Grey Water Treatment Marsh
Water from the sinks and shower is reused on the lawns and ornamental plants following treatment in the greywater marsh. The primary treatment tank filters out large particles such as hair, grease, and food scraps.
[Click the image above for a full sized view of the display]
There are two different marsh set ups at the Campus Center for Appropriate Technology. The original design consisted of an open channel filled with vegetation, the newly constructed design consist of a gravel filled channel planted with vegetation. Both designs utilize mechanical and microbial filtration.
The original design of an open channel marsh had some problems. These problems included; stagnant water, rotten smells, dying vegetation, and mosquitoes. In this design the water is allowed to flow into the marsh system by gravity. Once into the marsh the plants surface area is used to remove the unwanted pollutants. Its flow is primarily horizontal (side to side) with baffles placed between each cell to allow the water to be drawn off the bottom of one cell and enter the top of the next cell
The newer design has replaced this open channel of water with a gravel filled channel that the water flows through. In this system the flow is not only horizontal, but also vertical (up and down). Water is gravity fed to the top of the gravel surface and is allowed to penetrate down through the gravel. As the water is penetrating the gravel filled chamber, it also is allowed to move side to side towards the end of the channel. Once it reaches the end of the channel the water is removed from the bottom of the marsh by a perforated pipe that then enters the top of the next gravel marsh box. The purpose of removing the water from the bottom and letting it enter on the top is to allow for oxygenation of the water when it is forced to the surface. This new design does not have as many of the problems that were associated with the open channel design.
Both designs require periodical maintenance. The mechanical filter, or screening device, needs to be checked and cleaned on a weekly basis. The settling tanks have to be emptied and cleaned approximately three times a year. The vegetation within the marshes need to be cut back on a yearly basis, and at some point the gravel in the gravel marshes will need to be removed and cleaned. Besides the operational maintenance required to run these types of filters, very little energy is needed. The people at CCAT only use phosphate free natural detergents and shampoos and no bleach or other household cleaners.
Grey Water Marsh
By Stacy (Spring 2002)
[ Home | Calendar | Contact | CCAT News | Support CCAT | Site Feedback | Search ]