Applying Synergy Farm Concepts to Arcosanti
Paul Wright
Arcosanti is a community founded upon Dr. Paolo Soleri's concept of arcology, in an arid location between Phoenix and Flagstaff, Arizona. The following basic Synergy Farm concepts appear to be consistent with Dr. Soleri's ideas of "Containment of Habitat" and "Self Reliance":
1. Aquaponics
1. Aquaponics is the symbiotic connection of an aquaculture system (growing seafood), with a hydroponic system (growing plants without soil). The waste products from the aquaculture system are used as organic fertilizer in the hydroponic process; plants get nutrients as they require, at the same time filtering the water for the aquaculture system.
2. Synergy Farm contemplates an iterative aquaponic process in which small crops are harvested daily, as opposed to larger crops being harvested less often. This allows optimum yield for the available resources of space and water.
1. Suppose, for example, a daily requirement of ten pounds of fresh spinach:
1. Each day, enough new spinach plants would be started (either germinated from seed, or rooted using vegetative propagation techniques) to yield at least ten pounds at maturity. When changing growing conditions throughout the year result in differing periods of growth to maturity, the daily volume of new plants would be adjusted accordingly in order to maintain a steady, predictable yield.
2. Each day, a batch of fully rooted plants would be transplanted into floating blocks that support the leaves while allowing the roots to hang down into the nutrient solution. From that point, the plants would move through the hydroponic growing troughs like an assembly line -- with the older plants toward the harvest end and the newer plants toward the propagation facility.
3. Each day, the oldest batch of mature plants (presumably enough to yield the required amount of useful spinach) would be harvested.
4. This system is easily scalable upward. The yield is limited primarily by physical space in which to house the hydroponic troughs, and the amount of nutrients available from the aquaculture system. The hypothetical amount of ten pounds per day (for the example given) is a very, very modest level of production.
2. Also suppose, for example, a daily requirement of 50 pounds of fresh fish fillets:
1. Breeding pairs of the selected fish (Tilapia, also known as Nile Perch, is the recommended species because of several favorable characteristics) are maintained in breeding tanks with optimized light, temperature, feed conditions. A breeding pair of Tilapia will generally produce about 1,500 new hatchlings at 10-day intervals.
2. After a few days, each new batch of hatchlings would be transferred from the breeding tank, into a separate maturation tank. For the next 4 months, they grow to the fingerling stage in this tank. If a breeding pair produces as expected, there would be more fingerlings than are necessary -- the excess would be raised in an extra tank to meet unusual demand, or other purposes.
3. For Tilapia, the grow-out phase to harvest size (about 2.2 lbs, yielding about 1 pound of fillet) lasts as much as 6 months, so there should be 6 grow-out tanks, increasing in size according to the Fibunacci sequence observed as approximating the growth rate in marine species: 1, 2, 3, 5, 8, 13, 21 (each number after 2, is the sum of the two previous numbers). So, the first tank is 100 gallons, and the last is 2100 gallons. This series maintains a ratio of less than one pound of fish per gallon, as appropriate for intense aquaculture, while minimizing use of scarce resources like space and water.
4. The oldest batch of fish would be in the largest tank, from which they would be harvested daily over the month. With expected loses, each batch would yield more than enough mature fish to harvest 50 pounds per day. Any excess could be transferred to the extra tank to meet unusual demand, or other purposes.
5. When the month ends, the largest tank would be empty of fish, at which point the water and fish from the each smaller tank up the line would be allowed to flow by gravity to the next larger tank.
6. This system is easily scalable upward. The primary limits are physical space, water supply, and feed supply. To increase to 200 pounds per day, the monthly periodicity could be changed to weekly by adding three identical sets of tanks (including breeding pairs). In order to increase to 1,000 pounds per day, the weekly periodicity could be changed to daily by adding 16 more identical sets of tanks/breeding pairs. This would easily supply 4,500 people -- unless all 4,500 wanted fish, every day!
