The SOLVOCARB process from Linde North America is a fast and economical way for process industries to neutralize alkaline wastewater with a high degree of control using carbon dioxide (CO₂). The SOLVOCARB process injects the inert gas into the process wastewater, and includes Linde CO₂ gas supply and metering system. When dissolved in water, CO₂ forms carbonic acid to quickly reduce pH to appropriate levels for discharge. The process is also useful for reverse osmosis (RO) and remineralization systems. 

Carbon dioxide is an inert gas and mild buffering agent, so SOLVOCARB provides a much safer alternative to hazardous and corrosive mineral acid treatments, such as sulfuric acid (H2SO₄). With mineral acids, a few drops too many can create pH excursions which risk discharge fines from the water treatment authority or U.S. Environmental Protection Agency (EPA).

With SOLVOCARB, gaseous CO₂ can be injected into waste water using a variety of methods:

• SOLVOCARB-B for open treatment tanks and pools via diffusion mats.
• SOLVOCARB-D for direct injection into wastewater pipes via a sparger.
• SOLVOCARB-R for injection into enclosed process tanks via special reactors.

Process-Water Rescue Treatment
A major pet food manufacturer called on the Linde Water Treatment team after a failure in an acid dosing system overshot the set point, dropping the pH down to 3, and caused a regulatory problem. With help from Linde, the problem was corrected with the controlled addition of CO₂ using the SOLVOCARB-D method.  Linde installed the gas sparger inside a 2 in. waste pipe to treat the process water, in line, as it flowed.

“Small gas bubbles increase mass transfer, so CO₂ is quickly absorbed by the water, creating carbonic acid which neutralizes the alkalinity,” explains Applications Sales Engineer Stefanie Gregg.  The gas was supplied on-site via a 30-ton vertical vacuum-jacketed tank. 

Linde also offers oxygen (O₂) and ozone (O₃) gas-dissolution systems for water treatment.  The Linde Water Treatment Team reviews treatment challenges and develops complete engineering solutions for the storage, metering and injection of gases.  

For more information, visit Linde at www.lindewatertreatment.com, or call 800-755-9277.