Sewage, Water and Waste

There are many attributes that contribute to the overall synergistic success of an ecovillage. In dealing with issues like sewage, water and waste one is left with the question of how to deal with these matters in a sustainable fashion. Many rural ecovillages are connected to the local towns sewer main or have a biological means of breaking down wastes via microorganisms , obtain and collect water from local sources or rain and deal with waste by recycling, reducing, reusing and composting. In an urban setting, things are a bit more difficult. For example a city like Philadelphia has thousands of row homes interconnected throughout the city. If a particular community were to establish sustainable systems of the aforementioned aspects, how would they go about doing so? What are the boundaries from one community to the next? Who can implement, regulate and maintain such systems?

These and many of questions will be addressed throughout this blog in posts to come. But first it is important to mention the what kind of technologies exist and how to apply them to an urban setting in a practical way.

Many ecovillages have self-sustaining systems which break down sewage and excess water. There are two types of waste water; Black water and gray water. Black water is waste water that contains fecal matter (sewage). It is very difficult for it to break down in a natural setting however, much thought has been put into how to develop a sustainable means of dealing with it. With all the energy/materials cost put into sewage transport and purification processes, it would be more logical to have the sewage system local. Technologies such as "reed-bed technology" or sewage gardens are a sustainable, autonomous solution to the problem. Reed bed systems work as followed

"Reed beds use common reed plants (phragnmites communis, a second cousin of the common marsh plant) to dewater solids in a confined area. The beds can be any shape to accommodate existing land conditions and areas. Specially designed ponds with underdrains covered by a sand and gravel mixture are constructed and filled with reed plants. Modified sludge drying beds also work well and are an ideal retrofit. They already have side walls, layers of sand and gravel, an underdrain system which collects and carries away filtrate, and an impervious membrane liner. Solids are pumped into the reed beds. Dewatering occurs through evaporation, plant transpiration, and decantation. Decanted water seeps through the bottom of the bed and through the layers of sand and gravel into the underdrains, traveling back to the wastewater treatment plant for secondary treatment. During dewatering the solids change from liquid to "cake." Six inches of solids and water will compress to a half inch of solid cake. The cake is left in the bed and the process is repeated. Sludge reed beds are a significant improvement over existing drying beds. Sludge can be dewatered and converted into biomass and a low-grade compost without chemical addition or energy. They have lengthy turnover time and are capable of reducing sludge volumes by up to 95% over time."

The technology is innovative, however in an urban setting spacial issues would present an indefinable challenge. Also it may be difficult to implement based on zoning laws, income levels, social participation and willingness to accept.

The second, more feasible type of water treatment is with gray water. Gray water is the water left over after showering, doing laundry and dish washing. It is ideal for houses to be equipped with two sets of drainage pipes: one for black water and one for gray so each can travel separately for further treatment without unnecessary mixing. A filtration system would be needed to filter out soaps, shampoos, etc... The benefits of collecting grey water are beneficial and less energy intensive. It can be used to water plants, to clean, brush teeth, etc... The hardest part of implementing such a system would be financing, design, maintenance, and government approval.

The technology is there but many hurdles keep it's implementation small scale. It is slowly catching on. More posts to come.....

Sources:
http://www.lagoonsonline.com/reedbeds.htm

Barton, Hugh. Sustainable Communities The Potential for Eco-neighbourhoods. Minneapolis: Earthscan Publications Ltd., 2000.

Walker, Liz. Ecovillage At Ithaca Pioneering A Sustainable Culture. New York: New Society, 2005.