Multi-media filters successfully and consistently remove suspended solids from water. During this filtration process, water flows through layers of media such as anthracite, quartz (sand) and garnet in a vessel. These layers are arranged in order of decreasing porosity, which allows larger particles to be trapped in the higher porosity layers while the smaller particles are caught in the lower porosity media. These types of filters are effective in removing particles as small as 2 microns. Pretreatment with polymers and coagulants can enhance performance by agglomeration (bringing smaller particles together to form larger particles). Click to learn more

Carbon filtration utilized activated carbon to adsorb organic material and certain oxidants such as chlorine. Activated carbon comes in three basic forms: powdered, granular and solid. The effectiveness of adsorption is dependent upon the constituent being adsorbed and the type of carbon used. Isotherms or adsorption models are available, which can provide the adsorption characteristics of various compounds for a given type of carbon. Once the carbon has reached adsorption saturation, it is typically regenerated at a regeneration facility.

Green sand filters are primarily utilized for removal of hydrogen sulfide and oxidizable metals such as iron and manganese. The green sand is a glauconite sand, which is typically coated with potassium permanganate. When iron and manganese come in contact with the media, the higher oxides of the manganese oxidizes the iron and they become trapped in the green sand. Hydrogen sulfide is oxidized to an insoluble sulfur precipitate for capture in the green sand. These filters are then backwashed and regenerated with a weaker manganese solution.

Bag and cartridge filters utilize woven mesh of typically polypropylene or polyester felt of a specified micron size. These filters are secured in housings and are disposed upon saturation. The bag-filter system removes particles and colloidal matter from the feed water stream prior to Reverse Osmosis (RO) systems. These contaminants cause RO-membrane fouling. The prefilter housings contain bags of various materials, lengths, and particle-removal capabilities. Click to learn more

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