Ferric Chloride Risks and Alternatives

Coagulants are used in the first step of water treatment; they destabilize the water so micro flocks can begin to form. This is followed up by a polymer, which turns it into a larger flock by creating a bigger charge. Ferric chloride is a widely used “commodity chemical” coagulant that has been around for a long time. Do you know if it is the best solution for your wastewater treatment plant? 

Why is ferric chloride so commonly used?

It often comes down to price and the age of the wastewater treatment plant. Some water treaters simply aren’t aware of alternative products, the plant was initially built to use ferric chloride and has since then used it. One of the main advantages of Ferric chloride is its wide range of operation, making it easy to sell for commodity chemical suppliers. Nonetheless, there is often more performant and cheaper solutions that Aquasan can explore with you. 

Pros and cons of ferric chloride

While not an exhaustive list, here are some important positives and negatives to consider about Ferric:

Pros of ferric chloride

• There is no pH requirement; it works over a broad pH range. And it’s easy to use.
• Is very effective at removing some specific metals.

Cons of ferric chloride

• Ferric chloride is extremely corrosive. Special piping, storage, and pumping equipment are required because it could potentially corrode trough. Some common pieces of equipment that usually contain stainless steel components are flowmeters, level sensors, or automation components which the ferric chloride could eat through. These small components are often the greatest risk for leaks and spills
• The price can fluctuate. The components used to make ferric chloride, (spent iron liquor or hydrochloric acid, the two most common base elements), go up and down quite a bit in price, which can greatly affect the price of ferric chloride itself. Currently, ferric chloride users are facing cost increases potentially as high as 40%. 

Health and environmental risks of ferric chloride

• Ferric chloride is a coagulant that comes with many hazards statements such as “Causes severe skin burns and eye damage” as well as “Toxic to aquatic life” and “May be corrosive to metals”. 
• Due to the high corrosivity of ferric chloride, there is an increased risk of spills and handling hazards. In the best-case scenario, all equipment will be stained, in the worst, serious injuries can occur. 
• Due to the nature of production of ferric chloride, many metals and heavy metals are present in the final product.  Zinc, manganese, and chromium are often found in relatively high concentration in Ferric chloride. 

What are some substitutes for ferric chloride?

Substitutes include other aluminum and iron salts, like sodium aluminate and ferric sulfate or alum, but these may or may not work. Speciality products, instead of commodities, may offer a better solution. Aquasan offers a wide range of products to reduce handling hazards, increase environmental stewardship while also increasing economical performance. 

If a water treatment plant is using ferric chloride, a recommended replacement product is AQ-8921. This product is not only a successful replacement but also offers a much better quality of water and safety for employees for the same dollars spent. AQ-8921 removes much more total organic carbon than either alum or ferric chloride. And while it may be a bit more expensive than the ferric, the amount needed is roughly only 25-35% of the amount of ferric required, so it’s often the same price or cheaper for a gain in performance. 

Even if AQ-8921 or even AQ-8925 can be great replacement to ferric chloride, it always depends on the water chemistry and challenges. To help you determine which replacement product to try, Aquasan offers free jar testing.