Best water treatment suppliers standard supply – Pressure Sand Filter

Sand filtration is frequently used by best water treatment suppliers and are very robust method to remove suspended solids from water. The filtration medium consists of a multiple layer of sand with a variety in size and specific gravity. Sand filters can be supplied in different sizes and materials both hand operated or fully automatically.

Raw water pump is used for generating necessary operating pressure in the pressure sand filter. Raw water is passed through Sand Filter at a pressure of 3.5 kg / cm2 to reduce the suspended solids present in the raw water. The filter will effectively remove up to 30 – 50 microns of the suspended solids to less than 5 ppm. The filter will have to be washed with raw water for 20 to 30 minutes daily. To filter the partials below 30 – 50-micron cartridge filter is used.

Best water treatment suppliers use the following

Graded silica quartz sand and anthracite supported by layers of graded underbed, consisting of pebbles and gravels, are provided with a water inlet at the top. Incoming water is distributed uniformly throughout the cross-section of the filter to ensure that there are no preferred fluid paths where the sand may be washed away and jeopardize filter action. The bottom drainage system is kept to collect filtered water.

The selection of the sand’s grain size is important because smaller sand grains provide an increased surface area and, consequently, more decontamination at the water outlet that, on the other hand, demands extra pumping energy to drive the fluid through the bed. In an attempt at a compromise, grain sizes are generally selected in the range 0.5 to 1.50 mm. A sand bed depth of ∼0.5 to 2.0 m is recommended regardless of the application of which the ratio of quartz sand and anthracite is ∼7 to 50.

During backwash, the sand becomes fluidized and the expansion in volume may go up to about 30%, which allows the sand grains to mix, and the particulate solids are driven off as they start rubbing together. The smaller particulate solids are then forced out with the backwash fluid. The fluidizing flow requirement is typically 5 to 30 m3/hr/m2 of filter bed area, depending on the depth of the bed, for a short period (i.e., for a few minutes only). The filter backwash fluid is taken to a common inlet chamber of raw water pumps. The backwashing process would cause sand loss though not significantly noticeable, thus requiring periodic top up of sand in the bed.

Depth Filters

The most common depth filter is the sand filter, used for water purification. (Stevenson, 1993). Sand filters range in size from very large tanks or boxes used for municipal Best water treatment suppliers  to small portable vessels used in swimming pools. In open sand filters, water flows by gravity through a thick bed of sand or other particulate material.

In the so-called “fast sand filters,” high filtration rate is achieved due to the moderate depth of the sand bed. Flocculants are usually added to the water before filtration. When the bed becomes too contaminated, it is cleaned by reversing the flow (backwash). A rapid upward flux of water lifts the bed and removes the flocks entrapped between the sand particles. In slow sand filters, used mainly in municipal Best water treatment suppliers , the sand bed may be 1.5- to 2-m deep. Due to the slow flow rate, a thin slimy layer of biomass forms on top of the sand. This layer contributes to the purification of the water, acting as a biofilter, but when it becomes too thick it is mechanically removed to restore flow rate. Additional purification effects can be achieved by incorporating adsorbents in the filtering bed. Thus, coating the sand particles with graphite oxide provides a filter capable of removing mercury traces from water efficiently.