How to Choose a Filtration System
When choosing a Filtration system its vital to choose the right filtration media for your water filtration project.
When choosing a filtration system for a particular water treatment project, thorough consideration needs be given to the type of filter(s) and filtration media to be used. The engineering that brings these together, too, is essential in order to ensure successful operation of the water treatment plant.
Being aware of the different types of filters, filter media and filter accessories is important, as this enables one to make an informed decision regarding the selection of a water filtration system.
Types of Filters
There are a variety of filters available for water treatment purposes. The most noteworthy types of filters include cartridge filters, bag filters, media filters, membrane filters, and disc filters.
A cartridge filter is a combination of a housing and a replaceable filter element. The element comes in a variety of forms, either offering more surface area or depth, depending on filtration requirements. Its primary function is the removal of suspended solids of various sizes.
Carbon is also a frequently used compound for chlorine or organic removal.
Larger units are able to hold multiple cartridges, increasing the volume the unit is able to process.
A bag filter is very similar to a cartridge filter in that it comprises a housing and a replaceable filter element.
Bag filters are usually installed for higher volume applications. It is a simple, flexible and cost-effective type of water filter.
Typically, a fiberglass reinforced plastic (FRP) or steel vessel can house various types of filter media, based on the specific application. These vessels can be configured for manual or automated cleaning, depending on the valves used. They can be installed in either a parallel or series configuration, enabling higher throughput and/or various media to be employed to perform their respective functions.
The benefit of media filtration is ultimately that it offers superior depth and contact for improved filtration capacity.
Types of filter media
There are various types of filter media available to use in conjunction with your chosen filter. Filter media is used to remove taste, odour, chlorine and even certain solids in the water supply.
Silica sand: Affordable, widely available filter media that lasts for years and filters particles down to 20 microns.
Zeolite: Microporous crystalline solids that offer a high surface charge density and high cation exchange capacity, and can bind to many materials.
Glass: Crushed, recycled glass removes finer particles from water than sand and tends not to block or channel.
Heavy metal removal: Silica or zeolite that has been coated with manganese oxide, which increases the oxidation potential of the media, assisting in the oxidation reaction of dissolved metals.
Granular activated carbon (GAC): Removes chlorine, chloramines, disinfection by-products and other compounds which impact water colour, taste and odour.
A membrane filter acts as a physical barrier to separate contaminants from water. Membrane filtration is typically employed where fine filtration is required, i.e. microfiltration and ultrafiltration, removing low molecular weight suspended solids – even bacteria and viruses.
Reverse osmosis membranes can also be classified as a type of hyper filter, but its main purpose is to remove dissolved ionic species.
The photo above shows one of AZUD's air assisted DLP disc filters.
A disc filter is a type of water filter that is made of a number of discs stacked on top of each other and mounted on to a central drum. Disc filters are designed for high flow rates as well as increased depth filtration and participle retention capacity.
A differentiating factor between disc filter brands is not only the type of disc to assist with improved filtration but also the cleaning mechanism employed to offer superior backwashing in terms of water and power efficiency.
Like anything in life, it's not just the tool that gets the job done but who and how you apply it to achieve the best result. Some of the important factors to consider include:
Velocity: The velocity or contact time of a filtration system determines its filtration capabilities and in turn performance.
Pipe sizing: Material compatibility, flow and aesthetics are three major considerations to keep in mind when determining the manifold design.
Pump selection: When selecting pumps for filtration systems, one must pay attention to the flow, pressure, material compatibility, and solids handling capacity to ensure optimal operation and life span.
Automation: Automation plays a big role in ensuring important regular activities such as backwashing occur at predetermined intervals or when required, improving plant performance.
Water filtration, being one of the main solutions we offer here at WPS, is a field of water treatment in which our team is highly skilled and experienced. Contact us if you would like to learn more about our filtration services.