DELOACH BLOG

Select the best type of odor control, fume, or air emission scrubber.

Industrial and municipal operations often face the challenges of capturing and treating air emissions from their process operations.  Off-gases, fumes, and odor emissions can be generated from the downstream process or material handling, such as those in the municipal wastewater industry.  However, industrial operations often generate fumes and off-gas air emissions from either the production of chemicals or the use and application of chemicals like acids and a wide range of other chemicals. These types of air emissions share a common need to be safely captured, contained, and treated to make the air steam safe before its release.  Some types of air streams create an odor that becomes a nuisance, as is typical with municipal waste that often releases Hydrogen Sulfide (H2S) and or Mercaptans (R-SH) gas during decomposition.  

Many variables should be considered

when beginning to choose the best type of air emission treatment process.  Within the industry, there are wet chemical scrubbers, dry absorbent scrubbers, biological scrubbers, and destructive type scrubbers such as catalytic and thermal oxidizers and flare technology that utilize heat to destroy and consume and oxidize certain types of off-gases. 

Each type of air emission process has its own parameters where it will perform optimally, and each type of scrubber has different levels of operating challenges and associated operating costs.  So how does one select the best process for each application?

At DeLoach Industries, we like to help customers with this evaluation process by completing a checklist guide, which helps guide the customer to the most economical and safe solution. Going through this process can help eliminate costly mistakes that may otherwise be overlooked.  Solutions are often selected by looking at the contamination only or by familiarity with the process.

Hydrogen sulfide (H2S) contamination in water is a very common issue. A distinctive smell, combined with a dark precipitate that leaves behind damaging deposits, is an indication that there is H2S in your water. From the irritating smell, corroded plumbing & staining, to far more dangerous health concerns, contaminated water can cause serious issues in industrial and municipal environments.

When looking for the best method to remove the gas from your  water treatment system, you want equipment that is highly efficient and cost-effective. You also want the method to be safe and require minimum capital to initiate. Of all the available methods, few are as efficient, cost-effective, and easy to implement as degasification.

Degasification

Generally speaking, degasification is the elimination of dissolved gases from water using various means. In this case, we are looking at the use of a membrane to filter off Hydrogen Sulfide from drinking water to render it clean and safe for use. In membrane degasification, a proprietary membrane cartridge is used to remove the gas from the water. With vacuum conditions on one side of the membrane and the contaminated water on the other side, the dissolved gas (H2S) is moved by the vacuum to the other side of the membrane, leaving the water molecules unable to move across. This happens very quickly and the method is highly effective. The resulting water is void of any contamination, and safe for drinking and commercial use. 

What is the difference between Aeration, Decarbonation, or Degasification, and which one is right for your water process application?

To answer this question, we first need to have a clear understanding of what benefits each of these (3) three different types of treatment processes for your water application.

• 1. The term Aeration means, to induce or maintain the oxygen saturation level in water in a natural state or an artificial one.  When utilizing an Aerator you can expect to induce additional oxygen into the water stream that is passing through the system to the maximum saturation level possible at the current water temperature.  As saturation levels will vary with water temperature it is important to always take the inlet water temperature into consideration. If your goal and objective are to remove iron as an example from the water process an Aerator unit should be considered and utilized as one of the most cost-effective methods of inducing oxygen and initiating the oxidation of iron. Converting Ferrous to Ferric iron then can be settled, collated, and filtered.  Aerators manufactured by DeLoach Industries are NSF-61 certified and fiberglass compliant to RTP-1 standards and are available in a wide variety of sizes and materials. For heavy iron, magnesium, or calcium application the systems are available in a square design allowing for self-cleaning PVC slat trays to be utilized in place of loose fill media which will foul more frequently.  Aerators are also available in a round tower design for non-iron applications to accommodate loose-fill media packing and are either a Forced or Induced draft configuration to accommodate applications where Hydrogen Sulfide may be present within the feed water to prevent corrosion from attacking the blower. The equipment can be manufactured from Fiberglass, Aluminum (depending on other contaminants), Stainless Steel, or rubber-lined steel and are available to accommodate flows from 5 to 4,500 GPM (gallons per minute).
  
  
• 2. The process of Decarbonation refers to the removal of Carbon Dioxide (CO₂) from water. CO₂ can be naturally found in a water process or can be created from other elements such as Carbonic Acid which in the presence of water converts to free CO₂. There are several reasons for removing CO₂ from a water process which includes pH control, corrosion prevention, and reduction of operating costs when utilizing ion exchange for water softening. A Decarbonator is a piece of equipment that is manufactured specifically to remove CO₂ from the water, and it is then exhausted through the vent located at the top of the unit.  DeLoach Industries manufactures’ Fiberglass RTP-1 and NSF-61-compliant Decarbonators for water applications within the Municipal, Industrial, Food and Beverage, and Aquaculture markets. It is very common to utilize a Decarbonator post-membrane filtration, or prior to Anion and Cation treatment.

CO2 & pH In municipal and industrial water processes

Carbon Dioxide (CO2) in municipal and Industrial water can create problems in the water treatment process, increase operational costs of the treatment plant, and cause excessive corrosion to equipment and ancillary equipment.

In nature, one of the most natural common causes that create low pH or acidity in water is an element known as “Carbon Dioxide” (CO₂).  The process of how carbon dioxide enters the water in the first place is a topic worth exploring.  Nature creates one of the most common causes of CO₂ found in the water naturally. When the water reaches an equilibrium with our atmosphere followed by the biological degradation that is aided by the photosynthesis of organic carbon (CH₂O) then carbon dioxide begins to form. Organic carbon is dissolved in water and it forms “Carbonic Acid”

(H₂CO₃).  CO_{2 (g)} + H₂O _(l) = H₂CO_3 (aq). 

The process to form the carbonic acid is slow and only a small portion remains as an acid because proton losses occur during the process.

H₂CO₃ (aq) « H⁺ (aq) + HCO₃^- (aq)

CO₃^- (aq) « H⁺ (aq) + CO₃^2- (aq)

Municipalities and their Engineers often wonder why they should design and invest in a degasification system for their water treatment facility. This system removes unwanted gases from the water, which can improve the water quality and safety. Investing in such a system can therefore be beneficial. What are the problems and cost advantages that degasification will help you overcome?

Degasification is the most cost-effective means of providing higher-quality water and lowering your operational cost. Proper degasification reduces chemical consumption and TSS in treated water. It also prevents corrosive conditions, sulfur, and sulfur bacteria from forming in downstream conveyance and distribution systems.

This extends the life of your equipment. Here are 4 ways that a degasification system can solve your water problems:

1. Produce Higher Quality Water

Degasification eliminates the need for extra chlorine or caustic to be added to the final product water. It is used to remove H2S or reduce CO2 levels. We can reduce the need for chemicals by stripping the Hydrogen Sulfide (H2S) from the water with degasification. This results in lower Total Suspended Solids (TSS) levels and better taste for the consumer.