Rainwater harvesting with Sustainable technology:
A look at the design, construction and operation of a small scale slow sand water filter. (Building a small slow sand water filter for individual use)
The filter that this water has passed through has been in operation for 1 year (as of 2008-12-01) without deliberately disturbing the biolayer (schmutzdecke) for cleaning purposes, with the exception of disruption from freezing in December 2008 and January 2009. During the sub-freezing temps, which lasted through December and January, the biolayer was compeletly frozen. This filter also has a charcoal filter hooked to the output.
These pictures are of water that is run through the filter on an ongoing basis during the rainy season (fall, winter, spring). Simply dumping a bucket of cloudy water into a filter and watching clear water come out is not the same thing. It takes at least several hours for the water that goes in to a well designed slow sand filter to get filtered and show up at the output. The first flush diverter removes concentrated chemical pollutants from the water so the slow sand filter can work on the biological contamination. See the larger versions of these images below.
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The picture above (picture zero - roof water) is water from a composition roof that has NOT been through a first flush diverter. The bucket is a 5 gallon bucket.
The picture above (picture one - pre-filter water) is water from a composition roof that has been through a first flush diverter. The bucket is a 5 gallon bucket.
This is water from the same composition roof as the pre-filter water in picture one, that has been through the same first flush diverter mentioned in the picture one caption after it has been through a small slow sand water filter.The bucket is the same 5 gallon bucket as in picture one.
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