Legionella Remediation – Installation of Secondary Disinfection System utilizing Chlorine Dioxide Technology

Metro recently completed the installation of a permanent Secondary Disinfection System (pictured below) utilizing Chlorine Dioxide for a building drinking water system that experienced the persistent presence of the Legionella Bacteria over an extended period of time.

Metro employs Chlorine Dioxide as a disinfectant for Legionella Remediation for its ability to penetrate biofilm and get to the source of the problem, something Chlorine and Bromine can’t do.  And as Chlorine Dioxide is generated onsite, no chemicals have to be mixed or stored, making it a much safer option.

Often times, a one-time Disinfection of a piping system is enough to remediate the presence of Bacteria, but in some instances with persistent issues, the permanent installation must be considered.

For more information, please get in touch and we will connect you with your local Metro Consultant.


For more information on Legionella and Industry Regulations and guidelines, click here.

Troubleshooting Water Softeners

Having problem with your water softener?  Metro can assist your facility in walking you thru a few simple troubleshooting steps.

The most common water softener problem is a poor brine draw.  Poor brine draw is typically caused either by a leaking brine draw tube, (flexible tube leading from brine tank to softener head) or a cracked or damaged brine check valve assembly. Item 2 on diagram

Brine tanks and valves should be cleaned out every year, as salt always contains some amount of foreign material, plugging valves and interfering with brine draw.

If indeed the softener is drawing brine well, then an elution study and/or a resin analysis may be necessary.

Brine Tank

Contact your local Metro representative for more details!

Customer blames fitness club’s negligence for his illness

by Noddy A. Fernandez |

Apr. 6, 2018, 1:04pm

ORLANDO — An Orlando customer is suing a fitness club, alleging it allowed Legionella bacteria to exist in the water fixtures of its premises.

Reinaldo Mariaca filed a complaint March 26, in Orange County Circuit Court against Fitness International, LLC, failure to exercise reasonable care in maintaining premises in a safe condition for the safety of clients.

According to the complaint, on May 26, 2017, Mariaca was lawfully upon the premises of defendant’s LA Fitness club in Orlando. Mariaca says he contracted legionella pneumonia after utilizing the showers, water fountains, spas, pools and water fixtures within the club.

As a result, Mariaca say he suffered has bodily injury, loss of the capacity for the enjoyment of life, and the expense of hospitalization, medical and nursing care and treatment.

The plaintiff alleges Fitness International failed to adequately inspect the showers, water fountains, spas, pools and water fixtures on the premises to determine whether the Legionella existed before guests utilized the premises.

Mariaca seeks trial by jury, damages in excess of $15,000, plus interest and court costs. He is represented by attorney Lawrence Gonzalez II of Morgan & Morgan PA in Orlando.


Source: https://flarecord.com/stories/511384266-customer-blames-fitness-club-s-negligence-for-his-illness

New Legionnaires’ Cases at Veterans Home

“QUINCY, IL (WGEM/CNN) – Two new cases of Legionnaires’ disease have been reported at a veterans home where more than a dozen people have died from the disease since 2015.

“I have no idea why it’s still happening, because I know they put a whole new water system in out here when the first outbreak came out in 2015,” said Bill Huber, whose father resides in the home. “It’s still frustrating that it’s still happening.”

The Illinois Department of Public Health said two residents showed signs of pneumonia on Feb. 8. That’s when tests were sent to a local hospital.

When those tests came back negative, different tests were done at a state lab. Those tests confirmed Legionnaires’ disease.

“Look, the capital development board should be brought in,” said Illinois state Sen. Tom Cullerton, D-Villa Park. “There’s 15 million dollars of federal funds that could be utilized, and the governor should come to us to appropriate whatever else is needed to get the problem fixed, but he’s not doing that.”

With Legionella bacteria known to grow in summer months, Cullerton said it’s concerning to see it pop up in the winter.

“If it’s coming up in the dead of cold when it’s not supposed to, how quickly once that thaw hits, is it really going to start affecting the entire institution?” Cullerton said.

State Sen. Jil Tracy, R-Quincy, said these new cases will speed up the process for lawmakers to come up with a plan.

“We’re looking at the option to retrofit new piping from the new water treatment facility there, so all of it is being discussed,” Tracy said.

Bill Huber’s father suffers from Alzheimer’s and has been at the home for nearly a year. Huber wishes the state could solve the situation, but he’s glad to see local staff working hard.

“They check it every hour of every day, so they’re doing everything they can to keep the residents safe,” Huber said.

The Illinois Department of Public Health said engineers are scouring the home, looking for the presence of more Legionella bacteria. They also have put measures in place to protect residents and staff.”


