Latest / The Illinois Nutrient Loss Reduction Podcast / Episode 03 | Bioreactors: How to Chip Away at Nitrogen Runoff
Transcript
- Episode 03 | Bioreactors: How to Chip Away at Nitrogen Runoff 00:00:06:13 - 00:00:28:26 Todd Gleason This is the Illinois Nutrient Loss Reduction Podcast, episode three how to chip away at nitrogen runoff. I'm University of Illinois Extension's Todd Gleason. We're now joined by Laura Christianson, a member of the crop sciences department here on the U. Of campus in Urbana-Champaign. She's been working with bioreactors. I asked her just exactly what one might be. 00:00:28:28 - 00:00:42:22 Laura Christianson A bioreactor, sometimes known as a denitrifying bioreactor or sometimes a woodchip bioreactor, is most simply described as a trench filled with woodchips that you route your tile drainage through. 00:00:42:24 - 00:01:12:06 Laura Christianson Now, inside this trench on the woodchips, there is good natural bacteria called denitrfying bacteria, that are able to convert the nitrate in the water as the water flows by them to harmless nitrogen gas. These little denitrifying bacteria, the process they're doing is actually the process of denitrification and denitrification as a natural part of the nitrogen cycle that happens in our soils all around us every day. 00:01:12:08 - 00:01:36:20 Laura Christianson So inside a bioreactor we're providing these little denitrifying, these natural bacteria, an extra food source because we're giving them extra carbon in the woodchips. Because these bacteria are the ones cleaning the water, cleaning the nitrate out of the water. It's called a biological process or a biological water cleaning process. And that's in fact where we get the name bio reactor. 00:01:36:22 - 00:01:55:26 Todd Gleason A couple of things about the bioreactor, because I've seen them put in, they're usually right before the exit of the tile into whatever drainage system it's going to. So by about the time it comes out at the at the end, why do we put it there and does it not back up everything into the rest of the field? 00:01:56:00 - 00:02:19:01 Laura Christianson No. So that's a good that's a good point. Bioreactors are considered an edge of field practice. That's how we talk about them, because they typically are at the edge of field by the tile outlet. However, bioreactors can also be somewhat in the middle of a tile system. If you have a main, linking two fields together, you could put a bioreactor, in kind of a grass grass way or a driveway. 00:02:19:04 - 00:02:46:12 Laura Christianson So they don't necessarily have to be right by the outlet. But we do call them an edge of field practice. Now, an important part of the design so that we don't back up tile drainage water is a bypass flow pipe. So every bioreactor has a bypass flow pipe as a part of the design. So that during times of the year when we have a lot of drainage water occurring, like in the spring or after a big rainfall event, we don't want to back that drainage water up in the field. 00:02:46:12 - 00:03:09:24 Laura Christianson So this bypass flow pipe allows some of the water to bypass the bioreactor. For from a drainage perspective, this is really important, again, because we don't want to reduce drainage capacity in the field. Tile drainage systems are expensive and important. And so that's an important part of the design. But of course from a water quality perspective, any water that bypasses the bioreactor doesn't get treated. 00:03:09:26 - 00:03:22:25 Laura Christianson And so with our research we're looking at ways to change the design of the bioreactor so that we're treating as much water as possible in the bioreactor even during those high flow times. But we also know that we're not backing up drainage water. 00:03:22:25 - 00:03:29:12 Todd Gleason How is a bioreactor made, and by that I mean what medium do you put in it and how does that work? 00:03:29:14 - 00:03:51:20 Laura Christianson We always recommend woodchips. That's the standard medium or fill material that we put in a bioreactor. Again, it comes back to the organic carbon. We just want to have organic carbon. That's the food for these denitrifying bacteria. So like you said, you could use anything that has organic carbon in it. Corn cobs, walnut shells, newspaper. 00:03:51:24 - 00:04:15:23 Laura Christianson Lots of people have tried lots of different things, but we've settled on wood chips because, around the world, you can get a fairly consistent wood chip product. So when I talk with my colleagues in Australia or Europe, we can talk about wood chips and all be fairly consistent with what we're talking about. Now, one of the the common questions about wood chips are all, does the kind of wood chip matter? 