Converting Ferrous (Fe+2) (soluble) iron to Ferric (Fe+3) (Particulate/Solid form).

The iron must first be exposed to air or another form of an oxidizing agent. Aeration is the most cost-effective method to oxidize ferrous iron for its removal from water. In many areas around the globe, municipal and industrial operations have the need to remove naturally occurring iron (Fe) from the water to both prevent damage to other equipment as well as to improve water quality. To remove iron from the water it first must be oxidized using the most widely accepted and cost-effective method called aeration. The aeration process changes the iron from its Ferrous (Fe+2) state (soluble) to ferric (Fe+3) colloidal participation. Did you know that Iron occurs naturally and is found in the earth’s crust? It occurs in both groundwater as well as surface waters and is not known to cause any harmful effects on humans or animals.

Iron does cause problems though for municipal facilities and their customers by impacting laundry operations, causing stains on buildings, on plumbing fixtures. Iron also promotes and facilitates the growth of iron bacteria in water which creates a problem for distribution lines and piping systems. Once the lines become blocked this impacts the ability to distribute water to the customer. The presence of iron bacteria also becomes detectible even at low concentrations and impacts the taste of the water. The U.S Public Health Service Drinking Water Standard set a recommended maximum level of 0.3 mg/L in public water supplies.

The basics of water decarbonation

and the removal of carbon dioxide (CO2). The need to remove (CO2) is essential in most Aquaculture, Municipal, Industrial, and Food & Beverage Processes To understand you must familiarize yourself with Henry’s Law.

Henry's Law defines the method and proportional relationship between the amount of a gas in a solution in relation to the gas's partial pressure in the atmosphere. Often you will see and hear various terms like degasification, decarbonation, aeration, and even air stripping when discussing the removal of dissolved gases and other convertible elements from water. Understanding the impacts that Carbon Dioxide (CO2) can have on both equipment and aquatic life provides the basic reasons why the need to decarbonate water, exists. Carbon Dioxide (CO2) can exist naturally in the raw water supply or be the result of ph control and balance. In either case, the process called Decarbonation or Degasification provides the most cost-effective and efficient manner to reduce or tally remove (CO2) from the water. In addition to Carbon Dioxide (CO2), water can contain a variety of other contaminants that may impact the removal efficiency of the Carbon Dioxide. A variety of elements as well as dissolved gases such as oxygen, nitrogen, and carbon dioxide (CO2). A full analytical review of the water chemistry is required to properly design and size the “Water Treatment” process.

Breaking the bonds in water releases a dissolved gas

such as carbon dioxide (CO2) you must change the conditions of the vapor pressure surrounding the gas and allow the gas to be removed.  There are many variables to consider when designing or calculating the “means and methods” of the removal of carbon dioxide (CO2). When I refer to the means and methods. I am referring to the design of a decarbonator and its components. The means equals the size and type (Hydraulic load) of the decarbonator and the “method” equals the additional variables such as the cubic foot of airflow (CFM) and “Ratio” of the air to water to accomplish the proportional condition needed to remove the carbon dioxide (CO2).

The Term Sour Gas

refers to any natural gas or other gas that contains high levels of hydrogen sulfide (H2S). The H2S is typically naturally occurring and found in deposits of natural gas and when there are concentrations above 5.7 milligrams per cubic meter or 4 milligrams per cubic meter when tested under standard temperature and pressure. At these levels the industry classifies the gas as “Sour.” Of course there are variations to this classification dependent upon agency an organization.

A Sour gas is not to be confused with an acidic gas 

although one could be both a sour gas is strictly defined by having large quantities of hydrogen sulfide and is usually accompanied by having mercaptans which adds to the foul smell and odor. The term is often used in the oil refinery business and when gases contain sour gas the process to remove the hydrogen sulfide and mercaptans is referred to as “Sweetening”. The most common method to “sweeten” and remove the sour gas is by processing the gas through an “amine process” which removes the harmful gas.

When do you know if your decarbonation system needs service?

When a degasification tower or decarbonator become fouled there are several indicators that identify you may have a problem or its time to clean your system.  If the efficiency of the degasifier has dropped you will see an increase consumption rate of chemicals.  If you are removing less H2S in the degasifier your chlorine consumption will increase.  When you increase the amount of chemical reaction occurring in the water, you will see an increase in the TSS levels and drop in water quality.  As the H2S reacts with chlorine more solids will form and be present in the water and the water quality will diminish.

Another indicator of a fouling condition is the adjustment of pH in the Industrial Water Treatment industry you are required to meet the set standards. As performance of the tower drops the removal of CO2 will also drop leaving a higher pH level than may be desired. A quick inspection to check out the media bed should be performed. Also, do not forget to inspect the distribution system at the top of your tower and remember that all distribution systems are not alike and to inspect the condition of each of them may require additional efforts on your part. With a header lateral system you need to inspect the distribution nozzles but with a Weir or Tray type you will need to check the amount of scale or fouling that is building up on the Weir edge or int the bottom of the pan. If the Weir edge becomes fouled unevenly it will create "Channeling" of the water and an increase in the initial hydraulic load to a concentrated point on the media bed.