Sources: http://www.mysuncoast.com/news/national/new-legionnaires-cases-at-veterans-home/article_f37f514e-9fd6-5630-b9c5-8f45a2d05236.html


All Legionella Test Results are Not the Same

Legionella testing laboratories will usually express their findings across all Legionella species using available culture methodologies (through ISO or CDC).  In some cases, laboratories are required by regulations to do so.  While on the surface, testing for all species of Legionella would seem to be more protective of public health, evolving information has shown the opposite.  This bears out in the literature to be the statistically and internationally accepted logic.  In September 2017 the World Health Organization released its recommendation that water systems be monitored for Legionella pneumophila specifically.  Their report was confirmation that Pneumophila is clearly recognized as the causative agent of legionellosis, and not the other Legionella species.  Identification of non-pneumophila species could lead directly to unnecessary response and expense.  The door could be opening for the acceptance of more focused testing methods, where specific isolation of Pneumophila promotes better problem ID, testing accuracy, and mostly reduces the cost of administering a water management plan.

Written by: John D. Caloritis, CWT, Technology Director

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Softener Equipment

Sodium zeolite softener systems consist of a softener tank, valving and a means of transporting brine (salt solution) to the softener tank.  The tank includes a service and rinse water inlet distributor, freeboard or the headspace from the top of the resin bed to the top of the vertical wall of the tank, a regenerant distributor, a bed of ion exchange resin and sometimes a supporting medium or outlet distribution system.

The inlet assembly is designed to evenly distribute the incoming water.  It also acts as a collector for the backwash water that goes to the sewer.

The feedboard space allows the resin to expand without loss to drain during the backwashing.  It should be designed to permit a minimum of 50% expansion.

The regenerant distributor located above the resin bed, spreads the brine uniformly over the resin beads.

A bed of resin, operating in the sodium cycle, softens the water.  The quantity of resin used depends on the raw water hardness, the quantity of water to be treated per regeneration, flowrate, and the regenerant level employed.

An underdrain system evenly collects the treated water, waste brine and rinse water, and distributes the backwash water.

It is not unusual to have a valving system that consists of either a valve nest or a single, multiport control valve.  A nest of six (6) main valves is needed for the service inlet and outlet, backwash inlet and outlet, brine inlet and rinse outlet.  The valves may be either manually operated or any variety of air-, water- or motor-operated automatic valves.  A single, multiport control valve may be used in place of the valve nest.  As the multiport valve moves through a series of four positions, the ports in the valve direct the flow of water in the same manner as the opening and closing of separate valves.

The brining system consists of a salt dissolving/brine – measuring tank.  It is used to prepare a saturated brine solution.  This tank frequently has a float – operated valve to control the fill and drawdown level and thus, the quantity of brine added to the softener.  Usually an eductor transfers the saturated brine to the softener and dilutes the saturated brine with inlet water to the desired concentration for resin regeneration.

A future article will include a guide to softener troubleshooting along with additional information on softener operation and maintenance.

Softener Operation and Regeneration

Softener Operation

A sodium zeolite softener operates through two basis cycles:  the service cycle, which produces soft water, and the regeneration cycle, which restores the exhausted resin to capacity.  During the service cycle, raw water enters the softener through the inlet distributor, flows through the resin bed, is collected by the underdrain system and then transferred to the point of use.

When a softener is exhausted, it must be regenerated.  A number of methods may be used to signal the need for regeneration.  Many facilities rely on operator testing to determine when hardness breaks through.  Another common method for determining when regeneration is needed is to measure the quantity of water treated between regenerations.  A water meter in the service water line is used to sound an alarm or automatically initiate regeneration when a preset number of gallons has been softened.

Softener Regeneration

As we have said, regeneration is the process by which the resin is exposed to a strong concentration of highly ionizable material, such as salt.  While the resin has a greater affinity for calcium and magnesium than for sodium, the high concentration of the regenerant forces the ions on the bead into solution and substitutes the sodium ion.  This process is called elution.  The concentration of the regenerant is a critical factor in all ion exchange.  Softener regeneration generally consists of four (4) steps:

  1. Backwash
  2. Brining
  3. Slow Rinse
  4. Fast Rinse


Backwashing is an upward flow of water which lifts and expands the resin bed.  It removes the accumulation of particulates (entering via raw water) and resin fines (broken pieces of resin).


The brine regenerant stream enters the softener, flows downward through the resin bed and then is discharged to waste.

Slow Rinse:

A low flow rate of rinse water follows the regenerant to displace the brine downward through the resin bed while slowly rinsing the unit.  The flow rate for this slow rinse step is the same as the flow rate for the brining step.

 Fast Rinse:

A high flow of rinse water follows the slow rinse procedure to remove residual brine from the resin bed.  The flow rate for the fast rinse step is identical to the flow rate while the softener is in the service cycle.

