Interview with Mai Ann Healy – Biofiltro

Last month, after stumbling across a fascinating article I had shared on Facebook (several years before) about a winery using some sort of bio-filtration bed containing composting worms, I found myself completely immersed in the topic of “vermi-filtration” – with most of my attention on the work of a company called BioFiltro.

My brain nearly exploded (in a good way – haha), I wrote a blog post on the topic (see “BioFiltro – Vermicomposting Filtration Systems“), and I immediately reached out to see if I could connect with anyone from the company for a little Q&A session.

In short order, I received a very friendly email back from Mai Ann Healy, BioFiltro’s Head of Business Development, saying she would be more than happy to answer any questions that I had. It took me a little while to get my questions put together and sent in. Mai put me to shame by literally sending back her answers the very same day…and here we are!

1) Can you tell me a little about how Bio-Filtro got started?

There was a biophysicist professor at the University of Chile (Santiago, Chile) who was studying how worms could be used to break down sludge from municipal waste plants (the gunk that builds up in big ponds commonly used to treat water for towns/cities). Our co-founder, Alex Villagra, was one of his TA’s who took this idea a bit further and figured that if he could devise a way to slow water down, worms could treat wastewater as it is produced and then eliminate the need for ginormous ponds, sludge generation, intensive electricity consumption, etc all together. Alex iterated on the technology for a few years until he introduced the first commercial scale project at a rural town in Chile in 1996 and it handled about 13,000 gallons per day (GPD) for 200 – 250 people.

2) Can you tell us about some of the early (and maybe ongoing) challenges relating to this type of system?

One of the major challenges is human nature and the ability to forget about wastewater, and their wastewater systems, until it becomes a problem. Across all countries, we have to engineer systems that aptly reflect a price point that meets the amount that a client wants to pay, the amount of automation that the client needs, and the amount of automation that we want the client to have. The latter is important and crucial, as many clients want to pay the minimum, but eliminating automation requires them to be more involved in the system, which all too often doesn’t happen.

3) What are some of the specific challenges linked to working with a living organism like worms? I would think some of these wastewater sources wouldn’t be worm-friendly, and I’d also wonder about things like high temperatures (both climate influenced as well as based on the size of these beds and the rich effluent being added).

The greatest challenge at our plants are “alive” in that what comes down the drain changes by the minute, and can vary based on the operating practices in place in the production facility, town, winery, etc. You can get chemical spills, large objects, and extreme pH levels – some of which can be accidents, some intentional, and some part of the job.

Designing a system that protects living things against errors of human nature is a challenge as you have to predict the worse and build accordingly. The worms and microbes in the system require pH between 5.5 – 9.0, while wastewater from wineries, tomato processors, can be extremely acidic and then sanitation chemicals can be very basic so you get a lot of swings. We put equipment in place upstream of our worm beds that help buffer any potential “shock” and/or adjust pH.

All our systems are remotely controlled via telemetry systems which monitor flow, pH, ORP, EC, and other constituents that help us determine the health of the system and, if necessary, make changes to flow/irrigation schedules to mitigate any negative impact. Weather doesn’t impact our system because ultimately we are a composting facility, so the internal temperature of our system is always the same – we have systems in Central WA that experience -15 degrees but once you poke through the surface, steam will come out.

In extreme heat, as in the Atacama Desert where we service remote mining towns, we put our systems under shade structures. Influent water temperatures are considered to ensure that the pipes and pumps don’t freeze or burst.

4) Have you used any species other than Red Worms in these beds?

Not specifically, there are usually a few others but the California Red Worm is the prime star.

5) I first heard about Bio-Filtro thanks to an article about a California Winery that was planning to install a system (I believe the first California winery to do so at the time). Have more wineries followed since then? Is this an approach that works well for that type of wastewater?

Extremely well for wineries, we are in 4 wineries currently with 5 more planned for installation. Here is a video for a case study on a Napa winery.

Wineries and seasonal processors, ie facilities that vary in volume and wastewater strength throughout the year, are challenging to treat for any wastewater treatment technology (WWT) as some processors, like tomatoes, only produce for 3 months of a year and then shut down completely so there is no water/food for the WWT systems.

