Physical Water Treatment Methods
The purpose of industrial water treatment is to eliminate unwanted impurities from water. There are several different methods of water treatment; these include biological processes, physical equipment, and chemical treatment. This webpage focuses on the various methods of physical water treatment. Physical water treatment typically consists of filtration techniques that involve the use of screens, sand filtration or cross flow filtration membranes.
- Screens: Typically used as a pretreatment method to remove larger suspended material.
- Sand and/or Multi Media Filtration: Frequently used to filter suspended solids. Smaller suspended solids and dissolved solids are often able to pass through these filters, requiring secondary filtration.
- Membrane Filtration: Utilizes barrier (microfiltration, ultrafiltration) or semipermeable (nano or reverse osmosis) membranes to remove suspended solids and total dissolved solids, respectively.
Glauconite is a mineral commonly referred to as green sand and is used in greensand filtration. It is an effective filtration medium for the removal of dissolved iron, hydrogen sulphide, and manganese from water. Glauconite is coated with manganese oxide, which causes soluble iron, manganese and hydrogen sulfide gas to bond with oxygen. Bonding with oxygen causes the previously dissolved elements to precipitate and become embedded in the greensand filter. Learn more about greensand filtration for industrial water treatment.
Multi Media Filtration (MMF)
Multimedia filtration is a modern physical water treatment technique that uses at least three different layers of filtration media, typically anthracite, sand and garnet, to filter water. This filter arrangement allows for larger particulates to be trapped at the top of the filter while smaller particulates are trapped deeper in the media. Suspended solids, including: clay, algae, silt, rust, and other organic matter are removed as the water passes through each layer of media. This filtration method is capable of removing particles from 10 to 25 microns in size. Multi media filtration does not remove viruses, bacteria or smaller protozoans. Learn more about multi media filtration for industrial water treatment.
Unlike greensand and multimedia filters, microfiltration uses a barrier membrane to filter very small suspended solids from water. Microfiltration membranes are typically capable of removing contaminants ranging from 0.1 to 10 microns in size. This form of physical water treatment is ideal for removing suspended solids, algae and protozoans from water but does not generally remove bacteria and viruses. Microfiltration does not remove dissolved contaminants from water. Learn more about microfiltration for industrial water treatment.
Ultrafiltration is a physical water filtration process that utilizes pressure to separate solids from water through a barrier membrane. This filtration process is capable of removing suspended solids, bacteria and certain viruses ranging from 0.005 to 0.01 micron in size, and is sometimes used as a pretreatment method upstream of reverse osmosis. Ultrafiltration cannot remove dissolved solids. Learn more about ultrafiltration for industrial water treatment.
Nanofiltration works similar to ultrafiltration, but utilizes a semipermeable membrane with an even smaller pore size. Nanofilters are capable of removing bacteria, viruses and divalent and multivalent ions (e.g. calcium, magnesium). It functions as a barrier membrane capable of removing particles ranging from 0.005 to 0.001 micron in size, and also acts as a semi-permeable membrane capable of removing ions. Due to its ability to remove divalent ions such as calcium it is sometimes referred to as the "softening membrane". Learn more about nanofiltration for industrial water treatment.
Reverse osmosis is one of the most common physical water treatment methods employed in industrial water treatment. Reverse osmosis, also known as RO, filters contaminants out of water using applied pressure to force water through a semipermeable membrane. RO is capable of removing impurities such as dissolved ions (e.g., sodium), bacteria, viruses, and other contaminants ranging from 0.005 to 0.0001 micron in size. Learn more about reverse osmosis for industrial water treatment.
The most effective water treatment systems make use of a combination of biological, chemical and physical water treatment methods, as well as appropriate pretreatment and post-treatment methods to produce water that is free from unwanted contaminants. For assistance in determining the most appropriate water treatment system for your needs, contact the WaterProfessionals®!