The need for pH control with water degasification and decarbonation in water treatment includes almost every industry and includes;
The need for pH control with water degasification and decarbonation in water treatment includes almost every industry and includes; Aquaculture, food and beverage, industrial, municipal, and even pisciculture. In some water treatment applications, harmful gases such as Hydrogen Sulfide (H2S) are removed, while in other applications, Carbon Dioxide (CO2) or a combination of both. In addition, there's a host of other organic and inorganic elements found in water, both naturally occurring and manmade, that require removal during some part of the water treatment process.
In almost every application of degasification or decarbonation, you will hear or see the term pH used either by need or by the result. If, as an example, the water treatment application requires the removal of Hydrogen Sulfide (H2S) to be removed either as “free” gas or requires the conversion of Sulfides into (H2S) gas. You will often also see the need to adjust the pH of the water chemistry to maximize both the removal and the conversion to increase the efficiency of the equipment being utilized to remove the hydrogen sulfide, such as a degasification tower or commonly called a degasifier.
So, what is pH?
Water pH is a term used to describe whether or not the water is “acidic” or “basic.” pH ranges in water can be from 0-14. 0 is the most acidic, and 14 is at the far end and is the most basic, leaving “7” as the neutral state. A pH of 7 is neither acidic nor basic. So, what causes pH to be acidic? In nature, the most common cause of a low acidic pH in water is Carbon Dioxide (CO2) which occurs naturally when photosynthesis, decomposition, or respiration occurs in nature. The increase in CO2 causes an increase in ions, producing a lower pH in a simplified explanation.
How does pH play such a significant role in degasification and decarbonation?
As mentioned above in the example of the removal of certain harmful elements such as sulfides, sulfates, and free H2S hydrogen sulfide gases, to maximize the removal from water utilizing a degasification tower, it is essential to maintain as close to a pH of 5 as possible. When the pH rises above 5, the ability to convert and strip the free H2S gas from the water diminishes. When a degasification tower operates within this specific range and if it has been designed with the higher efficient distribution systems such as the ones utilized by DeLoach Industries, removal efficiencies of 99.999%- 100% can be achieved. If the pH rises to seven or above, the removal process becomes much more complex, and typically, you will have much lower results. The pH adjustment during the water treatment process is typically accomplished by adding commercially available acid, such as “sulphuric acid,” one of the most common in the municipal and food and beverage industry.
What happens to the pH in water when you remove Carbon Dioxide (CO2)?
If you are treating water that either already has a lot of free CO2 naturally or if the water pH has been previously adjusted lower either to remove H2S or prevent scaling within a membrane treatment of filtration treatment, then most likely you already have carbonic acid and free CO2 present within the water. So, when utilizing a degasification or decarbonation tower system by DeLoach Industries, as the gases are removed, you will see the pH of the water rise. Typically, if the pH is 5, then after decarbonation, the pH will have risen to 6 or as much as 6.5. Removing the free CO2 increases the alkalinity and becomes more basic (neutral). In some cases, when there are different types of acids used or the pH is taken down too low, or all of the organics have been removed when the pH rise may be minimalized during the process. This is why understanding water chemistry and the specific application and need are essential.