Thanks to David et. all
- 6. problem | design | methods | results | conclusions Thanks to David et. all
- 7. problem | design | methods | results | conclusions
- 8. Drainage control structures and inline tile stops are recommended control practices to reduce the risk of a discharge. The use of inflow and outflow structures for drainage water management practices, provide ready-made receptacles for filters. problem | design | methods | results | conclusions Thanks to Agri Drain
- 9. problem | design | methods | results | conclusions
- 10. problem | design | methods | results | conclusions
- 11. problem | design | methods | results | conclusions
- 12. problem | design | methods | results | conclusions
- 13. Capacity Control Structure 5’ Soil Backfill Woodchips Trench bottom at the tile invert level Length/width dependent on contributing area Diversion Structure Section of perforated tile problem | design | methods | results | conclusions
- 14. Combination structure 5’ Soil backfill Non-perforated tile Perforated tile Phosphorus removal chamber problem | design | methods | results | conclusions
- 15. Solid pipe Solid pipe Perforated pipePerforated pipe Plastic Liner
- 16. problem | design | methods | results | conclusions • Cost? • Lifetime? • Space requirement?
- 17. Acknowledgements Richard Cooke Associate Professor University of Illinois Agricultural and Biological Engineering Department Laura Pepple Livestock Extension Specialist Julie Honegger University of Illinois Agricultural and Biological Engineering Department Undergraduate Assistant
- 18. Thank you!
Notes de l'éditeur
- Hello I’m Stephanie Herbstritt, a graduate student at the University of Illinois and I’m Annie Kwedar, a senior undergraduate and we’re going to discuss a project that we’re working on with Richard Cooke, a faculty member in the Ag. Engineering department at the U of I that deals with implementing filters into tile drained systems to reduce the risk of pollutants from entering surface waters.
- So we’re going to start off with the problems that are driving this project. Liquid animal manure is a valuable source of nutrients and organic matter for crop production and in livestock producing areas may be applied by a variety of methods including spray irrigation, land surface spreading, and shallow subsurface injection. Because of its relatively low nutrient concentration, liquid animal manure may be applied at relatively high volumes, but it is generally recommended that it not be applied at rates that exceed the soil infiltration rate, nor exceed the amount needed to bring the soil to field water holding capacity. But even when similar guidelines are followed, liquid manure discharges from tile drains has been reported in soils with subsurface drainage due to macropore flow.
- Tile drains during application have been linked to contamination of the effluent with nutrients, organic matter, bacteria, antibiotics. These findings are not universal, however, as liquid animal manures can be applied without any detectable adverse effects on water quality. But the fact that liquid manure can be safely applied in some instances and in other instances find its way through preferential flow paths and into subsurface tile drains and then to surface waters and pollute them suggests a complex system that needs to be managed.
- In our soil and water group at the U of I, our primary focus is with nutrients. Bacteria and antibiotics are certainly a concern for the aquatic life and the people who rely on surface water for drinking water but our focus is on nutrients.
- If we look at this map of the U.S., one can see the large nitrate loses from the intensively farmed upper Midwest. And of course excess nutrients is a driver for eutrophic waters and the hypoxic zone that we see in the Gulf of Mexico and other coastal areas around the globe.
- This map shows you our other nutrient of concern, Phosphorous, on a kg per hectare basis entering surface waters in the Mississippi River Basin from that intensively farmed region of the Midwest. Again, the concern in combination with nitrate, is impaired water quality, leads to the formation of algae, hypoxic zones, yada, yada, yada.
- And a lot of precautions are already made when applying manure to prevent this movement from fields to surface waters. For instance, it is suggested that the application rate of liquid manure not be greater than the available water holding capacity of the soil at the time of application. It should not be applied to drained cropland if the drains are flowing. It should not be applied when rainfall is predicted, eminent or directly after an event. Fields with a history of downward movement of manure should require shallow tillage to disrupt preferential pathways (worm holes, macropores, root channels) prior to application. For clay soils, the same is true (shallow tillage may be required) as they tend to have high shrink swell capacity causing deeper cracks during dry conditions. A lot of times, subsurface drainage outlets are monitored during application and if manure laden flow occurs, effluent is captured.
