Profile: KWI International designs and installs water and waste water treatment systems for industrial & municipal applications. Our KS Filter™ is equipped with a unique double sand backwash device that allows flexibility and reliability in operation. The backwash of the sand is the most important process parameter for this type of filter. The sand is taken from the bottom and is pumped by an airlift into the washing chamber. From there it falls back on the top of the sand bed. The quality of the filtered water depends on the size of the sand and on the sand backwash rate. Therefore the filter is equipped with a sophisticated and carefully sized double backwash facility. This design allows a wide variation and fine setting of the backwash parameters.