Worm composting and vermitechnologies applicable to sanitation - S. Zorba Frankel1

¹ Managing Editor, Worm digest, Eugene, Oregon, USA.

The past two decades have seen renewed interest in finding ways to harness earthworms to convert our increasing amounts of organic waste into humus. Various types of earthworm are being used to turn “waste” into a useful resource and enabling some existing waste treatment systems to be operated more efficiently. Waste treatment systems that incorporate worm technologies can accept a wide range of organic matter inputs, including human excreta, can destroy pathogens overtime, and create a nutrient-rich soil amendment as a product.

Some of these systems can be built with simple materials, and on small budgets. They can be built to varying sizes to serve different-sized families and communities. Many require little or no water beyond the amount provided by the organics.

This article provides basic definitions and explanations of vermicomposting and “vermiculture ecotechnology”, and describes their successful use in many different settings. More information on these projects may be obtained from the publications listed at the end of the article.

What is vermicomposting?

Vermicomposting (worm composting) is the conversion of organic wastes by surface-dwelling earthworms into worm castings (excreta). The redworm species Eisenia foetida and Lumbricus rubellus are most commonly used in vermicomposting. In nature they are often found where leaf or other organic litter falls onto the surface of the soil and remains damp. In that setting they play the role of “emergency clean-up crew.” When harnessed, their natural abilities in reproducing quickly and eating up to their weight in organic materials each day are taken advantage of.

In many vermicomposting systems, and particularly those in homes, schools and industries in industrialized countries, redworms are housed in bins. Bins are most often made of wood, but plastic, metal or any material which is not dangerous to the worms' survival can also be used. Some manufacturers offer popular plastic bins for home use, designed with holes for aeration. Models also exist that sport such features as a lower chamber and spigot to collect and drain “worm tea” for watering plants, as well as multiple-worm composting layers, and even a mechanical device for harvesting castings.

As with traditional composting, a balance is sought between carbon-rich materials like leaves and straw, and nitrogen-rich material like food waste and manures. Usually, these two types of material are mixed or layered in the worm beds to ensure more complete decomposition and a good finished product. Worm bins in home settings are first filled with moistened carbon-rich bedding like straw, leaves, or shredded newspaper. Then a small amount of garden dirt is added (the tiny rock particles aid the redworms' digestion), and finally the redworms are introduced into their new homes. Feeding can be daily or less often, depending on the user's schedule. Redworms will eat about half their own weight in food wastes per day (in most bins, under average conditions). As the bedding decays via the activity of bacteria, the worms will simply begin eating it, too! Castings can be harvested within three to five months, depending on how finished a product is desired. After harvesting (there are several methods), the worms are put back into their bin with fresh bedding, to begin the process over again. These are the most basic instructions for small! worm bins. For more detailed information, consult the publications listed at the end of this article.

The following are project examples using redworms which have been reported by Worm digest, a US magazine.²

² Worm digest began publishing in 1993 with the aim of promoting the raising of redworms to convert organic wastes into humus in households and schools. The range of vermitechnologies known and promoted has widened since then, but vermicomposting with redworms in bins remains the most well-known method. Interest in worm composting in the US seems to be growing, judging from the increased media coverage of worms, worm curricula in schools, and the growing number of requests for Worm digest subscriptions, publications and assistance.

School lunch “wastes” not wasted

At Mill City Middle School in Mill City, Oregon, USA, sixty 5th-grade students use redworms, in a well-designed bin, to vermicompost their food waste. They built five OSCRs (Oregon Soil Corporation Reactor, named after the company that designed it) from plans they purchased. The OSCR is a tall, rectangular plywood bin with large upper and lower chambers separated by nylon rope weaving back and forth every few inches. The upper chamber houses the redworms, and there is a plywood lid to keep pests and light out. Students add food and paper waste to the upper chamber each schoolday. As the composting mass grows higher and the redworms move upward, they leave their castings below, suspended above the nylon rope. The lower chamber, accessed through a hinged door, is a collection area for finished castings. A small rake is used to dislodge the castings into the lower chamber, from which they are easily removed. Although only a year old, this project has converted the food wastes of these sixty students into worm castings, and both students and teacher are enjoying working with worms.

