DELOACH BLOG

A Biological Odor Control Scrubber Is Just One Of Many Different Types Of Available Technologies to treat air emissions that may contain harmful gases.

This class of equipment commonly falls into a category referred to as “Odor Control Scrubbers” and they are utilized to remove dangerous or noxious odors from an air stream. The Biological Odor Control System has gained popularity among many end users such as municipal operators due to the reduced operating cost and more simplistic operating requirements. A typical chemical odor control scrubber often requires two or more chemical additives and more instrumentation is required to maintain system performance. With the additional chemicals required and instrumentation comes the need for more hands-on maintenance, calibration, and safety requirements which increases the operating costs and workload of the operator.

A Biological Odor Control System relies on active bacteria cultures that recirculate within a water stream and flow across a random packed media bed that is beneficial to the bacteria culture.

During the process of metabolizing harmful gases such as Hydrogen Sulfide (H₂S) the biological odor control system requires only the addition of Caustic to control and balance the pH and additional water makeup to replace what has been consumed through evaporation or during the blowdown process to eliminate solids. There are several different types of odor control and chemical wet scrubbers, industrial air scrubbers on the market today and each provides a solution for the treatment of noxious or corrosive gases and odors in the industry.  And even though Biological scrubbers are commonly utilized in municipal applications for the treatment of hydrogen sulfide (H2S) gases that were produced by a water or wastewater treatment process there are times when a Biological Scrubber does not provide the best solution for treatment. When there are wide or rapidly changing concentrations in the ppm (parts per million) level then a Biological Scrubber will have difficulties balancing and acclimating fast enough to prevent a breakthrough.  As an example, In water treatment, there is a treatment process referred to as “degasification” which strips the hydrogen sulfide gas from the water, and then the concentrated H2S gas is exhausted from the tower through an exhaust port.  When the concentration rises above 1 ppm for hydrogen sulfide gas then the levels become both noxious to the surroundings as well as corrosive. Many times, the levels range from 3-7 PPM in concentration with Hydrogen Sulfide and pose a serious health threat, noxious odor, and corrosive environment demanding capture and treatment. When utilizing an Odor Control Scrubber such as a Biological Scrubber the gases are pulled or pushed through an air duct system that is connected to the Biological Scrubber inlet or suction side of the blower. The same process is utilized when treating Hydrogen Sulfide (H₂S) gases that were captured at a wastewater treatment process. These gases may have been generated from a source such as the wastewater treatment plant, lift station, or master head-works facility. When captured the gases are also conveyed in a similar manner to the Biological Odor Control Tower for treatment.

The type of Odor Control Wet Scrubber selected for the treatment and neutralization of Ammonia (NH3) gases depends on several variables, including the type and source of the ammonia gas and whether or not it is “Free” ammonia and or unionized.

Ammonia is a very miscible and stable molecule with solid hydrogen bonds, making it very soluble in water and difficult to treat without using a properly designed and sized ammonia scrubber. The concentrations, air flow rates, temperature of the gas stream, and chemical reagents being utilized, such as caustic to remove and then treat the ammonia, all play a significant role in the removal efficiency of the ammonia gas scrubber system. Unlike other types of “odor control scrubbers,” an ammonia scrubber is much more sensitive to variables such as the gas stream temperature because of the solubility of ammonia.

the process is called the Haber Process by combining nitrogen with air and adding pressure, you can make ammonia.

It takes about 200 atmospheres of pressure, and the process varies from refinery to refinery. Still, on average, you can only make approximately 15% of ammonia during each pass which takes multiple passes to achieve the 15%. The reaction to make ammonia is exothermic when produced in a refining process. 

However, ammonia is also formed in nature in smaller quantities. Most ammonia (90%) is utilized for fertilizer production, but ammonia can be found in food, pharmaceutical products, and cleaning supplies. When ammonia gas is released into the air, it has a very noxious and pungent odor that can be dangerous to inhale, so often, odor control scrubbers are required to capture and treat the ammonia gas.

Ammonia (AM) is a common water pollutant that significantly impacts the water process industry.

It is not just polluting water bodies but also aqua wells and humidifiers. Generally, AM is produced from human sweat and urine and created from synthetic ammonia in industrial processes.

Ammonia has three types of amines – primary, secondary, and tertiary – all are toxic for humans and aquatic life.

• Primary Amine has two carbon and one nitrogen atom, also called methylamine or CHNH2.
• Secondary Amine has two nitrogen atoms with no carbon atom between them, also called Dimethylamine or CH2(NH)CH3.
• Tertiary Amine has three nitrogen atoms with no carbon atoms between them; thus, it’s called Trimethylamine or CH3C(NH)CH3.

In natural conditions, primary Amide bacteria produce Amide under high-temperature conditions. In an aqueous solution and soil environments with high pH levels (>6).

Primary amide can form by the dehydrogenation of nitriles, such as acetonitrile, which are further oxidized to form acetic acid. 

Primary amide form by alkaline hydrolysis of nitro compounds such as 2-nitrophenol.

Process systems often need to recognize when the Degasification or Decarbonation system is failing or underperforming.

Water treatment towers and storage tanks are high places that require special precautions when entering. While the majority of people who enter these locations for work can be trusted, there are some hazards that make it more important than usual to follow safety procedures.

These locations can get very hot and humid, and can also be filled with harmful chemicals and microorganisms that can cause serious health issues if inhaled or absorbed through the skin. Therefore, the general standard for workplace safety is much higher when entering locations like these.

Make sure you have read and understood the following information about safety when entering a water treatment plant. It will help you understand how to stay safe and protect yourself from harm when entering a water treatment plant. normal installation, maintenance, or even emergency repairs, it is often required to enter into a water treatment tower (degasifier, air stripper, decarbonator, or clear well/ storage tank). When this occurs, full safety protocols should be followed at all times, in accordance with OSHA regulations.  A tower or tank B classification is a "Confined Space" location. For more information visit the OSHA combined space regulations page.

In addition, there are other safety risks that an operator or technician can be exposed to while inside these types of closed locations. The risk can come from fumes of hydrogen sulfide (H2S), chlorine from an injection line, or a lack of oxygen O2. A proper confined space permit should be prepared and only technicians with proper training and certifications should enter into these types of confined spaces.