What is Legionnaire’s Disease

It is a bacterial infection that is characterized by pneumonia. According to the Center for Disease Control (CDC), legionnaire’s disease is caused by bacteria known as Legionella pneumophila. There are at least 43 species of legionella however, it is the Legionella pneumophila strain that causes over 90% of legionnaire disease deaths.

In the United States, it is estimated that as many as 18,000 cases occur each year. Death results in 5 – 15% of the cases.

Legionella are commonly found in low concentrations in both natural and unnatural (man-made) aquatic environments. Within unnatural environments, where water is used in an evaporative heat exchange process, warm temperatures combined with poorly treated cooling water can create an environment ideal for proliferation of this deadly bacteria.

Because cooling towers, evaporative condensers and chillers are highly efficient at drawing large volumes of air to support the evaporative cooling process, airborne organic material such as leaves, insects, pollen, birds, cotton wood and other debris is usually drawn into the water system and if not maintained can accumulate, decompose and contribute to system fouling and microbial growth including legionella pneumophila.

Ideal conditions for legionella proliferation include water temperatures between 77 – 108 degrees Fahrenheit (25 – 42 degrees Centigrade), presence of organic debris, sediment, scale, stagnant conditions and presence of amoebae. Legionella naturally preys on amoebae and incidentally prey on phagocytic cells (part of human immune system) when inhaled thus leading to Legionnaire’s Disease. The legionella bacteria is transmitted by aerosol (mist) from devices such as cooling towers showers and faucets and aspiration of contaminated water. Person-to-Person transmission does not occur.

Controlling Legionella in Cooling Towers & Evaporative Cooling Systems.

Based upon a six-year committee effort, ASHRAE board of directors approved guidelines (known as guideline 12) that provides environmental and operational guidelines for maintaining safe evaporative water cooling systems. The guidelines are intended for use by: commercial cooling system designers, maintenance engineers, equipment manufactures, owners, operators and users.

Key Maintenance Recommendations (Guideline 12)

* Keep system clean using a microbial treatment program.
* Use a qualified water treatment consultant to establish and oversee a water treatment program.
* Keep system free of debris that can contribute to the food source for legionella. (Air Intake Filters can help to control debris and organic material build-up).
* Inspect and clean cooling equipment if it is found to have a build-up of dirt, organic matter or other debris.
* Inspect drift eliminators and clean or replace as needed.
* Keep maintenance and operational records that include equipment manufacturers maintenance manuals, description and dates of the water treatment program, inspection dates, MSDS documentation on all treatment chemicals, equipment repair records including dates, system water volume records, and the names and phone numbers of individuals responsible for system start-up, maintenance and shut-down.

Cooling Tower Locations Recommendations (Guideline 12)

* Locate cooling towers far from fresh air intakes and windows that can be opened.
* Consider prevailing wind direction and don’t locate upwind or upstream of outdoor public areas.
* Don’t locate in areas that can contribute debris and organic material.
* Consider the direction of prevailing winds and don’t locate upstreamof any outdoor public areas.
* Consider future construction, including that on nearby sites.

References: Center for Disease Control – December, 2000 Article, MMWR – July 1994, National Institute of Environmental Health, American Society of Heating, Refrigerating and Air Conditioning (ASHRAE)

Air Solution Company developed and patented the first Air Intake Filter specifically engineered to mount to the outside of cooling towers and other HVAC equipment for purposes of stopping the debris before it entered into the system. Since that time, Air Solution Company has been manufacturing and has introduced a variety of other innovative filter systems including its new Fine Mesh Filter which is engineered for use on small and medium size refrigeration coils and machine fan intake housing units. Air Solution Company Randy Simmons is with Air Solution Company, author of articles can be reached at http://www.airsolutioncompany.com

Here in the Phoenix metropolitan area, adverse water conditions require intelligent water treatment strategies to adequately maintain water cooled equipment. Proper management of the characteristics of the cooling tower sump water along with maintaining good tower hygiene in general accomplishes at least four positive things.

1) It avoids wasting excess water.

2) It inhibits scale formation.

3) It controls biological growth.

4) It reduces the corrosion rate of metal parts in the tower.

Let’s discuss how a cooling tower operates to understand why proper water treatment is important.

Most residents in the valley are familiar with an evaporative cooler. Water from the evaporative cooler sump is circulated by a pump over pads in the evaporative cooler and outside air is drawn through the pads. As the air is drawn through the wet pads some of the water evaporates and cools the air. The cooler air is then circulated into the space where cooling is desired. In the process of cooling the air, the water being recirculated across the pads is also cooled.