2. Waste treatment
1. Active vermi-composting of non-recyclable garbage and other Municipal Solid Waste (MSW), using the "Worm Gin" process patented by Harry Windle of Gainesville, Florida.
1. The end products of this process are a high-grade compost, and a steady supply of live worms and egg cases.
1. The compost could be used as a mulch, and to improve the soil in planters, gardens, orchards, and fields.
2. The compost also could be used for a form of local terra forming, in connection with judicious selection of cultivars (bamboo, perhaps), to grow a forest from which lumber and other forest products might be developed locally over the long term.
3. The worms and egg cases could be sold, used elsewhere for soil improvement, or to supplement fish feed for the aquaponic system.
2. A Worm Gin could be a revenue source in the following ways:
1. by selling vermi-compost in packages (e.g., to garden centers) and in bulk (e.g., to landscapers)
2. by greatly reducing or even eliminating MSW disposal costs;
3. by providing an alternative for neighboring communities that presently dispose of their MSW in traditional landfills. Not only would a Worm Gin likely cost less than using a landfill in the short run and in the long run, in any event the Worm Gin is vastly more environmentally sound.
2. Anaerobic decomposition of agricultural wastes, sewage, MSW, and bio-mass (the latter two, as may be necessary to maintain sufficient production levels of fuels), using proven public domain ideas and readily-available products.
1. The end products of this anaerobic decomposition process are "bio-gas" (mostly CH4 but also including some CO2), effluent water, and sludge consisting of incompletely decomposed material. The latter two must be treated further.
1. the CH4 can be collected and used as a clean fuel in a fuel cell that produce electricity, and has only water and thermal energy ("heat") as byproducts.
2. the CO2 can be collected and used to enhance greenhouse production.
3. Both the effluent water and the sludge must be treated further for sanitary purposes.
1. The effluent water should be treated in a constructed wetland.
2. The sludge should be composted in the Worm Gin, along with MSW.
3. Judicious use of water resources:
1. Rainwater harvesting, storage, and treatment to potable standards, using proven public domain ideas and readily-available products. This water would be very suitable for supplementing other sources of potable water, or in an intensive aquaponic system that has the equipment to ensure very clean water.
2. "Gray water" harvesting, storage, and treatment to near-potable standards, using proven public domain ideas and readily-available products. This water would be very suitable for toilet flushing (to conserve potable water supplies), natural evaporative cooling (NEC), non-agricultural irrigation--or even agricultural irrigation after O3 and/or UV light purification. (Actually, gray water generally is suitable for agricultural irrigation, even without purification, but the idea is so aesthetically unpleasant to some people that it is outlawed in many places.)
3. Recyclable constructed wetlands as bio-filters for treatment of anaerobic digester effluent water. The water leaving the bio-filter would be suitable for NEC, non-agricultural irrigation, or agricultural irrigation after O3 and/or UV light purification.
1. The bio-filter would consist of an earthen berm with a greenhouse-type cover to collect maintain consistent growing conditions and to minimize evaporation losses. Internal flow channels would be created with soil blocks, to promote settling of solids and to ensure that all entering water takes the full "transit time" of 30 days before leaving the bio-filter.
2. The constructed wetland should be planted with Water Hyacinth, a floating plant. Water Hyacinth has been shown to be a good plant for removing impurities in a constructed wetland. Excess Water Hyacinth can harvested as a feedstock for the anaerobic digester, to increase bio-gas production -- or for the Worm Gin, to increase compost production.
3. Each bio-filter would be recycled by moving the cover and inlet piping to a new constructed wetland, then bulldozing and planting the old site with an appropriate non-agricultural cultivar (like bamboo). The earthen berm and soil bocks used to build the constructed wetland would simply become part of the soil. In about five years, the resulting bamboo "forest" would produce the same amount of flooring and engineered lumber products, as 30 years' growth in trees in the same area.