Worm Composting and Brewery Waste

Here is a question from Geoff:

I’m starting a batch of homebrew and had a question about
the cheesecloth and grains I used. In your opinion, can I add these
items to my worm bin?

Hi Geoff,
This is a great question, and something I’m sure a lot of other homebrewing vermicomposters have wondered about as well. If you asked me this back when I was initially learning as much as I could about vermicomposting I likely would have said “ABSOLUTELY – Go Nuts!!” (or something equally as enthusiastic – haha) because I’ve read that spent brewery waste can be a great vermicomposting ‘food’. Vermicomposting expert, Dr. Clive Edwards says this about the material:

This needs no modification in terms of moisture content to grow earthworms. Worms can process it very quickly and grow and multiply rapidly in it” (Edwards and Bohlen, 1996; p.247)

Based on this glowing recommendation, I was very excited when I was able to secure a quantity of this material from a local brewery a number of years ago. I was a teaching assistant for a university soil science course at the time, and was setting up worm composting experiment to help students determine the vermicomposting potential of various ‘foods’. I figured the brewery waste treatment would end up as one of the most successful of the bunch – interestingly enough, it ended up being quite the opposite.

We found that even when it was mixed well with bedding materials (thus helping with aeration), it still became a nasty stinky mess, and the worms didn’t seem to want anything to do with it. Over time I’m sure they eventually consumed it (it’s all a bit hazy looking back now), but it certainly wasn’t processed “very quickly”, nor did the worms “grow and multiply rapidly in it”.

I am sure not all brewing waste is created equal – and this likely explains how our results with it could end up so drastically different than those upon which Dr. Edwards was basing his assertion. I am certainly NOT trying to discourage anyone from testing this stuff out – that’s for sure!

With any sort of wet, starchy sludge, I would say that a fair degree of caution is warranted – particularly in smaller, enclosed plastic bins. I’m sure this stuff would have worked much better out in my big backyard bin or trenches since there is much better air flow, and much more habitat for the worms to hide out in. These types of materials can create a stinking anaerobic mess very quickly, literally fermenting in your bin and releasing alcohols etc. You may see a major increase in white worms and white mites as well since they tend to thrive in wet, acidic environments.

You never know though – perhaps your particular mix of spent grains (along with the cheesecloth) will be totally fine. Try it out in moderation at first and see how the worms respond!

Just my 2 cents worth!

Edwards, C.A. and P.J. Bohlen. 1996. The biology and ecology of earthworms (3rd Edition). Chapman & Hall, London, 426pp.

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    • John
    • December 1, 2009

    I’ve mentioned before that I tried to add spent brew mash to my worm bin but that it overheated. Fortunately, I limited the amount I put in and after the hot-spot cooled, the worms seemed to enjoy it.

    I’ve had better success putting in my compost pile. I’ll add six gallons of the grain to the hot side of my pile (roughly a 4′ cube) and the temperature will go from 100-110 F to 140-160 F in just a few days.

    Lately, I have been incorporating the “Bently Trench” (8^D) method, limited to grains, in my wintering garden. I dig out the topsoil, loosen the subsoil, pour in the grain and cover it with the topsoil. After about two months, the grain area is loaded with fat earthworms which, I assume, are tunneling through the soil and subsoil, carrying nutrients far and wide. I haven’t planted in these areas yet but will in the spring and I am eager to see the results.

    John in Huntington Beach, CA

    • Bentley
    • December 1, 2009

    Hi John,
    Thanks for sharing that – very interesting!
    Sounds like brewery waste could be a great material to add to a winter worm bed (kinda sounds like you’ve had similar thoughts yourself)!

    Will definitely be interested to hear how everything is looking come spring time!

    Thanks again

    • Fred
    • July 21, 2019

    What about waste hops if you use cloths to wet and dry hop?

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