Struv-Free Series

Within the water and wastewater industries, scale is a term that represents minerals formed and attached to various substrates or surfaces. In wastewater systems, scale formation begins with the decomposition of organic molecules and cells by anaerobic bacteria. This naturally occurring process generates acids like carbon dioxide (CO2) and hydrogen sulfide (H2S). The presence of CO2 and H2S causes the pH in solution to decrease often between high 4 and mid 5. At this stage, bacteria and enzymes, the presence of common chemicals, and agitation (or lack thereof) make conditions just right for mineral generation.

Among the most common and troublesome minerals within many wastewater applications are struvite (magnesium ammonium phosphate), vivianite (hydrated iron phosphate), and inorganic carbonates (salts of carbonic acid). In the past, treating scale formation included methods like line excavation and replacement, strong (HCL) acid washing, or even jet-washing. Today, Guard Products is empowering industries with new solutions that showcase safety and efficiency in the removal and prevention of mineral scale formation.


The Struv-Free Series is designed to deliver two options for municipal, agriculture, and biogas wastewater applications: scale deposit removal and scale formation prevention. The blends in the Struv-Free Series target various mineral scales such as struvite, vivianite, and inorganic carbonates. The Struv-Free Series products ship non-hazmat and are readily biodegradable. For safe, efficient, and economical scale treatment solutions, select from the following products.


ST-2520 is designed to efficiently remove the struvite mineral scale and can be safely applied by workers as it is a modified mild organic acid. ST-2520 has not demonstrated to be corrosive on infrastructure or equipment in application and works quickly on the most difficult to remove deposits. Predictable reaction rates make planning and cleaning faster and simpler. 

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ST-2320 is designed to remove vivianite and carbonate scales. It is safe to handle in application as a modified mild organic acid and has not demonstrated to be corrosive on infrastructure or equipment in application. Typical carbonate scale removal rates with ST-2320 are rapid.

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ST-FOAM is designed to remove mineral scale deposits in applications where direct liquid contact and saturation is impractical. ST-FOAM's adhering head provides good contact time when applied to scale deposits in various settings and is an excellent choice for headspaces, parts, belt presses, and other difficult to treat equipment.

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ST-2600 is a mixed organic acid product which can remove scale deposits and also be applied in ppm feed rates to inhibit the growth of scales.

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ST-2650 is a polymeric dispersant blend designed to singularly and effectively control scale formations in low ppm application levels.

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Lines Between Anaerobic

Digestion & Dewatering

Lines From Dewatering

To Disposal / Landfill

Return lines

(to headworks)

Parts, pumps, valves,

tubulars, digesters

Discharge Lines

(to Holding and Lagoons)

Urinals, showers,

sinks, toilet bowls


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