Usually a unit can return to service as soon as the hardness value reaches the desired preset level, but some operators continue to rinse until chlorides are reduced to a value near that of the influent level.

Again, the frequency at which any resin must be regenerated is a function of:

  1. The volume of water treated.
  2. The concentration of exchangeable ions in the water.
  3. The type of resin.
  4. The amount of resin present.
  5. The type of regenerant.
  6. The amount of regenerant.


Principles of Zeolite Softening

Principles of Zeolite Softening

Sodium zeolite softeners use exchange resins made of polystyrene.  These resins have sodium ions loosely attached and will readily give up sodium for more desirable ions such as calcium and magnesium.  This exchange is only for cations (positively charged ions).  This is why sodium zeolite resin is referred to as a cation exchange resin (Figure 2).


Figure 2 – Sodium zeolite resin gives up sodium ions for calcium and magnesium

The water to be softened passes through the vessel containing resin.  Calcium and magnesium ions are exchanged for the sodium ions in and on the resin beads.  The sodium then takes the place of the calcium and magnesium with the appropriate anion (negative component).

A plot of the softener effluent profile shows a low, nearly constant effluent hardness level until the ion exchange resin nears exhaustion.  At this point, the hardness level usually increases quite rapidly and regeneration is required (Figure 3).

Figure 3 – As the resin nears exhaustion, the hardness level increases rapidly.

Regeneration is achieved by reversing the softening reactions.  Exhausted resin is exposed to a concentrated solution of sodium chloride.

Normally, zeolite resin more readily releases sodium in exchange for calcium and magnesium.  However, with the high concentration of sodium in the brine, the sodium ions displace the calcium and magnesium ions attached to the beads.  Thus, the high concentration of salt in the regenerant supplies the driving force to replace the hardness cations.  The calcium and magnesium are removed from the softening unit through the wave brine and rinse streams.

The frequency of regeneration needed depends on the rate or quantity of water, the calcium and magnesium content of the raw water, the quantity of exchange resin in the softener and the amount of salt used per regeneration.  The operating plant usually controls only the flow and the amount of regenerant.  The other parameters are fixed by the system design and the raw water hardness level

Softener Application and Ion Exchange

Softener Application

The potential for scale and deposit buildup exists in every raw water supply.  The ability of the sodium zeolite softener to reduce this potential effectively and economically makes this an ideal pretreatment for boiler feedwater and many types of chemical process waters.  Compared to other softening methods, sodium zeolite units offer many advantages:

  1. The treated water has a very low scaling tendency because this method reduces the hardness level of most water supplies to less than one part per million (ppm).
  2. Operation is simple and reliable; automatic regeneration controls are available at a reasonable cost.
  3. Regeneration is accomplished with inexpensive, easy-to-handle salt (NaCl).
  4. Waste disposal usually presents no problem.
  5. Within limits, variations in the water flow rate have little effect on the treated water quality.
  6. Efficient operation can be obtained in almost any size unit, making sodium zeolite softeners suitable for both large and small installations.

The Ion Exchange Process

Ion exchange is the process in which materials exchange one ion for another, hold it temporarily, and release it to a regenerating solution.  These materials are widely used to treat raw water supplies which contain dissolved salts.  Today the most commonly used material is an ion exchange resin.  Resins are plastic beads to which a specific ion has been attached – an ion which is exchanged for other ions in the water supply (Figure 1).  Once the resin has given up or exchanged most of its exchangeable ions, it is said to be exhausted and needs to be regenerated by coming in contact with a strong solution of ions called the regenerate.  The regeneration procedure will be explained in detail later in this article.

Softener Operation and Troubleshooting

Good water softener operation is often a key factor in efficient boiler system performance.  In its simplest terms, softening is the removal of naturally occurring scale-forming ions that are present in all water irrespective of its source.  Although we take it for granted, the operation of a water softener is really a remarkable phenomenon.  As you can see in the example below – a properly functioning can, in fact, remove thousands of pounds of potentially costly calcium and magnesium (hardness) from boiler water.

The whole softening process is based on ion exchange – the means by which sodium ions in the softener resin are exchanged for calcium and magnesium ions.  The beauty of all this is that the process is reversible.  Once the softener resin has given up its sodium ions in exchange got hardness ions, the resin can be regenerated to begin its work all over again.

The ion exchange process has evolved from its discovery in England around 1850, through the development of natural and synthetic exchange materials called zeolites (a name that stuck), to today’s complex ion exchange resins consisting of hydrocarbon networks to which ionizable functional groups are attached.

Understanding the sophisticated physical chemistry of the ion exchange process is not our goal here.  Our real objective is a basic understanding of how the system is supposed to work and how a smoothly running softener can help overall boiler operation.