I'm building a house in Ubud, and every day the polite contractor has more questions for me. Where do I want this window? Do I want town water or a well? Tile roof or ylang ylang? And what about sewage treatment? I could build a nice septic tank, but I'd still have to treat the residue; a biological treatment system requires chemicals and regular maintenance. So that decision was easy - I'd wanted a Wastewater Garden ever since I'd learned about them last year. But the cost was high and I didn't have the technical skills to make one myself. Then I learned that Yayasan IDEP (Indonesian Development of Education for Permaculture) now provide consulting for the installation of these systems locally at a reasonable cost.
IDEP technicians have been trained by two experts. Dr Mark Nelson was in charge of research and management of the constructed wetland which treated all human, laboratory and domestic animal waste in mini-world Biosphere 2. Emerald Starr was the first builder in Bali to install wastewater gardens at his ecological hotel/retreat centre, Sacred Mountain Sanctuary. He has since worked with Dr Nelson to install systems for houses, hotels and schools in Bali. Dr Nelson is Vice President of the Planetary Coral Reef Foundation, which helped develop wastewater gardens and has authorized Yayasan IDEP as the only licensed holder of this technology in Indonesia. Nelson and Starr will work with IDEP to ensure that every system IDEP installs is designed scientifically and built to the highest quality standards.
In most of the world, sewage has traditionally been seen as a problem to be kept out of sight. The wastewater garden concept sees sewage as an opportunity to use natural nutrients to create a clean, beautiful environment.
Typically, a toilet is attached to a septic tank -- two chambers in which 'grey water' from basins and showers and 'black water' (human waste) is mixed and partially digested. But when the tank is full there is nowhere for the 'sludge' to go except to leach out into the surrounding ground, which is why the grass is always so much greener there. Heavy rain and overflowing or badly designed septic tanks allow untreated sewage to leach into the groundwater and enter public waterways.
Wastewater Gardens, or 'constructed wetlands for sewage treatment' take this sludge and magically transform it into clean, clear water, with 99% of harmful bacteria removed. This is not an experimental technology. It has been exhaustively researched since its development in Germany and the United States 30 years ago, where there are now many large projects.
The system is deceptively simple deceptive because it must be properly installed in order to work perfectly. Waste from the toilet empties into a specially designed septic tank with a filter where the solids are gradually consumed by bacteria (a well-designed tank can reduce solid waste by 65-95%). The nutrient-rich water then passes into a nearby Wastewater Garden which is lined with cement or a non-permeable membrane to prevent untreated sewage from leaching into the groundwater. The bottom layer of the garden is the contaminated water. A 5-10 cm layer of fine gravel covers this, excluding the air. Then a garden of carefully selected and combined vegetation is planted on top. There's a long list of plants that flourish in these conditions, including flowers, vines, palms and fruit trees.
How does it work? The contaminated water is filtered through the gravel and drawn up by the plants' roots. Microbes that colonize the gravel also help break down the bacteria. The contaminants are absorbed as nutrients and the water is quickly purified. Treatment levels for Biological Oxygen Demand, fecal coliform, nitrogen and phosphorus reduction and total suspended solids are better than US and European Secondary Standards for urban sewage treatment and far exceed conventional septic tank or leach field treatment. For example, fecal coliform bacteria counts are reduced by over 99% without chemicals. The system works just as well with heavy metals and non-organic pollutants, even those as toxic as mercury, so there may be important applications in cleaning up batik and industrial wastewater as well.
The system is self-perpetuating and virtually maintenance-free. Because the water isn't exposed to the air at any point, there are no mosquitoes or smells. No electricity is required. All that's needed to keep the system operating smoothly is wastewater, plants, warm temperatures and sunshine. Fruit produced above the waterline is contaminant-free and safe to eat. The small amount of clean water that flows out the other end can be used to water the flower garden.
Wastewater Gardens are almost infinitely expandable. I am installing the smallest garden, but should the system ever need to serve a larger group of people, another compartment can easily be added. The technology is ideal for hotels and factories. Existing septic tanks, if well designed and of sufficient capacity, can be adapted to run into a Wastewater Garden.
Constructed Wetland Ecosystem Treatment Systems have been approved by the Departments of Environment and regulatory agencies of 16 countries including Germany, the UK, the USA, Canada and Australia. Wastewater Gardens are being installed in Mexico, Belize, the Bahamas, the United States, Egypt, Poland, France, Indonesia and Australia. Over 80 projects have been implemented since 1996, treating populations from house-size to hotels and theme parks of 1500 people daily. The Wastewater Garden concept was recently endorsed by BAPEDALDA, the Indonesian environmental authority. Major projects receive BAPEDALDA certification, and are eligible for bank loans repayable over 15 years.
I've seen several wastewater gardens in operation here in Bali and they thrive in tropical conditions. The lush gardens of papaya, banana, ginger, lilies and papyrus are beautiful and odour-free.
Cost, of course, depends on project size. IDEP, a non-profit organization, provides consultation on required size of septic tanks, separation of grey water and black water, sizing and siting of the treatment systems, construction drawings, site visits during construction to ensure high quality control, garden design and plant selection. Fees begin at Rp 1,500,000-2,000,000 for small house projects. A percentage of the fee is returned to the Planetary Coral Reef Foundation (U.S.), which helped develop the system, for education and research and to IDEP for its work in environmental education and sustainable agricultural systems in Bali and Indonesia.
For more information on wastewater gardens or for a consultation and quotation, contact Dian at 0361 977088 or email idepwwg@dps.centrin.net.id or diantjendono@yahoo.com
