New systems are being developed to purify wastewater. One popular experimental system today is the constructed, or artificial wetlands system, which diverts wastewater through an aquatic environment consisting of aquatic plants such as water hyacinths, bullrush-es, duckweed, lilies and cattails. The plants act as marsh filters, and the microbes which thrive on their roots break down nitrogen and phosphorous compounds, as well as toxic chemicals. Although they don't break down heavy metals, the plants absorb them and they can then be harvested for incineration or landfilled.31
According to EPA officials, the emergence of constructed wetlands technology shows great potential as a cost-effective alternative to wastewater treatment. The wetlands method is said to be relatively affordable, energy-efficient, practical and effective. The treatment efficiency of properly constructed wetlands is said to compare well with conventional treatment systems.31 Unfortunately, wetlands systems don't recover the agricultural resources available in humanure.
Another system uses solar-powered, greenhouse-like technology to treat wastewater. This system uses hundreds of species of bacteria, fungi, protozoa, snails, plants and fish, among other things, to produce advanced levels of wastewater treatment. These Solar Aquatics systems are also experimental, but appear hopeful.33 Again, the agricultural resources of humanure are lost when using any disposal method or wastewater treatment technique instead of a huma-nure recycling method.
When a household humanure recycling method is used, however, and sewage is not being produced, most households will still be producing graywater. Graywater is the water that is used for washing, bathing, and laundry, and it must be dealt with in a responsible manner before draining into the environment. Most households produce
sewage (blackwater). Households which compost their humanure may produce no sewage at all — these households are prime candidates for alternative graywater systems. Such systems are discussed in Chapter 9.
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