Woodchip Vermicomposting

A question from Walt:

Great Website. Great Information. Thank you.
I am working on plans to build a C&D (construction and demolition)
recycling facility in the Phoenix Arizona area. Included in this waste
will be a lot of wood, (scrap 2×4 & 2×6 etc.) and the local market is
for already saturated with woodchip bedding, sawdust, mulch etc. I
need to find a new use.

One Question:

Can I chip the wood, and mix it with waste paper from construction
sites, some food waste, and dirty horse bedding (more woodchips, with
manure) to make food for the worms?

I know that my next biggest challenge will be temperature, but this
can be kept under control with shade and an automatic watering system.

This will be on a large commercial scale, and I plan to sell the worm
castings, and tea locally.

Hi Walt,
That sounds like an interesting project. While I’m not 100% sure that you will have the sort of success you are hoping for with that particular approach, I do still think there may be some potential there.

Wood wastes generally aren’t the best composting materials due to the fact that they have a very high C/N ratio, and have a structure that’s very resistant to microbial degradation. They also tend not to hold moisture all that well. Some of the other materials mentioned – namely the food waste and bedded horse manure – are great for vermicomposting, but all in all it seems as though you are going to have a mix with a pretty high C/N ratio.

As a “worm food” wood chips – even rotten wood chips – are pretty poor unfortunately, but they could still serve as a valuable bulking agent to help keep your beds oxygenated. Assuming you’ll have access to enough food waste and manure to get your C/N to a good composting range (25:1 to 30:1 or so) I’d actually recommend hot composting your mix for a while before adding it to vermicomposting beds – this should help to reduce the heating potential and just generally make it a bit more “worm friendly”. The chips themselves, along with some other resistant materials will need to be screened out at some point, but perhaps you can market this stuff as a microbially-enhanced mulch or material people can add to their own backyard composters as a bulking agent and microbial inoculant. You might also consider mixing it with more manure etc and composting/vermicomposting it a second time so as to enhance it even more.

Apart from microbial heat (generated when attempting to compost large quantities of material), you will of course also have your local climate to contend with. I would imagine that it might be quite challenging to operate a large-scale outdoor vermicomposting facility in Phoenix Arizona – but perhaps with your shade and watering systems you’ll be able to keep conditions in the beds favorable for the worms.

Hope this helps. Good luck with your project!
8)

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Comments

    • henry
    • August 10, 2011

    won’t there be an issue w. the (presumably chemically) treated lumber?

    • Ted
    • August 10, 2011

    I was thinking the same thing. Once it’s saw dust, you don’t know if theres oils, grease or pressure treated chemicals involved.

    • Gordon
    • August 11, 2011

    I suspect that chipped wood waste would be better composted by mixing with an approximately equal amount of fowl manure in a normal (commercial scale) composting process with temperature monitoring and regular turning. Moisture levels might be an issue – I only know of fresh chipped wood waste being dealt with in this way, e.g. trees cleared during power line or highway construction work.

    • John Duffy
    • August 11, 2011

    Walt,
    If you could get a good supply of grass clippings to help balance the C/N ratio and then hot compost the mixture as Bentley suggests, it just might work…Sounds like an interesting proposition. Good luck with it.

  1. A good supply of grass clippings in Phoenix? There’s not much grass down there.
    Better might be the back end of a Starbucks or see if you can get some manure from the dairy lots. I live up the hill in Flagstaff, I’d be interested to see how well this turns out. I’d love to tour the facility when it’s up and running.

    • Steve L.
    • August 11, 2011

    If I were trying to do what you say…
    * I would chip the wood as small as possible
    * Collect/receive used coffee grounds and water-rich food waste from restaurants and grocery stores/markets. (I know Burger King, and I’m sure other fast food outlets, buy their shredded lettuce in bags and has to rotate it for fresh when it gets old.)
    * If possible build your worm bins in below-grade trenches or excavated areas to take advantage of the cooler temp of the ground.
    Just some thoughts. It’d be interesting to hear of your progress.

  2. Actually, this is about the mix I use–except tree trimmings and not waste wood. It takes a bit longer for the tree mulch to break down, but when I see the white filaments in my worm beds and garden beds, I know it has been beneficial. I just use a 1/4 and 1.8 inch screen to screen it out when I get castings, then it goes back into the beds to incoculate new beds with the microbes needed for faster worm composting. I have 8X4 open beds, with a misting system…NO reproduction this summer in the many days of 100+ degrees, but we are staying alive. Anxiously ready for a cool down!

