Treatment Technology Comparison: Iron and Iron Hydrogen Peroxide Treatments vs. Technical Grade Magnesium Hydroxide

MODERN UTILITY GOALS FOR ODOR AND CORROSION CONTROL, INCLUDE:

H₂S Prevention and Control
Proven Corrosion Control (raise surface pH of corrodible surfaces)
Added value for plant BNR processes and solids treatment

Several iron, iron catalyst and peroxide treatments have emerged over the years, and all are designed to treat hydrogen sulfide that has already formed in the collection system. These treatments can be classified as:

Iron Sulfate or Iron Chloride treatment
Iron Compound added, and wastewater stream later treated with Hydrogen Peroxide
Iron Catalyst in combination with Hydrogen Peroxide

The purpose of this document is to illustrate the pitfalls, and hidden costs inherent in depending upon iron and hybrid iron, plus peroxide treatments. What may initially appear to be a cost effective treatment strategy will often result in increased costs and can increase corrosion.

Iron and other hybrid treatments often claim that they prevent corrosion by reducing sulfide gas, but only Thioguard can actually result in increased surface pH on pipes and other infrastructure, in addition to reducing hydrogen sulfide gas. Corrosion is a system-wide problem, requiring a system-wide solution. Thioguard Technical Grade Magnesium Hydroxide treatment is a proven, superior alternative, delivering added value throughout your operation.

The following is a quick comparison of Thioguard to three common classes of treatment:

IRON SALTS/IRON COMPOUNDS TREATMENT

When treating with iron salts, what happens to the alkalinity in the wastewater? One pound of iron salts consumes 1.75 lbs. of alkalinity. Every gallon of iron sulfate, upstream of the plant and in biological processes, can result in significant alkalinity replacement costs later on.

Does iron addition prevent corrosion? No, iron compounds are acidic in nature, and will cause or increase corrosion at your plant. In addition, using iron and proprietary catalysts requires eye wash installations and extensive PPE, one more “hidden cost” of using an outdated technology.

HYDROGEN PEROXIDE TREATMENT – A QUESTIONABLE CHOICE50% hydrogen peroxide treatment depends on oxidizing the hydrogen sulfide, and the reaction is immediate. With this kind of immediate reaction, the result is limited longevity. Treatment must occur immediately before the hydrogen sulfide is released to the atmosphere in a wet well, and therefore may require multiple treatments along an extended line.

In addition, peroxide is extremely dangerous and is generally not considered for use in neighborhoods, medians and right of ways, playgrounds, schools or other sensitive areas. Leaks or tank ruptures can cause fires, property damage and danger to people. In fact, hydrogen peroxide has been used by terrorists as an oxidant for explosives!

HYBRID IRON, CATALYST AND PEROXIDE TREATMENTS –
ANOTHER QUESTIONABLE OPTION

These treatments depend on Iron or a catalyst to achieve hydrogen sulfide complexation, followed by peroxide as a strong oxidant to oxidize the sulfide. Some catalyst treatments warn not to combine their product with hydrogen peroxide – due to the potential for an exothermic reaction. Why introduce this kind of a hazard, when it can be easily avoided?

In general, the iron treatments above do little or nothing to prevent corrosion in long sewer lines, and when used for odor control, they simply cannot compare to the long lasting power of Thioguard to deliver consistent, reliable system-wide performance.

INCREASED ACIDITY = INCREASED CORROSION
INCREASED SURFACE pH = INCREASED STRUCTURAL LONGEVITY

In an acidic environment (pH=2), corrosion is rampant, tearing through 2″ of concrete in as little as 8 years. When effective surface pH=4, similar corrosion levels are pushed out to 50+ years.

Thioguard is the ONLY commonly used product that has a direct mechanism to PREVENT CORROSION by raising surface pH. Moreover, the benefits of adding THIOGUARD to your collection and treatment processes are not limited to the prevention or reduction of corrosion. You will also benefit from a reduction in the formation of sludge – significantly reducing your handling and transportation costs.

COMPARISON TO THIOGUARD CHEMISTRY

In contrast, Thioguard does nothing to lower the pH of the wastewater, produces no reaction products that can lead to additional sulfide production, and produces no sludge to settle out in the system or to be dewatered at the WWTP. The reaction is as follows:

The Magnesium binds the sulfide in a similar manner to iron and it will not be released unless the pH drops to 5.5 which is not normal In wastewater. More importantly, Thioguard is preventative and controls the formation of sulfide by increasing the pH and retarding the Sulfate Reducing Bacteria activity.

CHOOSING THIOGUARD WILL:

Decrease Maintenance
Reduce Capital Replacement Costs
Decrease FOG related SSOs and ARV Malfunction
Reduce Overall Costs