Wineries meanwhile, will have the largest volume and highest strength (aka dirtiest) water during harvest in late summer/early fall, and will have next to no discharge during the winter months. A lot of WWT systems like steady volume and to “eat” the “same food” every day, but luckily for us, worms and microbes love to snack on anything and everything, so if a processor is processing strawberries one day and peaches the next, the worms love it.

If a winery is doing white wine and red wine the next, worms love it, etc. Wineries also love our system because it’s energy efficient, chemical free (so good story for sustainability) and then you produce worm castings which can be reapplied to the vineyard. Here’s a video that Fetzer Winery did.

6) I was really fascinated to see mention of a human waste processing system in Antarctica. Can you tell us about this?

It’s for the Eduardo Frei Air Force Base which also has a school, supermarket, hospital, and some research facilities for France. That one is under a roof given the extreme winds and snow that occurs on the waterfront.

[Bentley’s Note: You can learn more about the potential of these types of systems via BioFiltro’s “Sanitary Wastes” page]

7) One massive area of potential I see for these systems is handling liquid livestock manures (and I saw a really interesting video about a NZ farm doing this). Has there been any interest from dairy/swine farmers in U.S.A?

Royal Dairy in Royal City, WA won the US Outstanding Dairy Award for Sustainability. for use of our system. He was previously land applying over 4,000 acres, most of which required transporting the wastewater in trucks to offsite locations, and now only needs 400 acres to properly dispose. He averages 80%+ in contaminant removal and UC Davis did a study that shows how our system reduces GHG emissions by 91%+ when compared to the emissions of a dairy lagoon. You can find that study and a short video about Royal on our “Dairies” page [Bentley’s Note: I have included the video below as well]. We also have a dairy in Central California that was done with a USDA NRCS grant.

8) Any other exciting projects/new developments on the horizon, or anything else you’d like to share with our readers?

We provide a WWT for a highway exchange plaza (aka rest stop where you have a Best Western, Mcdonalds, Subway, supermarket, etc) along Interstate 5; provide WWT for one of the Travel and Leisure’s World Best Hotels in Patagonia, EcoCamp, which is a glamping resort and we built our system to mimic the same geodome design as the rest of the hotel. And another system, Our largest system handles 2 million gallons per day!


Absolutely amazing stuff! Thanks so much to Mai Ann for taking the time to answer my questions. I am very excited to see where BioFiltro (and vermi-filtration in general) is headed in the years ahead!

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    • Andy Loy
    • June 22, 2019

    Nice interview. I just wonder how the vermicompost is harvest from the BioFiltro system. What species of bacteria actual breaks down the waste water? In the mushroom world, straw that is inoculated with oyster spawn is another way to clean waste water in ponds and streams on a test scale. This method is call mycoremediation. Probably someday, mycoremediation, redworms, and vermifilteration will be one unit for waste waster treatment.

    • Mai Ann Healy
    • June 26, 2019

    Hi! I wanted to respond to Andy’s question – unlike vermicomposting where worms push their castings to the bottom, the worms in our systems push their castings up to the system surface. Then, all we have to do is skim the system surface to remove the castings. If it’s a small system, this task can be done manually, while our larger facilities are built so that long arm excavators can be used to remove the casting layer from the top of the facility. Castings are placed in a dump truck that follows the excavator and can be then shipped off to its final destination, be it the client’s fields or elsewhere. We just finished harvesting one plant that yielded 2,000 cubic yards of castings soooo worm poop for the win! As for microbes, the dominant specie depends on what wastewater contaminant we are trying to remove, UC Davis did a study (you can find it on our dairy page) where they highlighted all the bacteria present in one of our dairy facilities where we need to target nitrogen removal. If they were to do a study for our system in a different industry, the species would be completely different.

    • Bentley
    • August 12, 2019

    Very sorry Mai & Andy – I literally just realized that Mai’s comment hand’t yet been approved! 🙁

    • Andy
    • August 13, 2019

    Thank you, Mai. Skim the castings from the top. Now I understand how your system works.

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