house construction 4 60 - 80% nutrient recovery Organic waste can be processed three ways. Kitchen scraps can be fed directly to animals or be composted in an aerobic worm compost for personal garden use. They can also be fed into the D-SARR reactor and turned into biogas. COST & LABOR ESTIMATES Costs for vermiculture (worm compost) are minimal, amounting to less than 30 € for a small system in each household. The costs of the D-SARR system are described in the previous section on wastewater treatment. 5 10 - 20% vegetable & fruit production used for intensive food production, since there will also be recreational spaces in these areas. A very realistic target for phase one is 10 - 20% of vegetable and fruit production on site. COST & LABOR ESTIMATES DEMAND-SIDE MANAGEMENT Nutrients collected from the wastewater and organic waste treatment system can be used on site for food production. This creates a closed cycle between nutrient collection and food production. Remaining nutrients can be sold for a profit by the community. The urine separating toilets will produce an estimated 250 kg of struvite per year, which is a significant amount of phosphorous. Only about 10% will be used on site for food production. The various rooſtop gardens and greenhouses can all be used by the community to produce food on the Schoonschip site. At the end of phase one, there should be approximately 1200 square meters of greenhouse and green roof space for this purpose. At an average production output of 25 kg per square meter, which is easily achievable with well managed gardens, the site could produce approximately 30.000 kg of fruit and vegetables per year. This would be sufficient for all of the community’s fruit and vegetable demand (if they were to eat only locally produced crop types). We are assuming that not all of this space will be If green roofs and greenhouses are already installed as part of the initial building structure, the added cost of cultivating these areas is not extremely high. Plants propagated from seed are less expensive that plants purchased for transplanting. Nutrients will be supplied from the on-site wastewater treatment system, and water will be collected from the rainwater system. The primary expense is in the form of labor, which can be quite high and require a great deal of regular attention. We estimate at least four hours of labor on average throughout the year for each sizable plot under cultivation. 76 / 146 Pagina 75
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