Conventional Water Filtration 

• Sand filter

     Pressure sand filters (PSF) are used in many industrial applications and often are popularly termed rapid sand bed filters. RPSF consists of a pressure vessel that is normally vertical or horizontal, in rare occasions, depending on the layout of the plant. The filter vessels are generally of welded mild steel construction lined with rubber/epoxy. A minimum of 50% freeboard is provided over the filtering bed depth to enable efficient backwash.

• Multimedia filter

     Multi-media filter (MMF) based on the filter bed speed as input. For industrial water filtration purposes vertical filter bed speeds (ideal service flows) varying between 10 m/h and 25 m/h are used depending on the quality of the to be treated water. The higher the total suspended solids (TSS indicated in mg/l) content or the more turbid the water, the slower the vertical filter bed speed. Suspended solids consist of small particles such as silt, clay, grit, organic matter, algae and other microorganisms. Some advanced filtration media can still efficiently filter water at higher speeds, contact us for these applications. In private swimming pool water treatment filtration bed speeds of up to 50 m/hour are used. This is not recommended for industrial applications. Higher flow rates can prevent particles from adhering to the media granules or can dislodge particles that were previously retained. These filters are called multi-media filters because they contain different layers of filtration media ordered in decreasing porosity. Multi-media water filters are able to trap and retain a far larger number of particles (generally down to 10-25 microns) than traditional sand filters before backwashing becomes necessary.

• Carbon filter

     Granular activated carbon (GAC) is commonly used for removing organic constituents and residual disinfectants in water supplies. This not only improves taste and minimizes health hazards; it protects other water treatment units such as reverse osmosis membranes and ion exchange resins from possible damage due to oxidation or organic fouling. Activated carbon is a favored water treatment technique because of its multifunctional nature and the fact that it adds nothing detrimental to the treated water. Most activated carbons are made from raw materials such as nutshells, wood, coal and petroleum. 

 

     Typical surface area for activated carbon is approximately 1,000 square meters per gram (m2/gm). However, different raw materials

produce different types of activated carbon varying in hardness, density, pore and particle sizes, surface areas, extractables, ash and pH.  These differences in properties make certain carbons preferable over others in different applications.

 

     The two principal mechanisms by which activated carbon removes contaminants from water are adsorption and catalytic reduction.  Organics are removed by adsorption and residual disinfectants are removed by catalytic reduction

• Softener filter

     Wells, rivers, lakes and oceans all have different types and levels of contaminants. These contaminants, other than living organisms or turbidity are in the form of dissolved solids. The total dissolved solids are all the salts or minerals contained in the water source. These salts and minerals can be broken down into ions. The positively charged ions are called Cations and the negatively charged ions are called Anions. The hardness ions are primarily calcium, magnesium and iron which are Cations. The hardness in water causes scale to form inside pots and pans, pipes, water heaters or boilers.

 

The Ion Exchange Process

     The Ion Exchange Process Water Softeners remove hardness from water by a process known as ion exchange. The media, called resin; in the softener is charged with sodium (or potassium) ions. When the hardness ions come in contact with the resin beads the hardness ions are collected and the sodium (or potassium) ions are released, thus the term ion exchange. The hardness ions are exchanged for sodium (or potassium) ions. The typical cations found in the raw water are exchanged within the resin bed for sodium or potassium, as shown in the illustration. Normally, when two-thirds of the resin bed is exhausted, the softener will allow hardness to slip through. When this occurs, it is time to regenerate or recharge the resin bed using a salt and water mixture, known as brine. Sodium chloride (NaCl) or potassium chloride (KCl) are normally used for this purpose. Regenerating the resin bed refreshes its ability to exchange ions

 

• De-Iron filter

     The Iron Removal Filters are designed to remove the Excess Iron content present in the feed water with minimum pressure drop.

     Most iron filtration systems operate on the principal of oxidizing the iron (oxidation) to convert it from a ferrous (dissolved or soluble) to a ferric or undissolved state. Once the iron is converted to ferric state, it is precipitated on a filter bed.

     For low Iron content in feed water, the Filter consists of Manganese Zeolite, where the iron is oxidized to insoluble hydrated oxides that are removed by the mechanical filtering action of the Zeolite bed.

Advance Water Filtration

     Microfiltration or Ultrafiltration is a type of physical filtration process where a contaminated fluid is passed through a special pore-sized membrane to separate microorganisms and suspended particles from process liquid. It is commonly used in conjunction with various other separation processes such as ultrafiltration and reverse osmosis to provide a product stream which is free of undesired contaminants.

     Microfiltration usually serves as a pre-treatment for other separation processes such as ultrafiltration, and a post-treatment for granular media filtration. The typical particle size used for microfiltration ranges from about 0.1 to 10 µm.[1] In terms of approximate molecular weight these membranes can separate macromolecules of molecular weights generally less than 100,000 g/mol.[2] The filters used in the microfiltration process are specially designed to prevent particles such as, sediment, algae, protozoa or large bacteria from passing through a specially designed filter. More microscopic, atomic or ionic materials such as water (H2O), monovalent species such as Sodium (Na+) or Chloride (Cl−) ions, dissolved or natural organic matter, and small colloids and viruses will still be able to pass through the filter.

     The suspended liquid is passed through at a relatively high velocity of around 1–3 m/s and at low to moderate pressures (around 100-400 kPa) parallel or tangential to the semi-permeable membrane in a sheet or tubular form.[4] A pump is commonly fitted onto the processing equipment to allow the liquid to pass through the membrane filter. There are also two pump configurations, either pressure driven or vacuum. A differential or regular pressure gauge is commonly attached to measure the pressure drop between the outlet and inlet streams.

     The most abundant use of microfiltration membranes are in the water, beverage and bio-processing industries. The exit process stream after treatment using a micro-filter has a recovery rate which generally ranges to about 90-98 %.