Do Industrial Facilities Need to Remove Silica from Feed Water and Effluent?

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Among all the contaminants that can pose operational challenges to your industrial facility, silica, in its many forms, can be one of the most difficult to remove, especially if that silica is colloidal (meaning the silica particles are so small that they can be widely dispersed). Since silica is commonly found in industrial source water, process water, and wastewater streams, you might be wondering, “Do industrial facilities need to remove silica from feed water and effluent?

In this blog article, we’ll explore some of the reasons why industrial facilities might want to consider removing this problematic contaminant at these different parts of the industrial process so you can get a better understanding of the potential problems this compound might cause if it’s not taken care of properly. If you’d like to learn more about how to remove silica, see our recent blog article here. First, let’s take a look at what silica is and where it’s found.

length of piping at treatment facility

What is silica and where is it found?

Silica, or silicon dioxide (SiO2), is one of the most abundant elements found in the earth’s crust and is generally always present in a facility’s raw water intake. Silica is found in higher concentrations when dealing with groundwater (as opposed to lower concentrations in surface water) and naturally occurs in many forms, such as crystalline (as it appears in quartz), amorphous (as it appears in opal), or mixed in with other elements (as it appears in sand). This element is mostly found in quartz, however, and is generally considered one of the more complex mineral families because there is such a large variety of compounds. This element is also synthetically produced, as it is commonly used in industry to make certain products, such as concrete, abrasives, electronics, and glass.

Does your industrial facility need to remove silica from its feed water?

Since silica can accumulate on machinery surfaces and cause hard mineral deposits known as scale, many facilities work to remove this contaminant before it causes production issues. Scaling is a deposit formed on the inside of piping and heat transfer surfaces when the water is heated and impurities precipitate or settle out. These deposits can build up and interfere with heat transfer or, in extreme cases, cause tube and system failure. 

For example, if a power plant is drawing their process water from a river or lake, there could potentially be an assortment of suspended and colloidal solids present, including silica. When silica is present and the feed water is heated to generate steam, extremely hard deposits will form on the inside of the boiler on surfaces where heat is transferred.  

Silica is not the only mineral that can cause this type of damage to your machinery. In addition to iron, calcium, magnesium, and aluminum, silica is just a portion of the contaminant problem. The level of scaling your boiler and other system parts exhibits will depend on the amount of these impurities present in your feed water in relation to the pressure and heat at which your machinery operates. For example, many higher-pressure boilers will require a higher quality of water with less contaminants and silica present than some lower-pressure boilers, because at higher pressure, more silica will begin to lodge and form scale on the moving parts, causing system upsets and ultimately failure.

Silica can also cause membrane fouling in nanofiltration and reverse osmosis systems, or other membrane filtration units. Membrane fouling occurs when silica particles lodge in the membrane’s pores, obstructing the normal flow of liquids through the membrane. Additionally, because silica particles are abrasive, they can also cause premature tears and weakening of delicate filtration membrane materials.

Does your industrial facility need to remove silica from its wastewater?

One reason your facility might need to remove silica from its wastewater is because many effluent limitations include some kind of guideline on the level of total suspended solids (TSS) or total dissolved solids (TDS) your facility is allowed to discharge. TSS, or the organic and inorganic solid material suspended in the water, can harm aquatic life when present in high concentrations in wastewater. TSS can decrease levels of oxygen in aquatic environments and kill of insects. They can also scale and foul piping and machinery.

TDS are any anions, cations, metals, minerals, or salts found in water and wastewater. They can cause issues with aquatic life, irrigation and crops, and they can also seep into groundwater. TDS can be generated in wastewater from just about any industry, and it also includes silica. Follow your local and federal regulations for the amount of silica in your effluent to ensure you’re meeting the mandated limits.

Another reason your facility will need to remove silica is that it is planning to reuse its wastewater for process water. For all the reasons you wouldn’t want to leave silica present in your feed and process water streams, you wouldn’t want the mineral in your recycled water feed, either. Removing silica will mitigate membrane and system fouling and scaling, which can impede your production process.

Can SAMCO help?

SAMCO has over 40 years’ experience in identifying appropriate silica removal technologies to help lower costs and improve system efficiency. For more information or to get in touch, contact us here to set up a consultation with an engineer or request a quote. We can walk you through the steps for developing the proper solution and realistic cost for your particular silica removal needs, or your larger raw water treatment needs.

To learn more about SAMCO’s innovative solutions, visit our page on raw water treatment technologies here.

If you want to learn more about silica removal, these other articles might be of interest to you:

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