    • Bentley
    • August 16, 2011

    Thanks for chiming in, everyone! Some interesting thoughts/ideas.

    Regarding the pressure treated wood – is this something that get’s used for anything other than weather-exposed structures (fences,decks etc)?
    The key would be to get the finished compost tested for chemicals. I don’t imagine there would be enough in there to actually harm the worms (especially considering everything else that would be getting mixed in – such as horse manure etc etc).

    Anyway – hopefully Walt will keep us posted.
    8)

    • Walt
    • August 16, 2011

    Thanks for the great thoughts and ideas. I think have a design for the worm beds figured out, which will be in ground, and fully automated using an irrigation system to control the temperature. I’ve designed a lot of funky things before, and I think this will work. (I will be excited to share my results when things get going)
    Considering the wood that could be used……. most construction lumber is not treated. At least not here in the desert. In my mind, using OSB, or Plywood, will be out of the question unless it can be proven safe. (who knows what they put in that glue) Does anyone want to know an interesting fact about “treated” wood? Because of all the regulations, I am told that the treated wood that the average person would buy over the counter, to build a deck, or fence must be treated with products that are not harmful to humans. (This is not the case for power poles, or pilings driven to shore up buildings) I’ve spent some time working on some construction projects in Southern Louisiana, and any lumber used outside has to be “treated” with something, or else it rots away in a year. Sometimes the product is green, and sometimes it’s yellow. They say that you can break off a piece and chew it up without doing harm to yourself. (yet I still wouldn’t do it) So…. in the off chance I had some treated wood show up, I would feel comfortable grinding it up and feeding the worms with it, as it would be mixed and reduced by the other products. On the other hand, if I was in a wetter climate where there is more of this product being used, I may limit my use of it at some point.
    As for a small amount of contaminants like oil or grease which could possibly get mixed in…… Mother Nature has all kinds of great microbes that eat that stuff right up.
    To do some hot mixing first, I thought about using grass clippings, (of which we have an endless supply, as we do love our grass in the desert!!!!) but I’m not sure I want to risk using them. Here, in the desert, Bermuda grass is the only thing tough enough to grow in the terrible soil, and endless heat. It takes very high, and continuous heat to kill the Bermuda seeds that will be delivered with the clippings. These seeds just need a little moisture, and they will germinate anywhere, especially in nice new compost or worm castings. All the seeds have to be killed, or you cannot ever use the compost. I don’t really want to hot compost everything to the point where I know, without a doubt that all the grass seeds have been killed. This is already done here, and it really defeats the purpose of the worms.
    So, for now, pending any other fabulous ideas, I think I am going to try chipping some excess construction wood, and mixing it with some freshly cut green wood, along with some manure, to get the hot process started. Once things are breaking down nicely, I will put this in my bins and add more manure, food waste, and paper. I will keep this cool with water, re-circulating the tea through the mix several times before harvesting it.
    I know this overall process will take longer, and may be more work, but, it reduces a landfill issue, and produces Great products that can be used or sold.
    Once again, a Great website, and Thanks again for the feedback. I will stay in touch.

    • Zeb
    • August 19, 2011

    those sound like some pretty wet worms. i might suggest harvesting the castings before opening the flood gates of recirculating poo water. or have a totally separate system for the tea. also, if your main motivation for starting this project is because you have excess wood waste then it might be a good idea to build something that can work under typical operating conditions for optimum production, like in a garage with a/c, or basement, between 70 and 80 degrees, in a comercial size worm bed. if you have way extra wood waste, build another and expand your operation. if you still want to work outside in the heat, consider building enclosed, and insulated, temperature controlled houses for your worms, because they would appreciate some a/c on a hot day of 100+ just as i would on a hot day of 85+ being that i’m from Vermont and we barely see 80 in july.
    be sure that your process works on a somewhat small scale before getting too deep. good luck.

    • Adam
    • April 24, 2012

    I’m also working on starting a vermiculture system in AZ. I’ve designed my bins and plan on starting up operations later this year. I actually already have started with the worm factory 360 so I can start reproducing worms for my larger scale operation.

    • Adam
    • April 24, 2012

    I won’t disclose my design for the bins on here yet, but it will be plenty insulated for AZ heat. After I get the bins patented, I will definitely post it on here.

    • Desmond
    • August 16, 2013

    This summer I cut down some unwanted trees from my yard and mulched them. I started adding the mulch to my worm bins and the result is a richer mix in my opinion. I was surprised to see it only took a week for the mulch to break down along with the rest of my kitchen scraps. Also, the worms still look happy and healthy.

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