Vermicomposting Commercial Kombucha Brewery Waste

Updated: Jun 23, 2021

What is Vermicomposting?

Vermicomposting is composting with worms. In our case, red wigglers. These worms will eat almost anything that at one point grew out of the grown, including our tea leaves, fruit, SCOBY, cardboard, paper and turn it into worm castings – known as black gold amongst gardeners. The worm castings can be used as organic fertilizer teeming with beneficial microbes that also defend against fungal disease. Or it can be mixed with water to create worm casting tea, to water your plants with.

There is so much to discuss about worms, worms’ castings, composting, and how to do it effectively, but what this article will focus on is the efficacy of using red wigglers to dispose of our kombucha breweries waste.

Logistical Considerations

Is it possible?

Firstly, let us determine if it is even possible to use red wigglers to compost our kombucha brewery waste. Red wigglers require a balanced diet of nitrogen rich foods, and carbon rich foods. Nitrogen rich food includes fruits and greens. Carbon rich foods are materials like paper and cardboard. Our organic waste includes:

  • Tea leaves

  • Various fruits

  • Herbs

  • Ginger roots (?)

  • SCOBY (?)

We can be sure that the red wiggler will devour the tea, fruits, and herbs, but we are not so sure about the ginger roots or SCOBY. Red wigglers do not like irritable foods like ginger roots, garlic, or onions. As for the SCOBY, it is mostly made of cellulose which the worms should eat, but the acidity could be dangerously low. Red wigglers prefer a neutral pH of 6-7, while our SCOBY could be as low as 2.8 pH. In fact, our spent fruits will likely have a 3-3.5 pH since they are all soaked in our kombucha.

We can address these potential problems by disposing of the ginger roots separately and adding a pH balancer like crushed eggshells or limestone to neutralize the SCOBY and fruits.

In addition to the organic fibres, we will have to add lots of carbon rich bedding material, such as cardboard and paper. Because most of our compost additions will be water saturated, we will need amble dry bedding material to avoid overwatering our worms. It is safe to assume that we will have enough dry bedding material to supplement our nitrogen rich foods, from all the different shipments and paper we receive and use.

My conclusion is that with generous dry bedding addition, the use of a pH balancer like limestone and the exclusion of ginger roots, our brewery should be able to produce waste materials that would be ideal for vermicomposting.

Setup Size Requirements and Implementation

At peak production, we can expect to produce around 50 lbs of organic waste excluding ginger roots, every week. Add another 10 lbs for cardboard and paper waste. That means we need a vermi-compost system capable of handling up to 60 lbs of waste materials every week during peak season.

Red wigglers are known to eat up to half their own body weight per day, though after further research I am convinced that number is highly exaggerated, and it is close to a quarter of their own body weight. For our system, let us be conservative and assume they consume 25% of their body weight. At 60 lbs per week, that means we would need to compost about 8.6 lbs per day, which translates to a requirement of about 35 lbs of worms.

A rotating three bin system is preferred, so that each bin may be given breaks between feedings to assess the amount of feed the worms can accept. Therefore, we would separate the 35lb’s of worms into three large containers and feed on a rotating basis. Luckily, we have gated yard space for these containers. There are lots of things to consider when choosing your container setup, but after some research and consideration, we believe the 275 Gallon ICB plastic totes is great for us because of their convenience, mobility, low cost, and drainage port at the bottom. If we were worm farmers, it would probably be better to build a custom setup, but we are primarily just using it as a waste system.

Threats to Our Worm Habitats

Since our summers almost never go above 30 degrees Celsius, we will not be concerned about over heating if the bins have shade. However, our winters may be cold enough to kill worms if bin temperatures drop below 0 degrees Celsius. Therefore, we will have to keep whatever container we choose in either shipping containers or an insulated area. Perhaps the cheapest option will be to wrap the containers in fleece or wool material and create an enclosure with an automatic on/off space heater. The low temperatures throughout the winter will negatively affect our worm’s consumption rate and reproduction rate. It may be worth infrastructure investment and a higher heating bill to ensure the system can handle our waste throughout winter.

Logistical Conclusion

The project will be possible, and we have the space required to do it. The main logistical issues we will have to address are:

  1. Controlling the pH so it stays within 6-7 pH using limestone or crushed eggshells.

  2. Ensuring the bins are warm enough over the winter to remain productive.

Financial Considerations

Potential Savings

First, let us consider our current composting and recycling costs. We will discuss the thought processes below then show them on an excel sheet.

We pay $60 / month to dispose our compost, and another $60 / month to dispose our recycling. That is a cost of $1440 per year. Ideally, we would be able to eliminate these costs in lieu of the vermicomposting system.

Initial Investment Cost

Retail value for approximately 1 lb of red wigglers is $45. Fortunately, we have been offered a good deal on 20 handfuls of worms from Burnaby Red Wigglers, which we will assume is about 15 lbs of worms (each handful is a little less than a lb), at a cost of $450. We could spend $900 for approximately 30 lbs of worms and almost immediately be capable of handling all our compostable waste.

Alternatively, we could purchase the 15 lbs of worms and attempt to breed them. Worms can double their population every 60-90 days in ideal conditions. Because we would likely have less than ideal conditions, due to the nature of its usage as a waste system and not a farm, I do not think we would achieve this population growth. I believe it may be possible for us to double our population in 6 months to a year, due to the cold winter where little reproduction is likely to occur. It can be expected we would pay for another year of compost and recycling fees while our worms reproduce.