That is exactly the same principle being employed in the cooling tower, but on a much grander scale. Rejecting large quantities of heat from a building’s mechanical system requires a lot of water to be evaporated. For example, a one hundred ton water cooled chiller operating at full capacity for 24 hours would require the evaporation of more than four thousand gallons of water. That brings us to the subject of the characteristics of the make up water. Make up water is the water supply that replaces the water being evaporated in the cooling tower.

Here in the metro area, water conditions vary widely because our water comes from several different wells as well as surface sources. The water quality may change rapidly over a short period of time because different sources are utilized for the water supply. Each well has different water characteristics and they often vary widely from one side of town to the other. Water that comes from surface sources, like the Central Arizona Project will usually have significantly different characteristics than well water. Surface water quality may also be influenced by weather conditions such as drought or increased runoff.

As water evaporates in the cooling tower all of the non-volatile components stay behind in the sump of the cooling tower. There is actually a lot more in water than what we would call hardness (carbonates). There are also chlorides, suspended dust particles and biological microorganisms. As more and more water is added to replenish the water that is being evaporated, these dissolved and suspended components in the sump water continue to accumulate. If no measures are taken to control the concentration of these components in the water, the solution eventually increases in concentration to a point where “stuff” starts coming out of solution. This “stuff” ends up getting deposited on the surfaces that the water comes in contact with.

Have you ever seen an evaporative cooler where the pads haven’t been changed for a long while? I’ve seen them so encrusted with mineral deposits that the blower could no longer pull air through them. I’ve also seen them produce a bounty of biological growth in the sump water. That is exactly what will happen in a cooling tower without adequate attention to hygiene and an appropriate water treatment strategy.

When solids that are dissolved in water come out of solution they are deposited first on heat exchange surfaces and surfaces where the water is being evaporated. Heat exchangers, water cooled condensers, drift eliminators, the tube bundle in closed circuit cooling towers and the fill in open cooling towers are a few examples of surfaces where this occurs.

Deposition of mineral scale, dirt and biological fouling on any heat exchange surfaces can result in reduced heat transfer, reduced tower efficiency and increased energy costs. While reducing deposition of these is important with regard to the cooling tower, it is absolutely critical to avoid scaling or fouling in the water cooled condenser. Scaling and fouling in the condenser significantly reduces heat transfer capability and will seriously impact energy costs, performance and reliability.

A two part strategy is usually employed to manage the mineral content of the sump water. Part one is to maintain the sump water pH within allowable limits and to feed the correct type and amount of chemicals to help the water keep more of the dissolved solids in solution. Part two is intentionally sending some of the sump water down the drain (blow down). Blow down reduces the highly concentrated mineral content of the sump water by diluting it with the fresh make up water being added to replace the intentionally wasted water.

Biological growth can also become a significant health risk depending on the particular organism involved. Allowing mud and biological growth to accumulate in the sump of a cooling tower can accelerate corrosion of the sump and shorten the life cycle of the cooling tower. It can also provide a haven for microbes to escape the effects of a biocide.

Proper water treatment strategy and good cooling tower hygiene is not a one size fits all solution. The quality of the make up water will require an adjustment of the type of the chemicals and biocide utilized. It may also require changing feed and blow down rates for proper control. In addition, these requirements may be altered by the characteristics of each individual cooling tower installation.

According to Alan Bateman of DB Water Technologies, there are several things a good cooling tower water treatment program should address in order to be effective. They are total dissolved solids (TDS), hardness, pH, chlorides, suspended solids, an appropriate method for biological control and a proper blow down strategy. Each cooling tower manufacturer publishes recommendations for maintaining proper water conditions of the sump water. The advice of a qualified water treatment professional is advised to ensure that each item above is included in your overall strategy for cooling tower water treatment.

Evaporative air coolers include a system of cooling in which the evaporation of a liquid, typically into the surrounding air, cools the object or a liquid in contact with it. There are number of evaporative designs that people can purchase.

* Direct Evaporative Coolers – this open circuit is used to lower the temperature of air by using what is referred to as a latent heat of evaporation, changing water into vapour. The energy in the air does not change. During the process the warm dry air is changed to cool moist air.

* Indirect Evaporative Cooling – This is a closed circuit system. It is similar to a direct evaporative cooling system. However in this case some sort of heat exchanger is needed. The cooled moist air never comes in contact with the conditioned environment.

* Two-stage Evaporative Cooling – this system is also referred to as an indirect cooling system. This is a traditional system of cooling that uses only a fraction of energy of vapour compression air condition systems. There are drawbacks to using this system however as they tend to make the air very humid which can make people very uncomfortable.

