Do you need to remove or increase the hydrogen sulfide removal efficiency in your reverse osmosis system?
There are many forms of water treatment processes in the industrial water treatment market and most of us would agree that to maintain high water standards and water quality it requires the use of multiple types of treatment systems to achieve results. Let’s face it, we do not win or get a “that a boy” when we design and build the best reverse osmosis system and
when we turn the brand-new water system on and the water still smells like “rotten eggs”. Yes, that is an embarrassing moment!
The problem is we typically design around what we can see or read. When was the last time you reviewed a water sample and it provided details of how much dissolved gas was in the water? Most likely never. A typical water treatment system may deploy reverse osmosis as the primary treatment method and why true RO will remove particles that have size and weight (ions and molecules) typically defined as a certain size (micron) but RO does nothing to remove the dissolved gases that are already entrained within the water naturally or were created by adjusting the pH.
You see, the need to protect the RO membrane from fouling or scaling can create the dissolved gases in the water that give you that “rotten egg” smell or Hydrogen sulfide odor. So one treatment now creates the need for another!
It is important when beginning to design a degasification system for an industrial water application that you first have good water test data from a certified testing laboratory. Identifying the presence of hydrogen sulfide (H2S) in the early stages of the design as well as other harmful minerals that may cause scaling will enable you to predict whether or not the addition of a degasification tower is needed to remove the Hydrogen Sulfide dissolved gases. In addition this may provide the insight on whether or not you will need a chemical or biological scrubber for the off gases after the degasification or decarbonation process. Also, it would be nice to have a crystal ball that could predict how fast the RO membranes may foul or scale but I have never had the opportunity to see one but it is important to try to maximize and improve the CO2 efficiency removal because the extra effort may save your Ion exchange resin and will no doubt extend the life between regeneration cycle which will reduce O&M costs
I have learned from the old fashion “School of hard knocks".
Learning the key of course to designing a good industrial water treatment system is to first admit that none of us understand everything there is to know about water treatment. Let’s face it, how many times have we all had a “ah ha” moment on a job? Yes, it is good to have a strong background in water chemistry but the truth of the matter is most top notch water design professionals learned from the school of hard knocks and making mistakes and having to fix the mistakes later. Always take the time and obtain goo up front water analysis data and understand what the water has in it as well as the waters Langelier index (LSI). These and other variables will allow a design professional or a design manufacture to properly size and select the maximum efficiency treatment process and select what additional pieces are required like a Decarbonation or Degasification tower to be added into the process to remove dissolved gases such as Hydrogen Sulfide and Carbon Dioxide. And remember, there is a direct relation to removal efficiency and pH and temperature when you are designing a water process system. If the pH of the water to be treated is at a 7.0 or higher it is unlikely you will achieve removal efficiencies above 90% in a degasification tower intended to remove Hydrogen Sulfide. However, as the inlet water pH moves more acidic to a perfect 5.5 pH you can achieve a removal efficiency of 99.999%. Last, don’t forget now that you have maximized the removal of Hydrogen sulfide gases from your reverse osmosis process the degasification tower should also serve as a “decarbonator” to remove carbon dioxide and to naturally raise the pH without the use of chemicals. So maximizing the design and selection of the distribution system should be key to ensure high removal and hydraulic load distribution across the media bed of the tower. At DeLoach industries, inc. we maximize removal efficiency of en-trained gases right from the point of entry into our towers. For more information on your water treatment needs, contact the professionals at DeLoach Industries, Inc at (941) 371-4995.