Sul-Free Series

Odor Generation in Wastewater Treatment Applications

In many industries, organic compounds are referred to as a food source for bacteria. This description can help to explain the relationship between bacteria and compounds, as well as the products their interactions generate. Wastewater applications deal with this naturally occurring process every day. However, some of the common products (in this case- odors) can be severely irritating to people and even dangerous to their safety. A few of the common breakdown products in various wastewater applications include the acid gases of CO2, sulfides, and mercaptans (longer carbon chain odorous sulfur compounds). Of these products, sulfur compounds are the greatest of all odor-causing contributors.


Broken down sulfur compounds release hydrogen sulfide (H2S), the most problematic and dangerous of acid gases. H2S is a highly toxic safety and regulatory issue, a source of corrosion that damages infrastructure, and a major source of odor complaints. Typical scavenging compounds for H2S removal have fallen into four groups: 

  • Organic amine/imine based
  • Metallic oxide / salt based
  • Caustic based
  • Oxidizers


The Sul-Free Series is a new and flexible application group of products that fall into the amine / imine based category. These blends offer many advantages over older sciences that have been used up until now. Each Sul-Free Series blend is designed to solve the issue of Hydrogen Sulfide (H2S), mercaptans, and VOC’s rapidly and selectively. The Sul-Free Series does not donate solids to systems unlike many traditional treatment methods. All Sul-Free Series blends are rated non-hazmat, safe to handle and use, and flexible in application.

Sul-Free Series can be used very successfully in misting / fogging, pump / meter injection, and scrubbing / bubbling applications. Sul-Free Series can be used in digester applications to control H2S generation in lieu of traditional ferric salt use. Ferric salt use can add up to 10% of solids loading which is a cost in dealing with bio-solids treatment. 

Sul-Free Series demonstrates the ability to control H2S while encouraging beneficial bacterial activities to increase- shown by increases in dissolved oxygen.

Sul-Free Series captures noxious compounds and begins reacting within seconds and also works well with feed systems tied to on demand volume adjustments.

Guard Products now offers Sul-Free Series GT- 615 and GT-650. These two blends are designed to quickly and selectively scavenge H2S, mercaptans, and VOC’s in wastewater, wastewater emulsions, and hydrocarbon streams. In addition to GP’s new GT-615 & GT-650, Guard Products now offers the Gas Taxi Series- exclusive low pressure mobile and skid scrubbing units. Gas Taxi scrubbers are available in standard or custom models, do not require power, pressure or traditional medias to operate, and are designed to work with GP’s patented Sul-Free Series blends.

Scavenging Applications

  • Headworks Injections
  • Digester Vent Gas / Exit Pipe & Effluent Lines
  • Manhole Treatments
  • Lift Stations (FOG & H2S)
  • Collections & Anaerobic Systems
  • Holding Tanks / Ponds / Lagoons
  • Wet Scrubbers
  • Dewatering Applications
  • Bubble Towers
  • Downhole Operations
  • Refining
  • Bio Gas Streams
  • Remediation / Landfill

Sul-Free Series Products

  • WS-1500 - Concentration of general use scavenging system
  • WS-1530 - Concentration of general use scavenging system
  • WS-1560 - Concentration of general use scavenging system
  • WS-1585 - Concentration of general use scavenging system
  • Bio-Sul - Concentration of scavenging nutrient replacement system
  • Sul-FOG – Concentration of fat, oil, and grease scavenging treatment system.
  • Sul-POWER - Concentration of general use system degreaser, cleaner, scavenger
  • GT-615 – Concentration of scavenger system for wastewater, wastewater emulsions, & hydrocarbon streams.
  • GT-650 - Concentration of scavenger system for wastewater, wastewater emulsions, & hydrocarbon streams.


Guard Products' Gas Taxi Series includes exclusive scrubbing units designed for low-pressure vent gas / exit pipe operations. Their simplistic and effective design provides optimal performance and longevity. No power or pressure is required to operate the Gas Taxi scrubbers. Gas Taxi scrubbers are designed to work synergistically with GP’s Sul-Free Series blends thus replacing traditional inefficient scrubbing medias.


  • Gas Taxi 160 - Designed for 160 cubic feet per minute flows
  • Gas Taxi 500 - Designed for 500 cubic feet per minute flows
  • Gas Taxi 1800 - Designed for 1,800 cubic feet per minute flows
  • Gas Taxi 3600 - Designed for 3,600 cubic feet per minute flows


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