Looking for information about groundwater filtration? This article will help you out. Visser & Smit Hanab, co-developer of the HDDW system, is a specialist in groundwater management and HDDW’s are often used for groundwater filtration purposes.
The filtering of groundwater generally involves introducing a device for the removal of unwanted substances from the water such as dirt, heavy metals, bacteria or harmful chemicals, prior to using the water for direct human consumption or for the growing of food crops that will later be ingested by humans or animals.
The most common groundwater filtration method utilizes a screen filter, recommended in instances when light to moderate contamination is present. Screen filters capture contaminants using a physical barrier that the water is passed through – a screen element –designed with a specific number of holes per linear inch, or mesh size. The larger the mesh size, the finer the screen, and any particles larger than the mesh size cannot pass through the screen and are filtered out.
HDDW for groundwater filtration
When utilizing the HDDW technique, which installs a horizontal ‘well’ along with a filter, groundwater extraction and filtration can be performed simultaneously in one process, providing for the most cost-effective solution possible in most cases. Further savings also is realized as a result of the need for fewer pumps and pipes to be installed.
Another form of physical barrier for filtering groundwater is the disk filter. Similar to a screen filter, it instead uses stackable “disks” to create a three-dimensional filtering apparatus that provides greater surface area to trap debris, a preferable option in situations where filters cannot be easily or frequently serviced.
Groundwater filtration by using sand as a filter
Sand filters are also a popular means of groundwater filtration. Ideal for water containing a high concentration of organic contaminants, sand filter tanks are usually made of stainless steel and filled with a fine silica sand. Water is pumped downward through the sand and the clean water flows out of the tank through a slotted pipe known as an underdrain. This is also the case when an HDDW is placed.
In cases where the water pollutants are “settleable,” e.g., they sink to the bottom of water rather than remain suspended in it, the best groundwater filtration technique is often a centrifugal separator. These employ a spinning action to separate settleable solids from the water.