11Separation
Dispersion of wastes is ignorant of their value.
11.1 Principle 8
Separation may serve different purposes for reuse, recycle, and treatment. For solid waste, food waste (FW) should be separated from other waste because energy could be recovered from the FW. Papers and plastic separated from the solid waste stream could be reused or recycled. For zero water design, it is critical to separate blue (surface and groundwater), green (rainwater), gray (bath and laundry), and black (toilet water). Black water can be further separated into brown (urine) and black (feces). In developing countries, separated urine and feces toilets are promoted by many United Nations programs. N and P could be recovered from the concentrated urine, while anaerobic digestion of feces could generate methane and good organic fertilizer. In developed countries, waterless urinals could save significant amounts of tap water and reduce discharge to the sewer system. As a result, the design criteria of flow rate could ...
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