Turning hog manure into a resource

Vermicycle Organics, Inc., in Charlotte, North Carolina, USA has tested the use of redworms to process hog manure into organic fertilizer on a farm in their region. Partners Tom and Chris Christenberry (who, as farmers, had previous experience with worm composting) and Michael Edwards began their tests with open-field worm composting, but found that weather created problems, including a poor end-product. Now they separate the liquids from the solids in the manure and each week spread over five tons of manure solids in thin layers on top of several long, raised wooden worm beds in a greenhouse. A shade cloth, automatic misters, fans and greenhouse curtains help to keep conditions optimal for the redworms. Their product, Vermicycle^TM Worm Castings, has been received well by retail outlets and the three partners plan to expand their work to more farms soon.(1)

Vermicomposting toilets

Clivus Multrum

Aerobic composting toilets are already used in many parts of the world to turn human waste into soil (2). Redworms can enhance their operation, requiring only the addition of a simple moistening system. Such has been the experience with the Clivus Multrum system which has made regular use of redworms for the past five years. The Clivus system was first created in 1939 in Sweden, and sold in the US and elsewhere by Clivus Multrum, Inc. beginning in 1973. A typical home might include an ultra-low-flush toilet, a kitchen waste-disposal chute and a large composting chamber below the floor or in a basement. “Clivus” means slope, named for the sloping plane within the composting chamber that directs liquids to a separate area below the composting mass, from which it is then removed by pump. A fan-driven ventilation system vents odours from the toilet room. A family of four can expect to remove small quantities of (solid) compost via a door at the front of the composting chamber after a period of one to several years. An estimated 10 000 Clivus Multrum toilets are in use worldwide.

Figure

AlasCan

Clint Elston of Minnesota has developed a worm composting system for colder climates. He had experience selling Clivus Multrums while living in Colorado. But when he installed them in Alaska (where most rural villages do not have adequate sanitation systems), he found that the Clivus systems did not operate well due to the extreme cold. So, over twenty years ago, he began work on the AlasCan system, a complete organic conversion system for households. At the heart of the system is the vermicomposting tank, which accepts toilet wastes from an ultra-low-flush toilet (a marine toilet) and from a dedicated kitchen sink with a waste-disposal unit. The tank is super-insulated (R-20+) and pre-warmed by house air in a heat exchanger. The other main component of an AlasCan system is the wastewater treatment system, which accepts all household greywater (including from showers, bathtubs, sinks and washing-machines). The AlasCan system is designed for minimal user involvement and uses motor-driven agitators, a pump, sprayer and exhaust fan to ensure continuous good functioning. According to AlasCan, the system produces about 10 cubic feet of vermicastings per year for a household of two adults and two children. The system's cold-weather capabilities have won it some acclaim. At this time, Buckland, Alaska, a village of 82 homes, has passed resolutions to install the AlasCans exclusively, and has contacted another village in order to help them do a pilot project.

Vermiculture ecotechnology

Dr Uday Bhawalkar is director of the Bhawalkar Earthworm Research Institute in Pune, India. He researches and designs systems that use aerobic bacteria and burrowing earthworms to convert organic wastes (including human excreta) into humus. He calls the basic method he developed “vermiculture ecotechnology” in which “diverse organics, via an already-operating ecosystem (bacteria, managed by burrowing earthworms), are turned into plant nutrients.” The key players are aerobic bacteria living in the earthworm's burrow, gut and surrounding soil, plus the earthworms themselves, which preferentially encourage good bacteria while discouraging unwanted (anaerobic and pathogenic) bacteria.

When choosing a site for vermiculture ecotechnology, a root zone must be available. If the site does not already have plants growing on it, then some trees or taller bushes must be planted there. Next, a thin layer of organic wastes is applied directly on the soil, along with some rock dust (powder) to provide necessary plant minerals and to balance the pH. A moisture-retaining layer of leaves or straw, etc., may be added. When available, some of the vermicastings from another site will get things started more quickly, especially if the soil is not already very biologically active. Food waste can be added at an increasing rate, as bacteria and worm populations grow. Again, for more detailed instructions, consult the books in the resources section.