00:04:15:23 - 00:04:36:01 Laura Christianson That's one of the most common questions we get. And the answer to that is is yes and no. Hard wood versus soft wood. Wood chips perform about the same in terms of nitrate removal. So we're not real picky on if you're using a hard wood chip or a soft wood chip. What does matter is the size and the shape of the chip. 00:04:36:06 - 00:05:10:27 Laura Christianson We're looking very much for a wood chip, not mulch, not sawdust, not shredded woody material. Not wood chips with a bunch of twigs or leaves. We very much want what would commonly be called a playground chip, very squarish and shape, and something between generally half an inch up to maybe 2 or 3in in size. There is an additional nuance there with the wood chips in the NRCs design standard, you can't use cedar chips or any real, real kind of dark colored chip like a cedar. 00:05:10:27 - 00:05:35:19 Laura Christianson And you can't use more than 50% oak chips here in Illinois. Now, that's in the NRCs design standard, because NRCs is concerned about those kinds of chips leaching a lot of tannins out. Oak is known to be a very high tannin wood, just naturally. And so we don't want to leach tannic acid out of our wood chips and create actually create a water quality problem. 00:05:35:21 - 00:05:55:27 Laura Christianson And so right now with our research, we're working hand in hand with the USDA, NRCs to evaluate if we were to use oak chips, how much tannic acid actually does leach out of the chips, and how much of a problem would it really be? And so that's a good example of our research. Really trying to inform what's happening in the field. 00:05:55:29 - 00:06:13:19 Todd Gleason If NRCs is involved, the Natural Resources Conservation Service, clearly there is there are some design parameters here. And we're not just digging a pit and dumping chips in and then routing the water through it. Is it covered or is there are there design parameters around it? 00:06:13:26 - 00:06:25:08 Laura Christianson The USDA, NRCs, Natural Resources Conservation Service, as you mentioned, does have a federal conservation practice standard that gives guidance on how to design these. 00:06:25:08 - 00:06:49:20 Laura Christianson Now, there's, criteria about how much flow you need to try to treat from a certain drainage system, and other criteria like that. Obviously we talked about the woodchips. Yep. So there is there is federal design guidance. But an exciting thing is that the NRCs has been fairly flexible to allow us to continue research so that we can hopefully inform, any revisions to that design guidance. 00:06:49:23 - 00:06:51:05 Todd Gleason Are these efficient? Do they work? 00:06:51:09 - 00:07:10:13 Laura Christianson Yeah. Bioreactors, I consider to be one of our most effective practices. Again, it's an edge of field practice specifically targeting tile drainage. And so it's not changing what you're doing in the field. It's there at the edge of the field catching the nitrate. Here in Illinois, we rate bioreactors at 25% effective. 00:07:10:13 - 00:07:28:07 Laura Christianson So in other words, a bioreactor would remove about a quarter of the nitrate that would otherwise go downstream. I feel like that number is a little low, which is where our research comes in. We want bioreactors to be working more efficiently. So that it can be more cost effective, and be a relatively farmer friendly practice. 00:07:28:10 - 00:07:29:07 Todd Gleason Hey, thanks so much. 00:07:29:09 - 00:07:30:16 Laura Christianson Thank you. Todd. 00:07:30:18 - 00:07:54:09 Todd Gleason Laura Christianson works for the Department of Crop Sciences here on the Urbana-Champaign campus of the University of Illinois. Her research has been focusing on bioreactors and how they can help to remove the nutrient load in tile lines at the edge of a field. If you're interested in this practice, you can contact University of Illinois Extension to find out more details about how to implement a bio reactor. 00:07:54:11 - 00:08:00:16 Todd Gleason Haley Haverback is here. She tells us there is funding available to help offset the construction cost. 00:08:00:16 - 00:08:18:20 Haley Haverback One of the options would be the environmental quality Incentives Program or EQIP, through NRCs. And so for FY 2018, payment rates will vary between 35 and $45 per cubic yard of carbon, depending on the type of wood chip bioreactor being installed. 00:08:18:27 - 00:08:46:10 Haley Haverback So specifically, that depends on whether the trench is capped with a soil cover. And then another funding alternative would be the partners for conservation PFC program, run through the Illinois Department of AG, through the local soil and water conservation districts, and under the State cost share, the soil water conservation districts will cover about 75% of the cost, or around $47 per cubic yard. 00:08:46:12 - 00:09:03:23 Haley Haverback And then also my advice would be anybody, if you were found any of this information really compelling and you want to look into putting one of these practices on your own farm, just head over to the local Soil and Water Conservation District, and they can help you out with different funding options and maybe even some local watershed programs. 00:09:03:27 - 00:09:11:12 Todd Gleason Haley Haverback is with the University of Illinois Extension, you've been listening to the Illinois Nutrient Loss Reduction podcast. I'm Todd Gleason.