How to Build a Sand Filter
| By victor | Category: Water
This article explores how to build a Water Sand Filter.
One the most common simple water filtration devices for rural areas is a simple sand filter.
Slow sand filters are very easy to construct and can be built from commonly available materials. They use a medium coarse sand which is similar to the one that builders use for fine concrete aggregate as the filtration medium.
Increasingly sand filters are being sold as filtration package kits for “ready to go off the shelf filtration solutions”.
The slow sand filtration process improves not only the physical characteristics of the quality of water but also a significant in the reduction of the number of micro-organisms (bacteria, viruses, cysts etc) and in the removal of colloidal matter.
These bacteriological impacts occur due to the growth of a thin layer of algae, and bacteria on the surface of the sand bed. This layer is called the schmutzdecke. It is here that these micro-organisms go to work to break down the organic matter.
Cleaning Slow Sand Filters
Whilst their close cousins the ” rapid sand filters ” require cleaning by a complicated backwash procedure, slow sand filters can be easily cleaned by the relatively simple regular removal of the top of the filter bed, including the schmutzdecke.
Slow Sand Filter Design
The dimensions of a slow sand filter should be decided after its mode of operation and output have been established to achieve a filtration rate of about 0.1 m/h.
Preassembled packaged sand filtration kits are increasing in their availablity on the market. These kits allow for a rapid and easy installation of slow sand filtration solutions even in the most remote locations.
The most typical filtration kit is made up from two untreated water storage tanks and two slow sand filtration tanks and approriate pump sets, if required.
Both filter units would be designed to operate in parrallel to facilitate cleaning where one unit would be left in operation while the other one is cleaned.
One of the biggest improvements in slow sand filtration in recent years is the introduction of a synthetic filter fabric which fitted above the top layer of the filter bed. This fabric layer makes it possible to clean the filter without the need to scrape off the upper layer of sand.
The two best articles I have read about how to build a sand filter are located here and here.