In India, Dr Bhawalkar has put vermiculture ecotechnology to work at many sites with varying organic waste sources. Most notable has been the project at Venkateshwara Hatcheries, Ltd., in Pune. This poultry processing plant produces four tons of poultry offal daily, which goes to twenty 120 m² concrete bins inoculated with a culture of the native burrowing species, Polypheretima elongata. Trees have been planted along the mid-line of the bins and, judging by their health, provide assurance that the vermiculture is proceeding well. Bhawalkar calls what is left after the bacteria and worms have worked through the material “biofertilizer”. These microbially-rich vermicastings, full of beneficial bacteria, are sold to farmers under the name of “Biogold”. Venkateshwara Hatcheries, Ltd. plans to use vermiculture ecotechnology at its other 12 operations in India as well.

Although Dr Bhawalkar has shifted his focus to another, newer vermitechnology, several people are still very active in spreading the use of vermiculture ecotechnology. Rahul Babar, a partner in NRG Tech Consultants, offers expertise in vermiculture ecotechnology for setting up complete and ready-to-use solid and liquid waste management projects. Shantu Shenai, director of the Green Cross Society and SOS (Save Our Selves) in Bombay, India, has initiated nearly 20 projects in that area using the Bhawalkar method.

Figure 1: Cross-section of vermifilter

In the vermifilter a group of selected plants provide an active root matrix that creates the desired microclimate for both bacteria and earthworms. This root matrix feeds on the inorganics and other growth factors produced by the bacteria and earthworms, while at the same time sending biofeedback to the bioprocessors, letting them know what the plants need. There is little operation and maintenance required, provided the designed loading rate is not exceeded. (Typical design parameters: Hydraulic loading up to 0.5m/day and organic loading up to 1 kg/m2/day). Stephen White, from Worm digest #8.

Vermifiltration of sewage

The vermifiltration of sewage (3) is an application of vermiculture ecotechnology designed by Uday Bhawalkar. It was adopted at the Sahjeewan School at Panchgani (Maharashtra) after the failure of their septic system due to clayey soil. The project was set up by Bhawalkar, and by 1995, was handling the waste of over half of the school's student population of 750.

The Sujala technique

Dr Bhawalkar is currently involved in promoting his newest technique, “Sujala” (which means “clear water” in Hindi). The technique makes use of the beneficial bacteria fixed on the castings of a specific species of earthworm (again, Pheretima elongata in projects in India). Sujala is in use at the Taj Group of Hotels in India. These hotels, located in remote sites, sought to use natural methods for wastewater treatment. V. Mahendrakar and B. B. Hallett (4) report in issue #15 of Worm Digest'. “In the existing septic tanks, by adding Sujala, BOD [biochemical oxygen demand] levels were reduced from 200 mg/l to about 30 mg/l and odour was reduced and water clarity increased in 3-4 weeks of operation. Approximately 150 kg of Sujala bacteria were added to a 15 m³ septic tank.” To summarize, after three to four months they saw an increase in pH from 6.5 to about 7.1 and an end to odours, a BOD and COD [chemical oxygen demand] reduction of between 50 and 80 per cent, water output at a quality level for use in the garden and a savings of about US$ 16 per day in electricity.

Conclusion

Presently we have a great need for efficient systems that process our increasing organic wastes. At the same time, in many parts of the world, our soils are growing poorer because we do not return to them as many or more nutrients than we take. Both problems have a common solution: we need only ask the capable earthworm for its help.

References

(1) Riggle D. The business of vermicomposting. Biocycle journal of composting and recycling, September, 1996, 54-56 (Biocycle, 419 State St, Emmaus PA 18049, USA. Tel: +1 610 967 4135.) Single copies US$ 6.

(2) Rapaport R. Aerobic composting toilets for tropical environments. Biocycle journal of composting and recycling, July 1996, 77-82. (Biocycle, 419 State St, Emmaus PA 18049, USA, Tel: +1 610 967 4135.) Single copies US$ 6.

(3) Whites. Vermifiltration of sewage, now being done in India. Worm digest #8, 1995. (Worm digest, PO Box 544, Eugene, OR 97440-0544, USA. Tel: +1 541 485 0456. E-mail: zorba@wormdigest.org)

(4) Mahendrakar V, Hallett BB. Worm digest #15 (see address above).

Background reading

Worms eat my garbage by Mary Appelhof (2nd ed., 176 pgs). The definitive book on small-scale vermicomposting for adults. (Available from Worm digest for US$ 13.)

Worms eat our garbage: classroom activities for a better environment by Mary Appelhof (215 pgs). (Available from Worm digest for US$ 25.)

