Don't be so caustic!

Magnesium hydroxide ( Mg(OH)2 ) is much better than caustic soda for treating wastewater. Why aren’t its advantages better known?

John Van Wingerden \ March 4, 2021

Treating wastewater from food processing facilities can be so much safer, more environmentally friendly and more cost-effective thanks to a benign but extremely effective ingredient.

One of the primary reasons to treat wastewater is to reduce acidity and to raise the pH level.  Balancing the pH is vital in preventing harm to the environment or to infrastructure such as pipes, storage facilities and land application systems (sprinklers), and to minimize odor.

The best way to neutralize acid in wastewater is to dose with an alkali to maintain a neutral pH level.  The traditional method to treat acidic wastewater involves the use of caustic soda, otherwise known as sodium hydroxide (NaOH).  Other widely used alkalis are soda ash (sodium carbonate) or hydrated lime (calcium hydroxide).

However, all these materials are hazardous and require high dosage rates for them to be effective. Caustic soda is often used instead of powdered alkalis like lime or soda ash because it is easier to handle and requires less maintenance.  Dosing with caustic soda is quite simple, but this dangerous substance must be handled with extreme care, abiding by chemical containment and occupational health and safety measures.

Fortunately, there is an alternative.  An increasing number of food processing companies have switched to magnesium hydroxide to control their wastewater pH levels.  This non-hazardous compound provides an extremely strong buffer to control pH and is more friendly to the environment…

AMALGAM for caustic replacement

A safe and cost effective alternative to the use of sodium hydroxide (caustic soda) for wastewater alkalinity and pH adjustment.

Find out more

A solution to the problems of caustic soda

Fortunately there is an alternative.  An increasing number of food processing companies have switched to magnesium hydroxide to control their wastewater pH levels.  This non-hazardous compound provides an extremely strong buffer to control pH and is more friendly to the environment.  In fact the magnesium ion is a soil nutrient, being the core element in chlorophyll that drives photosynthesis.

John Van Wingerden, Regional Manager of Inland Environmental Resources (IER), said that the product’s popularity is growing because it is not only safer for employees and the environment, but also less expensive than caustic soda in most applications.

“Every gallon of 50% NaOH can be replaced by 0.6 gallons of AMALGAM-60 (IER’s 60% Mg(OH)2) to provide the same pH control and typically a boost in alkalinity.”

IER, a Calix company, is an American manufacturer of patented industrially-sustainable solutions including magnesium hydroxide, which it markets as AMALGAM, for neutralizing acidic wastewater in the United States.

“Traditionally the biggest concern with the use of magnesium hydroxide has been that the product is a slurry that can settle and plug feed pumps.  To address this, we have developed proprietary products with improved settling stability.  In addition, we work closely with our customers to provide optimized agitated storage and feed systems,” Van Wingerden said.

“Caustic soda is great as an industrial cleaner, destroying the organic residue off walls of stainless steel tanks and pipes.  However, those same properties are why caustic soda is not the best choice for wastewater pH control, especially when the goal is to control pH and alkalinity for aerobic or anaerobic microorganism systems that rely on gentle but strong buffering in order to optimize activity and overall performance.  An accidental overfeed of caustic can result in severe and costly damage to a wastewater microorganism population.”

“We are gradually educating plant managers to the cost savings, environmental, and employee safety benefits that can be realized by switching away from caustic soda.  It is our corporate passion to help food processing customers simplify their wastewater treatment processes while saving money, making the job safer for their employees, and improving the environment.”

Since IER entered the wastewater treatment market 20 years ago, magnesium hydroxide usage in the United States has become more popular.  In many ways, this market growth has been driven by an increased emphasis on environmental concerns (primarily salinity issues) and awareness of employee safety concerns (OSHA issues).

The fact that the daily chemical usage cost is also cheaper than that for caustic soda has often been the final deciding factor for food processing plant management to make the switch to this powerful, but gentle, nonhazardous alternative.


Magnesium Hydroxide – safe and cost effective alternative to sodium hydroxide / caustic soda
Disclaimer: This experiment was not performed in a controlled lab environment and is routinely performed safely as a benchtop demonstration to show that magnesium hydroxide provides more CaCO3 equivalent alkalinity on an equal weight basis when compared to caustic soda, which means less chemical consumption and can result in significant cost savings. Magnesium hydroxide is non-hazardous and non-corrosive which makes handling safer and easier.

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