While Nitrates and Iron have been a common part of the odor control landscape in the past, the growing emphasis on nutrient treatment and resource recovery have made Thioguard technical grade magnesium hydroxide a more compelling and cost effective alternative. Calcium Nitrate products are typically used in many of the nation’s wastewater collection systems, and are used for one thing odor control. Unfortunately, there are multiple costly unintended consequences with the use of nitrate products. In addition, while nitrate use may temporarily address H2S odor problems, nitrate products are of little or no use in combatting corrosion, which is a tremendous problem, both in-plant and throughout every segment of wastewater treatment infrastructure.
NITRATE USE ENCOURAGES
UNWANTED BIOCHEMICAL REACTIONS…
where you don’t want them to occur.
Think denitrification…which consumes organics, and produces nitrogen gas N2 and carbon dioxide CO2, all seemingly innocuous by-products of Calcium Nitrate’s intended use as an odor control technology…but let’s take a closer look…
- Nitrates upset the Bio-P process at your plant
The use of nitrates in the collection system alter the chemical and biological conditions of the collection system, which would otherwise facilitate the formation and transport of VFAs to the treatment plant, where they can be used by PAOs in Bio-P processes.
As VFAs (Volatile Fatty Acids) are eliminated with calcium nitrate addition, VFAs are therefore not available for PAOs (phosphorus accumulating organisms) for phosphate removal at the wastewater treatment plant.
- Nitrates contribute to the formation of F.O.G.
The addition of nitrates contributes to the accumulation of an odorous film, often referred to as a F.O.G. (Fats, Oils and Grease) mat in pumping stations and at your plant. Blockages associated with F.O.G. have been shown to be the greatest contributors to O&M costs including energy consumption, maintenance costs, and Sanitary Sewer Overflows (SSOs).
- Nitrates contribute to Gas Binding in the Collection System
The transfer of wastewater can result in the release of gases such as O2 – Oxygen, CO2 – Carbon Dioxide, N2 – Nitrogen Gas, H2S – Hydrogen Sulfide, CH4 – Methane, VOCs – Volatile Organic Compounds, and VOSCs – Volatile Organic Sulfur Compounds, among others. Some of these gases are drawn into the system through pumping and ventilation, while others are generated within the system either chemically or biologically. These gases can result in the development of gas binding in the system, and are dramatically exacerbated with the utilization of calcium nitrate.
- Nitrates negatively impact conventional processes
The addition of nitrates is not an exact science, and unfortunately, every step along the way there are costly unintended consequences. Add too little, and you’re facing odor problems. Add too much, and you’re faced with the formation of unwanted bubble-forming gases (N2 and CO2 from denitrification) in your settling tank, exactly where you DON’T WANT IT, continuing the formation of F.O.G. mat, (as well as creating an environment unfavorable to your biological processes). This often results in increased metal salts usage or increased polymer usage and associated increases in costs.
NITRATE ADDITION REQUIRES MULTIPLE FEED LOCATIONS, THIOGUARD ONLY REQUIRES ONE
Calcium Nitrate has a short half-life in sewers, and therefore many addition locations are required to achieve adequate system-wide control. This requires several addition locations, and corresponding higher costs and operational oversight. In contrast, a single Thioguard Feed Unit can often replace several nitrate feed stations, and maintain a relatively constant pH level throughout.
THIOGUARD HELPS PREVENT CORROSION
Maintaining a constant surface pH of 6-8 can reduce the rate of corrosion by as much as 100X. The cost of simply ignoring this problem is monumental and Thioguard is the only commonly used product that has a direct mechanism to increase surface pH and prevent corrosion.