* Cooling towers – cooling towers are structures that are used for cooling water. This process works in a similar way as the evaporative air cooler system. Cooling towers are typically used on large and tall buildings or in industrial sites. They work as they transfer heat to the environment from chillers, for example in the Rankin power cycle.

Housing and smart houses. I believe that we could have avoided this upcoming Natural Gas Shortage by building smarter and more efficient homes. For instance by using small devises which are simple such as using the idea of mini-hydro pumps, reflective energy boosting solar efficiency by 2.5 from a water pond (with 1-2 inches of water covered by a polymer substance of a couple of molecules and a reflective bottom surface), condensation and gravity. These small things can improve the energy efficiency by 10-fold. Here are a few things; this is how I propose which could be done.

Put in a pond which has a reflective ceramic bottom and is filled with water of 2-3 inches depth out side of the house on the East side. The sun comes up and reflects off the water onto a side of the house which has a convex/concave lenses shaped glass window facing 30 degrees as an over hang off the house. On the other side of the lens enclosed is a shaft where the air is heated.

The pond is connected to the inside of the house and the water evaporates up as the air heats up to the roof. The top of the roof on the inside of the shaft is at a 45 degree angle, as the water cools it follows the roof line down the other side of the house through small wheels at each floor providing electricity and running your mini-hydro pumps. The sun coming up on the water is reflected increasing your solar power by 2.5 as you stated and is further magnified by the lens window. The air stays hot in the day and the water roiling back down is used for heating, and electricity for lighting, etc. When the pond freezes in the wintertime you will still have your energy.

Another innovation for this project would be to use those small spheres ceramic glass coated beads, that look like ball bearings look like shiny golf balls in a chamber around the lens area, so that at night they can cover the lens and keep the heat in, these would be enclosed in a pain of glass covering the lens window. Due to the little amount of moving parts and the pure physics and mechanical nature of this without adding any complexity, it should be trouble free forever pretty much.

The only other way I can see this working is to use a “U” shaped water pool with a membrane in it on one end, then dropping in one side concentrated crystal layers, which would attract the water past the membrane and such the water into the one side rising the water level and then using that raised level to flow back to the other side through small hydro-pumps. The membrane could be easily constructed something like a tempered solute mono layer at a lower level of the house and the remaining heated water continues upward in a condensation cloud which would cool later and provide more hydro when the temperature cooled in the top of the shaft of the tower. I do not believe this cannot work.

The pond at night would also provide a starting point for the heating and allow you to use less energy for hot water cooking and showers in the house, giving you a head start of about 100 degrees since heating water is usually the most energy consuming.

One last thought, the spinning wheels could be connected to a sound machine creating a hi-pitched sound, focusing the sound wave into a steel tank filled with helium, and as the helium heated up the molecules would bounce off each other creating friction and heat to make steam to super charge the water in the winter within the bottom of the tower if your pond became iced over. Also it is a good way to make additional energy for heating the air, with fans at the top of the tower you would be able to heat the house too by blowing the heat into floor vents you talked about.

Mathematically this is all feasible, based on an article I read in Modern Solar Magazine about the 2.5 times increase of solar radiation of Beta and Alpha particles in water reflection. Just some thoughts on the designing of an energy efficient home and it’s design. The house it self as long as built efficiently would have no problem being nearly any shape you need. Tri-level would be best for my design, although it does not matter as much the outside shape. I recommend an article in;

Infinite Energy Magazine

Volume 8, Issue 43, 2002

Popular Mechanics

“Heating and cooling towers”

1993 Nov.

The rest of these ideas were from comments heard from the World Think Tank, Naval Survival Techniques of converting ocean water into drinking water by use of a small condensation devise and listening to you talk. One further thought is if you use ocean water and put it into the down flow system and use one of the hydro wheels to speed up the water and cross fire it against a heated stainless steel plate, you could purify the water by RSD Distillation and actually have all the drinking water you needed which was desalination, by simply introducing the small cross fire system somewhere in the water flow from the top of the house. All you need for flow is gravity and you would be slowing the water down by using the wheels to make hydro for the mini-hydro pumps with the salt water and using the distilled water from the top of the house to carry away the contaminants of the ocean water.

You could make about 50 gallons a day pretty easily. Would I live in such a house myself? Well probably not, but for those who live in the sticks or are concerned about occasional power outages or costs. Or those who are paranoid about the future of mankind and his ability to generate his own power, well then this exercise of the brain is not a waste. If you have any ideas on this email me, always interested in such ideas, after all we may need to use these techniques when we build facilities on the Moon or on Mars and certainly they could be of use half the year on the North Pole?