Agricultural Filtration: types of filters

November 2021

Reliable water supply is essential to the success and productivity of agricultural irrigation projects. Irrigation systems have evolved significantly over the years to minimise blockages and downtime caused by fine particles in irrigation water blocking up or breaking the entire irrigation system.

Think Water is a respected water filter supplier who understands the need to mitigate against downtime caused by blockages and the resultant inefficiency. We design industrial filtration systems which result in less downtime and greater efficiency.

Water filtration system design is quite an involved process. Firstly, effective water filtration design requires a good understanding of the source of the water – the starting point. It is then essential clear outcomes are established. This might be as simple as, “stop my sprinklers  from blocking up” or more involved such as, “improve the water quality and efficiency of my irrigation system!” The design process in agricultural filtration should build on the starting point and objectives, taking into consideration the various filtration options available to use as part of the overall design solution.

Sand Filtration

Sand filtration is the oldest form of water filtration known and a form of media filter, with evidence found in Roman times showing sand was used to filter water for human consumption. These early beginnings have led to an understanding that the quality of filtered water will depend on the medium used to trap fine particles. Sand filters are still used today to treat wastewater naturally.

Media filters

Media filters are used to filter out fine, unwanted particles from the water. The type of media used will depend on the type of substance being filtered. The media could consist of various resins, carbon steel filters or even chemical filters. Sandstorm Media Filters by Netafim are a trusted irrigation filter used by Think Water when designing irrigation filtration systems.

Gravel Filters

The type of gravel media used will depend on the substance being filtered. Commonly used materials include crushed basalt, crushed granite and crushed silica. The size of the medium will also vary to suit the application. Gravel filters work by allowing unfiltered water to pass through a bed of aggregate which captures unwanted particles suspended in the water inside a pressurised tank. The unwanted particles are captured in the aggregate while allowing the filtered water to progress through the irrigation system.

Screen Filters

Screen filters consist of woven stainless steel mesh, polypropylene, nylon or polyester that create a filtration barrier preventing solid and fine particles from moving through the irrigation system. Different mesh sizes are used according to the substance that needs to be filtered. Fine filamentary algae, for example, would be able to pass through most screen filters. Consequently, the application of screen filters is quite targeted. When suitable they do provide a very cost efficient filtration solution. Our team at Think Water will be happy to help you work out the best type of filtration system for your needs.

Disc Filters

More recent to the agricultural market is disc filter technology. Disc filters consist of a stack of grooved discs that the water circulates through. The grooves on disc filters can be calibrated to suit specific levels of filtration, typically in a crisscross pattern to replicate the succession of filter traps found in fine sand.

SpinKlin Nova by Amiad Water Systems, purports to be “the most advanced, high-performance disc filtration system, combining superior design, maximum flexibility and scalability.The modular, polymeric self-cleaning Spin Klin™ NOVA has a patented breakthrough design for minimal flow interference and provides up to 80% lower head loss and the highest level of efficiency. Spin Klin™ Nova is redefining filtration. This unique filter allows combining several units to accommodate higher flow rate demands, while maintaining a compact footprint. Spin Klin™ NOVA offers unparalleled high-performance with outstanding filtration results.

Ultimately, the choice of which type of irrigation filtration system revolves around the best outcomes, balancing irrigation filter costs, overall filtration design and long term effectiveness. Think Water can help you identify the best filtration solution for your irrigation system, giving particular consideration to the water quality and the substances you need to filter. Give us a call or pop in and see us at one of our many locations.

Filter Cleaning

Once the particles have been filtered out of the liquid they will need to be periodically removed from the filter to maintain peak filter operation. The filter may utilise manual, semi automatic or automatic cleaning.

Manual

Manual filters usually have a pressure gauge on the inlet to the filter that indicates when the filter requires cleaning. A filter blocked with collected debris will cause an increase in pressure on the supply side as the filter becomes full of debris or blocked. As the name indicates the filter will require manual cleaning by the operator. Think Water suggest a system using a manual filter have a regular cleaning program scheduled. Many manual filters can be upgraded to automatic or semiautomatic. The Amiad range of filters can be upgraded to semi-automatic by adding Brushway or Scanway assemblies. Amiad is a preferred supplier at Think Water.

Semi Automatic

Semi automatic screen filter assemblies are an accessory that can provide a quick and efficient way to clean manual filters. The filters can be easily accessed for cleaning. Semi automatic screen filters usually feature a warning mechanism to indicate the filter is blocked and needs manual cleaning. An example of this mechanism is the red warning button that pops up on Amiad screen filters.

Automatic

Automatic screen filters are available in both electric and hydraulic models. They feature a self cleaning function that allows continuous operation without the need to stop for cleaning. Investing in an automatic screen filter prevents downtime and increases efficiency. In larger applications they provide a very cost effective filtration solution.

Other preferred suppliers of automatic screen filters  include Triangle WaterQuip and Netafim.