Biobeds help manage contaminated water

The biobed built by Farming Smarter uses a tank to hold rinsate, two stages, and a buried tank to hold the cleaned water. Plants are used in the two biobed stages to help monitor how active the herbicides are that are being broken down in the biobeds.  |  Farming Smarter photo

Micro-organisms in the biobed’s soil break down the chemicals and make water safe to discharge into the environment

Contaminated water from rinsing a pesticide container, called rinsate, is a problem on some farms.

“I know stories where guys have been cleaning their sprayers out on a gravel pad for years and they don’t have any problem until there’s a big rainstorm, where you get six inches and then everything that has collected there over the years bleaches out and kills out your grass,” said Ken Coles, executive director of Farming Smarter.

Farming Smarter is an applied research group that works in the agricultural industry in southern Alberta, and it built a biobed to handle farm rinsate.

“As public pressures continue to increase regarding agriculture and its impact on the environment. This is just a great good news story. It’s not that hard to do and it can be used as a tool for both increasing the safety of chemical use on farms but also a really great public social licence story,” Coles said.

“In Europe where those regulations are much tighter you see a lot more biobeds. We’re not quite as restricted here in Canada, but I think there will be a time when we will be and you want to be ahead of the game.”

He said they use the biobed to handle the pesticide rinsate, as well as other unusable pesticide, including when a tank is mixed but the weather turns and the active ingredients are no longer viable by the time a spray window opens up.

“The biobed concept isn’t new. It basically uses biological metabolization of the chemical ingredients into inert forms. So they usually use a mix of soil and compost straw and you collect all of your rinsate and then slowly run it through these biobeds,” Coles said.

The micro-organisms in the biobed’s soil breakdown the chemicals and make the water safe to discharge into the environment.

The biobed Farming Smarter built has two stages, as well as two holding tanks.

“The first stage does most of the work, it’s probably in that 90 percent-plus range done in the first one. Once it’s through the second one you’ve basically got 99 percent clean water,” Coles said.

Farming Smarter relied on Agriculture Canada’s manual on biobed construction and Claudia Sheedy research, but it also made a few changes and were able to build their bed for less than $5,000.

Old pieces of concrete were pulled out of a junk pile for the pad, and the tops of cheap tanks were cut off for the two biobed stages.

The initial holding tank should be large enough to hold a year’s worth of rinsate, which is gradually moved with drip tape to the first biofilter stage.

Farming Smarter also buried a holding tank for the cleaned water that is used to water shelterbelts at the farm.

Coles said Farming Smarter promotes the use of biobeds because it’s a good practice, and that if producers would like to learn more about its biobed they can watch a virtual tour available on the research group’s website:

Application expert Tom Wolf helped bring the biobed concept to Canada from Europe in the early 2000s, and he said farmyard design should include the ability to safely and effectively manage all agricultural materials, including pesticides.

“Do we dump our waste engine oil after an oil change? What do we do with that? We deal with it properly. It’s just that there are some things where we haven’t really scrutinized our actions because we think it’s probably OK,” Wolf said.

However, he said farmers should closely scrutinize all of their production strategies and that a good thought experiment is to pretend you’re explaining to someone from Environment Canada how you’re dealing with rinsate.

“What would your answer be in, would you be proud of the answer?” Wolf said.

“It’s accepted practice but not really talked about that when we change over products there’s often a small remnant and, not everyone does it, but a lot of people just dump it on the ground because what else are you going to do? You can either dump it on the ground or you can spend an hour diluting it. If it’s a good spray day time is of the essence so it kind of forces people into situations that we don’t think are good for the industry.”

He said biobeds work best in situations where there is a central place that’s commonly used to fill and clean the sprayer, including some farms, municipalities with weed control programs and golf courses.

However, many farms are not able to return to a central location every time they switch over chemicals, and Wolf said biobeds are not the best solution to managing rinsate in this situation.

A better solution is to not have any rinsate that has to be managed in the first place, which is possible with improved clean-out designs for sprayers.

For instance, Wolf said sprayers need to be able to flush their booms easier, perform a clean out while driving, and have very little fluid left over after the tank is pumped empty.

“The two main things that were advocating for have been continuous cleaning, which is basically installing a second dedicated clean water pump on your sprayer. So that it you can spray and clean simultaneously — spray with your solution pump and clean out with your clean water pump and spray it out on the field where the material belongs, not while stationary.”

The other innovation Wolf would like to see as a standard sprayer feature is recirculating booms that can reduce the amount of material sprayed while stationary when the booms are being primed or flushed.

“Those two simple innovations can eliminate a very significant amount of material we dumped on the ground,” Wolf said.

“Many of the European sprayers have this, and that’s one of the one of the reasons why they’re actually an attractive option for a lot of farmers.”

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