Squirmy wormy composters by Bobbie Kalman & Janine Schaub (32 pgs). The definitive book for young people on worm composting. (Available from Worm digestion US$ 9.50.)

Turning garbage into gold by Dr Uday Bhawalkar of the Bhawalkar Earthworm Research Institute (40 pgs.). A good theoretical introduction to vermiculture ecotechnology work. Not a how-to book. (Available from Worm digest for US$ 15.00.)

Vermiculture ecotechnology by Dr Uday Bhawalkar of the Bhawalkar Earthworm Research Institute (283 pgs). A treatise on commercial-scale vermiculture. (Available from Worm digest for US$ 150.00. Colour plates version also available for US$ 190.)

Art of small-scale vermicomposting and vermiculture ecotechnology. A 16-page pamphlet teaching the basics of these two worm technologies. (Available from Worm digest for US$ 5.00.)

Turning garbage into gold (47-minute video) by Dr Uday Bhawalkar of Bhawalkar Earthworm Research Institute. See book description above. (Available from Worm digest for US$ 28.00.)

OSCRTM worm bin design plans (Bin: 3' x 4' x 3' high). Vermicomposts up to 12 pounds of food/paper wastes daily, food added from top, castings empty below. (Available from Worm digestion US$ 35.00.)

The toilet papers (1995) by Sim Van der Ryn. Available for US$ 10.95 + US$ 4 shipping from Chelsea Green Publishing Co., 205 Gates-Briggs Building, PO Box 428, White River Junction, VT 05001, USA.

The humanure handbook (1994) by Joseph C. Jenkins. Available for US$ 19 + US$ 4 shipping from Chelsea Green Publishing Co., 205 Gates-Briggs Building, PO Box 428, White River Junction, VT 05001, USA.

Networking

Worm digest, PO Box 544, Eugene, OR 97440-0544, USA. Tel/Fax: +1 541 485 0456. Subscriptions: US$ 12/yr. to US, US$ 16 to Canada/Mexico, US$ 20 to other countries. Back issues: US$ 3.50 to US, US$ 4.25 to Canada/Mexico, US$ 5.50 to other countries. Set of 15 back issues: US$ 36 to US, US$ 40 elsewhere. E-mail: mail@wormdigest.org. Website: http://www.wormdigest.org

Biocycle journal of composting & recycling. Biocycle, 419 State St, Emmaus, PA 18049, USA. Tel: +1 610 967 4135. Single copies US$ 6. A monthly publication. One- and two-year subscriptions: US$ 63/US$ 103 to US, US$ 85/US$ 147 to Canada, US$ 90/US$ 157 to other countries.

Hallett BB. The Taj West End Hotel, Race Course Road, Bangalore - 560 001 India Tel: +91 80 2255055. Fax: +91 80 2200010, E-mail: environ.south@tajgroup.sprintrpg.ems.vsnl.net.in

Jeremy Criss, Bio-Recycler Corp., 5308 Emerald Dr., Sykesville, MD 21784, USA. Tel: +1 410 795 2607. Fax: +1 410 549 1445.

Abby Rockefeller, Clivus Multrum, Inc., 104 Mt. Auburn St., Cambridge, MA 02138, USA. Tel: +1 800 425 4887.

Clint Elston, AlasCan Corporation, PO Box 88, Clear Lake, MN 55319, USA. Tel: +1 320 743 2909.

Dr Uday Bhawalkar, Bhawalkar Earthworm Research Institute, A/3 Kalyani, Pune Satara Rd, Pune 411 037 INDIA. Fax: +91 212 43 21 53. E-mail: beri@giaspn01.vsnl.net.in

Uday Sawant, Manager Operations, OMNI Biosearch Ltd. (a subsidiary of Venkateshwara Hatcheries), Venkateswara House S, #114 A/2 Pune Sinhagad Rd., Pune 411 030, India.

NRG Tech Consultants, B-213, Shantiban Housing Society, S. No. 52 & 79, Paud Road, Kothrud, Pune 411 029, INDIA. Tel/Fax: +91 212 33 59 26.

© S. Zorba Frankel, Managing Editor, Worm digest, Eugene, Oregon, USA, 1997, edited by WHO with permission of S. Zorba Frankel.

Prepared in association with SARAR TransformaciC