In municipal and industrial settings, the most common cause of acidity in water is aqueous carbon dioxide. High enough concentrations of CO2 can lower the pH levels of water to a point that corrodes pipes and machinery or harms fish grown in aquaculture.
In cases where high levels of CO2 is present in water, a carbon dioxide stripping system will keep pipes intact and fish healthy. CO2 degassing systems strip the CO2 from the water, making it possible to balance the water’s pH level.
CO2 degasifiers, or carbon dioxide strippers, are one of the most cost-effective ways to remove CO2 from water.
How Does Carbon Dioxide Stripping Work?
Carbon dioxide in water is classified as a weak acid, meaning that it will partially dissociate. When CO2 dissolves in water, some of it will react to form carbonic acid. Then, some of the carbonic acid molecules will then break down, forming bicarbonate and pH-lowering hydrogen ions.
CO2 degasifiers work on the same principles as air strippers. In the process of degasification, also referred to as decarbonization, water flows downward through the CO2 degassing tower while an airstream flows upward.
Many CO2 degassing towers designs feature tower packing. Tower packing is media, often hollow and spherical, that is added to towers to increase the contact surface area between water and the gas being stripped. MACH Engineering recommends Tri-Packs for this application.
One important phenomenon to consider in degasifier design is “free” versus “fixed” CO2. In decarbonization applications, as the pH of the system rises, some of what was free CO2 shifts towards fixed CO2. As a result, the CO2 transfer to air becomes slower in the lower part of the packed tower. To adjust for this, greater packed height is needed for the same CO2 removal. The higher the pH, the greater the packed height needed.
Applications of CO2 Degassing Systems
CO2 is sometimes used to reduce the high pH level in water treatment systems. On the other hand, an excess of CO2 can make the water overly acidic, leading to the corrosion of pipes and solder. Alkaline substances such as lime can raise the water’s pH, but only after a CO2 degasifier removes the carbon dioxide from the water. This is primarily because water with a pH above seven tends to retain CO2, and can continue to acidify even after an alkaline substance is added.
Corrosion of old pipes — especially lead pipe — presents a massive health risk. The U.S. Environmental Protection Agency’s (EPA) Lead and Copper Rule, regulates how much lead and copper drinking water can contain before you must implement a water system. Water treatment plants often use CO2 degassing when lead levels in a system rise above acceptable levels. Elevated lead levels aren’t a guaranteed sign that the water’s pH is too high, but it does indicate that the local water might be too acidic.
Other industries that use CO2 degassing systems include shellfish farming and aquaculture. In these industries, you need to carefully maintain water pH. If not, it can harm the health of the farmed fish.
Customized Scrubbing Solutions
If you need a full-service scrubbing solution, we can work with you. At MACH Engineering, everything starts with the client. Each step of the process — from design to installation — is customizable to fit your needs. If you need scrubbing solutions, from packing components to whole scrubber systems, contact us today.