Do you think all distribution systems are made equal? 

Well if you do you may be surprised that there are a lot of variation in manufacturing protocols in aerators, degasifiers and decarbonators.  Aerators are often found in use at Industrial Water Treatment and municipal water treatment facilities around the globe. 

For water treatment you may be surprised to learn that one of the key items that separate different types of aerators and decarbonators  for water treatment is the type of distribution system it utilizes.  To improve Carbon Dioxide (CO2) or Hydrogen Sulfide (H2S) removal you need to select the best distribution system for the tower and make sure its maintained. Now, there are many types of aerators in general and the term is used broadly. From floating pond aerators, to waste water aerators, to vertical tower aerators, decarbonators and degasifiers for industrial water treatment aerators.  We will focus on the vertical tower aerators for industrial water treatment.  All types of Aerators and even degasifiers and even decarbonators and Odor Control Scrubbers require some type of distribution system to begin the process of gas transfer and to remove Hydrogen Sulfide (H2S) from water or Carbon Dioxide (CO2).  It is important to evenly distribute the water or chemical solution across the media bed. 

There are several types of distribution systems available and the three most common ones you will see on the market place are the “Tray” type, Weir, or the header lateral utilizing gas release “Nozzles”.   

The selection of what type of distribution system is typically driven from the marketing side of who is selling you the tower.  But in terms of real performance a distribution system utilizing a nozzle system will outperform a tray type distributor.  All packed towers are design utilizing the Henry’s Law Constant” theory of chemistry and what all towers rely upon is some type of method to break the surface tension of the water and expose the molecules of gases so that they either can escape or can be introduced to a reaction agent.

When towers are designed it is important to properly hydraulically load the top of the media bed.  This is Considered " Degasification Basics". This is important for many reasons and we will address these points in future updates.  When using a properly designed nozzle distribution system such as a DeLoach Industries header lateral system then you get the benefit of both proper hydraulic load across the bed but you also gain anywhere from 4-10% of removal efficiency depending upon the application.  When looking at a chemical scrubber verses a biological scrubber you will notice they too have very different distribution systems. DeLoach Industries, Inc. has learned over their 60 years in business how to maximize gas transfer release.  If designed and built properly the gas release process or interaction process (if designing a scrubber) has already began “before” it enters the media bed. 

DeLoach Industries Inc. has been serving the municipal, industrial, and food and beverage industries since 1959.

DeLoach Industries specializes in the design, manufacturing, operations & maintenance of water treatment, wastewater treatment, odor control, and pisciculture/aqua farming systems.

What makes DeLoach Industries Inc. unique is that, as an original equipment manufacturer, we have extensive knowledge and we understand how to engineer, design and manufacture the equipment you need. We are different from traditional fabrication shops in that they will typically build something specific to your drawing but if there is a problem they may not understand the process involved or even how to correct the problem.

We serve each customer on a project by project basis to fully understand your needs. We offer full in house engineering and CAD design support services, manufacturing services including operation & maintenance support, and field services including annual service contracts on all DeLoach and other brand water treatment equipment.

Fiberglass manufacturing methods at DeLoach Industries, Inc.

In this video, we talk about the fiberglass hand lay-up contact molding process for creating a small component that goes on one of DeLoach Industries' induced draft aerators.

For more information or to learn more contact the professionals at DeLoach Industries Inc. at (941) 371-4995.

Receive Your Free Odor Control E-Book

Related Blog: Why Aeration is the Most Cost-Effective Way to Oxidize Iron 

The first step is understanding the chemical analysis of the water you will treat.

Suppose this is an aeration process for iron (Fe) removal. In that case, it is vital to understand the water's concentration, pH, and alkalinity and the amount of calcium carbonate or other minerals present. Once you've determined that the water is suitable for the desired treatment process, you must choose equipment based on the water's volume and flow rate. Remember that water treatment equipment is not one-size-fits-all and is vitally important when selecting equipment to consider your water conditions.

If a tower's internals is damaged due to the weight of random pack media or fouled water and airflow, the pack media will become completely clogged, and water flow will be blocked. This will result in an expensive shutdown and repair. It is advised that routine service cleanings are carried out under a service contract.

For heavy fouling conditions, a slat tray media selection can save you both downtime and costs. Slat trays provide an anti-fouling benefit based upon the design intended to “shed” particulate as it is formed. They still need to be cleaned in heavy conditions, but far less often, and cleaning is more manageable. The tower process application requires high removal efficiency, then loose fill media may be the only choice unless a pretreatment tower with slat trays is installed in front of the process. Each application must be evaluated on its merits and reviewed for potential fouling and anticipated operating cost.

If fouled completely, loose fill, random pack media will block water flow and air and can, in some circumstances, become so heavy that the weight can damage the internals of a tower. This will cause a shutdown and more expenses to remove and repair. Routine service cleanings under a service contract are highly recommended.