- And already drainage control structures and inline tile stops are recommended control practices to reduce the risk of a discharge and we feel the use of inflow and outflow structures provide ready-made receptacles for filters and we’re investigating this proposition at the University of Illinois. So we put a picture of one of these Agri Drain structures on this slide and the idea is to turn the gates or logs into a filter for nutrients.
- So we’re currently working on a particulate filter that would effectively treat liquid manure flow that entered the tile system to reduce the risk of effluent contaminating surface water. The filter on the left is the initial prototype that when tested in our soil and water lab inhibited flow through the agri drain structure. We then designed a filter with more depth to allow for high flows and increased contact time. You can see that on the right. We’re trying to reduce head as much as possible through the filters as we want the filter to be able to handle high flows, but at the same time we’re trying to balance having a long enough contact that that tile water has with the filter so the water can be effectively treated.
- So our initial prototype was a simple activated carbon filter. And we tested this filter at our soil and water lab to determine if it can even handle flows normally seen in tile drains. We pump different flow rates through the structure and over time the water builds up on the inflow side of the structure and we measure that head and come up with a relationship between flow rate and head.
- And have started to come up with a relationship between head over time and with typical field flow rate. It’s challenging to design a filter capable of handling high flows while still allowing water to be in contact with the filter for long enough to experience increased water quality and not causing that water to back up in the structure because that would mean ponding on the field in real life.
- We’re in the process of setting up experiments in our lab and at the University of Illinois’ South Farm. We plan to run tests for a set of flow rates and retention times with a spiked influent or with a certain concentration of manure and with different filter medium materials. And then we’ll sample the effluent for nitrate to see how well the filter works at addressing nitrate removal. We’re in the process of getting field sites to perform an actual field study.
- Another piece of this project is implementing the filter into a relatively new management practice—subsurface bioreactors. This project kind of came about as an add on to bioreactors which are extensively designed, researched and implemented at Illinois. So in case you don’t know, these are used to address nitrate loss from crop land to surface waters. These are trenches filled with woodchips placed on the edge of crop fields through which nitrate-laden drainage water is passed. And through denitrification, microbial activity transform the nitrates to harmless nitrogen gas. So this is a picture of the most recent bioreactor we installed at the U of I this past fall. On the right is a diagram of the entire structure from a side view.
- You might get a better sense of it from this top view. In these systems, the diversion and capacity control structures are combined into one. Our filter would fit in the inlet and/or outlet of the control structures. Our group feels the filter could increase the effectiveness of this management practice as the bioreactor only addresses nitrate. We feel the filter could handle an unintended consequence of bioreactors—methylization of mercury—which is currently being researched in our lab group. Due to the very reducing conditions necessary for the bioreactor to work, there is a potential for sulfate reducing bacteria to convert mercury which may be naturally occurring in the soil into methylmercury which of course is a neurotoxin that bioaccumulates in fish and is harmful to aquatic life and then those higher on the food chain—humans. We also feel the filter if designed with a Phosphorus sorbing material could help turn these bioreactors into a viable option for both nitrogen and phosphorous in the unlikely case that you’re getting phosphorous in the tiles. And if this becomes the case, the phosphorous removal chamber that you see above would be replaced.
- So, this is an animation to show you how it works. Water flows in through a tile into the control structure, then is diverted through the bioreactor via this perforated pipe and then is diverted back to the control structure outlet through the perforated pipe at the end and then moved to the control structure through this solid pipe and then the water flows through the outflow tile to a drainage ditch.
- So like I said, this project started as a piece of the bioreactor, but we’re now seeing it as maybe a more cost effective alternative. As you might suspect these bioreactors are costly to install—need to excavate the trench, purchase wood chips and what not. So our smaller tile filter is certainly an alternative. We still need to do cost analysis and determine lifetime but the filter might be $50 compared to $5 grand
- Thank you for your time and we look forward to answering any questions and hearing your thoughts as we move forward with this project.