Disposal of food waste has long been a nasty problem. Soggy, rapidly decomposing food residuals are messy to handle, cause obnoxious odors, and may attract vectors and other pests. Kitchen sink garbage disposals only add to the problems and costs by requiring up to eight gallons of water to dilute one pound of food waste. Sending food waste down the sink doesn’t solve the problem; it only transfers the problem to wastewater facilities. Home composting and vermicomposting rank highest in the hierarchy of environmentally preferable options for managing food waste. But not all food waste is generated at home. Schools, restaurants, hotels, businesses, and institutions such as hospitals, military bases, prisons, etc., generate tons of food waste that must be collected, hauled and disposed or composted. Is there a cost-effective and environmentally beneficial method of processing food waste on site for these situations? Mid-scale vermicomposting offers a potential solution for some facilities, but where does one go to find a "how-to manual" of instruction for such a project?
Binet Payne’s The Worm Café: Mid-Scale Vermicomposting of Lunchroom Wastes—A Manual for Schools, Small Businesses and Community Groups tackles the problems of implementing a successful waste reduction and vermicomposting program. Savings of $6,000 in collection and disposal costs were achieved in the first year of Payne’s Laytonville, California school project. Curtailing the practice of washing food waste down kitchen sink garbage disposal systems meant that an estimated 103,000 fewer gallons of water a year were used. Additionally, students, teachers and school staff learned that the virtues of reducing, reusing and recycling produce benefits beyond cost savings. They discovered abundant learning opportunities in a project-based curriculum.
Before embarking on a mid-scale vermicomposting project, it is mandatory that a waste audit be conducted. How much food waste is generated per day? per week? per month? A two-week waste audit during which food waste is weighed will help determine the number of bins to construct and how many earthworms are needed to process the waste. Two common rules of thumb are suggested for estimating stocking rates and space requirements: Use one square foot of surface area to bury one pound of food waste each day and use two pounds of earthworms for every pound of food waste added to the worm bin.
Easy directions for building worm bins from lumber are provided. Four-foot-by-eight-foot bins with plywood bottoms and lids may be set on railroad ties and cinder blocks. Materials for each bin cost about $100 and each bin requires approximately two hours to construct. Where warm weather is a concern, worm bins may be placed in shaded areas (under trees), next to buildings, or covered with shade cloth.
The Worm Café offers a number of great suggestions that are imperative for the success of any vermicomposting program. How do you teach children and adults to separate their waste? Use clearly labeled containers (trash cans) for each of the following: veggie wastes (worm food), protein foods (meat, milk and cheese), bottles, cans, bags, and "yucky trash" (i.e., non-recyclables such as plastic food bags, napkins and tissues). While napkins and tissues are considered paper waste and may be included in some managed vermicomposting systems, health and safety requirements suggest omitting these in school programs where students might come into contact with them.
How can you obtain bedding (bulking agents, carbon sources that, with food waste, allow earthworms to more effectively process waste)? Laytonville’s pre-school, kindergarten, and grades one through eight generated paper waste consisting of discarded newsprint paper, book orders and colored construction paper. School district offices, medical clinics and other businesses were glad to get rid of their waste paper, often supplying paper already shredded because of its confidential information. The school eventually built a "Shred Shed" that allowed for storage and shredding of paper to be used in the worm bins.
Binet Payne demonstrates a genuine concern for the totality of her project that includes building healthy soil as well as processing organic waste. Since much of the vermicompost her school’s worm bins produced would eventually end up in the school garden, Payne wanted to know what could be learned about the presence of toxic substances that might be found within inks and colored papers. "Before I began using the vermicompost produced in our bins directly on our school vegetable garden, I wanted to be certain that it was safe, " Payne writes. A soil laboratory confirmed that insignificant levels of toxic substances (and therefore, not harmful) were found in the vermicompost sent for testing.
Payne communicates a refreshing attitude and approach to the subject of "unwanted critters" in the worm bin. Many vermicomposters are easily annoyed by the presence of flies, maggots, and other "pests" they find lurking in their worm bins. Many folks typically ask, "What should I do about these pests?" Payne instead looks at the worm bin as an ecosystem, occasionally out of balance but able to re-establish balance over time. This is truer for larger systems (mid-scale and up) than for smaller home vermicomposting units. "Throughout all of our trials and errors," Payne writes, "we found that, unlike smaller vermicomposting systems, mid-scale systems are more tolerant of a wider variety of conditions that in smaller systems can cause major problems."
Excellent tips are provided in the chapter "Working Your Bins," where the processes of adding food waste, turning the contents of the bin, and encouraging earthworms to migrate laterally are described. Using her school’s four-bin set up, Payne provides diagrams that show how food waste can be rotated over a 16-week period. Payne suggests using a finishing box for holding harvested vermicompost while it continues to be broken down (finished) by the microorganisms in the bin.
In any waste management system, it is important to plan for contingencies. What happens if there is more food waste than your vermicomposting system will handle? This may happen at the beginning of a new project, particularly if the amount of earthworms to be used has been underestimated. If on-site thermophilic composting is available, an enclosed bin for handling extra food waste should be constructed or purchased. Where does the protein food waste go? Overall, this represented a higher proportion of the total cafeteria food waste (9,360 lbs.) than the vegetative food waste fed to earthworms (3,600 lbs.). Laytonville supplied this protein food waste to chickens and pigs, but Payne did not mention the particulars involved in transferring this waste.
The appendices, bibliography and index supply helpful information amounting to just under half the total number of pages. Classroom teachers will benefit tremendously from the checklist, posters, forms, lesson plans, work sheets, and annotated list of classroom materials. This is clearly a book about teaching vermicomposting written for teachers by an experienced teacher! If you are an educator, you’ll give this book an A+.
The Worm Café is right on target for setting up a school vermicomposting program. Although Payne alluded to the possibility of selling earthworms and vermicompost for school fund-raising, no details were provided. It would have made the book even more valuable if a few ideas about the commercial side of vermicomposting could have been shared. While this book would be helpful for setting up other vermicomposting projects at small businesses and institutions, its appendices make it clear that Payne has written The Worm Café primarily for schools. A chief criterion an institution (hospital, military base, etc.) or small business would have in considering a plan to vermicompost its food residuals is, how much will the new system cost to set up and run, and what will be the savings? Businesses are typically profit-driven and cost-conscious. Some are environmentally sensitive, or at least would like to be thought of in that way. There is still the need for a similar manual that would focus on the cost benefits of on-site vermicomposting, including figures for initial investment, savings on the costs of diverting the organic waste, savings on water usage, savings on use of fertilizers and soil amendments when vermicompost is used for on-site landscaping needs, etc. A convincing case for considering on-site vermicomposting can be made when the written material meets the needs and answers the objections of the intended reader. The Worm Café leaves no doubt that on-site vermicomposting can and should be done at every school facility. It also opens the door for institutions and small businesses to consider doing the same.
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