This is not necessarily bad. Considering we will likely learn a lot while we take on this project, perhaps it is smart to hedge our bets and start smaller. After all, loosing $450 worth of worms is better than loosing $900 worth of worms.

So, let us consider the worm setup cost to be $450, so we can learn as our worms grow. Then let us assume we can get 3 used ICB totes for $100 each. Add $100 each for materials to pest proof and provide shelter from sun and rain. That is a total setup investment of approximately $1050.

Operating Costs

We will not consider the space as lost potential revenues, as the 3 tanks will not take considerably more space than our recycling and compost bin anyways. We would not be facing an opportunity cost as we would not be renting out the space otherwise.

However, we should account for maintenance cost for the worms. The act of feeding the bins and taking our the recycling is similar labour, so we will only consider additional labour to feeding. We are not experienced worm farmers. I can imagine that we will spend an average of 2 hours of labour per month dealing with potential issues that arise or dealing with miscellaneous materials not accepted by our worms such as ginger roots. Averaging labour at a cost of $20/hr, this adds an expected labour maintenance cost of $480 per year. Add $120 per year for potential limestone costs to balance pH. This makes our anticipated recurring expenses per year $600. Since our cost of traditional compost and recycling is $1440 per year, our expected yearly savings is around $840. However, this $840 can easily be washed away by unexpected costs such as materials, tools, and winterizing costs.

We cannot be entirely sure what our unexpected costs will amount too, but we can be sure there will be some. For example, the cost of disposing of any additional scrap recycling or ginger roots not used in the system, or decreased capacity throughout the winter making our system incapable of handling all our waste, resulting in added conventional composting costs. Or perhaps most certain of all, our winterizing costs to keep our worms warm enough through the cold season. These costs will not be directly accounted for and will be lumped into potential unexpected costs for convenience.

What is important in these calculations is the belief that you will not loose substantial money operating the vermicomposting system compared to traditional haul out compost and recycling.

We are not overly concerned about saving money, or even spending a little bit of money on the system, because the system itself has many additional benefits for the business.

See our calculations below:

Benefits for the Business

Appreciating Value

Warren Buffet believes that the 8th wonder of the world is compounding interest. If Mr. Buffet gets excited about a 7% annual return on the S&P 500, he should run the numbers on a worm farm. When given the right conditions, red wigglers can double their population every 3 months. That would be a 400% annual return, compounding. Of course, there are maintenance costs associated as your worm farm grows, but we can at least feed and manage our worm farm at little if any additional expense for the first few years. Even considering how our worm farm may only double every year, due to harsh winter conditions and overall neglect it may receive as a waste system compared to a breeding farm, that is still an amazing exponential return. Assuming the market value for worms does not drop substantially, we will be holding an asset that doubles in value every year. That is crazy. Not many physical assets that require relatively low maintenance and space requirements can do that. If we continue to grow and manage our worm habitats, we could end up with $7200 worth of worms by year 5, using our conservative growth estimate. If we focused a bit more on worm farming, and achieved a 6-month doubling rate, we would have bred $230,400 worth of worms by year 5. If we were worm farming experts that gave them ideal conditions to thrive, we could produce $2.9 million dollars worth of worms by year 5. That is the absurd power of exponential growth. Of course, there would be substantial habitat and management costs as mentioned. There may even be additional feed costs if we cannot produce enough waste to feed the worms or find a free source. I did briefly consider the merits of a worm farming business and determined that we should focus on what we know – brewing kombucha.

Marketing Value

I am confident that our consumer base and target market will appreciate the fact that we compost our waste in house. Vancouver’s composting facilities involve a lot of energy to heat the organic waste, and a greater carbon footprint due to the costs of transporting our wastes to the third-party facilities. While my intuition says vermicomposting is superior to conventional composting when done in-house, further research is required to be sure what the quantifiable environmental benefits of vermicomposting are when compared to conventional composting.

Environmental comparison aside, the vermicomposting system will provide valuable worm castings. Worm castings is highly valuable organic fertilizer. We could use these worm castings to leverage a partnership with a local community farm for publicity, or simply give it away to our kombucha customers as a bonus. We could also sell the worm castings. The market value for a 5-gallon pail of worm castings is about $30. We can also sell any excess worms.

We could also use the worm castings to grow our own herbs in the yard to use in a limited release kombucha!

Business Opportunities

Vermicomposting for other businesses with similar waste, or consulting for other businesses wishing to adopt a vermicomposting system for their operations could both be good additional revenue or marketing channels.

Kombucha breweries are an ideal business for adopting a vermicomposting system because of how we produce so much worm acceptable materials like tea leaves, herbs, SCOBY, fruits, cardboard, and paper. We could collaborate with other kombucha breweries to haul their compost at a small fee or be paid to consult them on their very own system.

I also believe that recreational sites could greatly benefit from a vermicomposting system for human waste. Imagine, instead of smelly outhouses that need to be pumped out, you used worms to purify human waste then distribute the worm castings back into the parks eco system. Perhaps the government or new buildings will hire worm experts, such as our future selves, to setup large scale vermicomposting facilities for green initiatives in the future! In fact, Sombrio already has its very own recreational site with this system in place. See Burnaby Red Wiggler’s blog post about Sombrio’s system here:


Vermicomposting our kombucha brewery waste sounds like a fun project that is relatively inexpensive to start, and low maintenance cost. We could potentially see some small savings when compared to conventional composting but may also suffer small losses on the investment after unexpected costs, it is hard to say. However, there is large upside in appreciating asset value, marketability, and business opportunity. Therefore, Tality Kombucha plans on being the first kombucha brewery in the world to adopt a vermicomposting system for waste management!

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