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Legionnaires' Bacteria Reemerges In Previously Disinfected Cooling Towers
schwit1 writes with the New York Times' unsettling report that 15 water-cooling towers in the Bronx that this week tested positive for Legionnaires' disease had been disinfected less than two months ago.
From the NYT: After an outbreak of the disease killed 12 people in July and August in the South Bronx, the city required every building with cooling towers, a common source of the Legionella bacteria that cause the disease, to be cleaned within two weeks. ... [The] city found this week that bacteria had regrown in at least 15 towers that had been cleaned recently in the Morris Park section of the Bronx. The testing occurred after a fresh outbreak in that area that has killed one person and sickened at least 12, and spurred an order from health officials for the towers to be disinfected again.
So any disinfection must be followed with a permanent antisepsis program, say a little copper in the water?
I work in legionella management in the UK, cooling towers must be disinfected every 6 months, no shit the legionella came back, it's present everywhere in the environment. The US has very lax laws for public water safety, see also New York's hideous water towers/roof tanks
Aren't there numerous strategies for preventing this, including adding more chlorine to cooling water in-house?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I believe these refer to cooling towers used for air conditioning, from context. These are more efficient versions (if I understand it correctly) of the compressor (the box that's usually outside as part of a normal two unit home air conditioning system), that use water evaporation to cool the system.
You are not alone. This is not normal. None of this is normal.
This is so typical of the Republicans.
This is the worst variation of the "Kevin Bacon Game." It's the Six Degrees of Political Connection, where any topic, no matter how neutral or broad in scope (like naturally occurring bacteria) can be linked to any political opinion.
Wasn't it Jim Gaffigan who pointed out the way to stop a conversation was with, "I'd like to talk to you about Jesus"?
Now it's, "I'd like to inject my my politics into whatever you just said."
Pretending this is my office full of bitter coworkers..
Speaking at a hastily-called press conference only a few hundred miles from the buildings in question, Tower-cleaning specialist and former Volkswagen Vice President Gesundheit Krappstadtz stated unequivocally that all cleaning and disinfection operations had been performed with full attention to the requirements of New Jersey's famously strict environmental regulations.
I've calculated my velocity with such exquisite precision that I have no idea where I am.
Air conditioning. You have a heat pump that removes heat from the occupied space and that removed heat is taken away by the water. The cooling tower then cool that water.
The alternative is to remove the rejected heat directly using air. That's what "in-window" air conditioners use, as well as many smaller AC units. In large buildings, however, it's often very difficult to cool the machines directly with air.
=Smidge=
... do they use, if any ? Nalco, Betz, Evoqua are big national brands. What changed? cost cutting, the organics into the water, management/technical experience
What exactly do these cool? Do they cool water or act like an AC?
I've been managing facilities and staff to maintain cooling towers for years. I've personally cleaned them, I've personally maintained them, and I've personally been responsible for the water treatment/chemistry as part of their operational and preventive maintenance.
The answer to your question is, they technically cool water, which is then piped back into a building(s) and used as a "heat sink" for any air conditioning/refrigeration equipment inside the building. In your home air conditioner, you have the box with the fan that sits outside. This box is called the"condenser". The condenser's job is to release any heat that is removed from inside the house. In that type of mechanical refrigeration, the refrigerant (R-22, colloquially called Freon) is compressed to allow for a controlled evaporation cycle inside the indoor unit (the evaporator). As the refrigerant absorbs heat from inside the home, it is pumped outside to the condenser where it releases the head into the air (in this case, the outside air is the "heat sink"). That is, the fan on the condenser pulls outside air across the coils where the hot refrigerant is being pumped, and the heat transfers to the outside air, cooling your house.
In large commercial applications, it is often more efficient to use water based systems to achieve this. In this method, the refrigerant that has absorbed the heat from inside the facility is dumped into what's called "condenser water". The water absorbs the heat, and the cooled refrigerant goes back to the air conditioning systems in the building to absorb more heat. The condenser water is pumped up to the cooling towers where it is filtered through several screens while large fans pull outside air across them (similar to the home system). The combination of the water flow patterns, air velocity, and evaporation will cool this condenser water, allowing for it to be sent back to the indoor air conditioning systems so that it can absorb more heat and start the cycle again.
I mention all of this to say this: the ONLY reason this type of contamination is happening is because of improper maintenance. Period. Water treatment systems are just about idiot proof. So, while we may not hear about it, I guarantee someone, somewhere took a short cut. Maybe it was the end of the fiscal quarter and someone was under pressure to save money, so they postponed the delivery of the aquastat chemicals for a couple of weeks to make budget. Maybe a maintenance engineer didn't really do his rounds inspection that day and so he didn't see that one of the chemical feeder pumps had tripped out on overload. Maybe the maintenance workers didn't want to spend a few hours inside one of these steamy boxes cleaning out additional algae buildup. It's not a glamorous job to say the least, but not terribly difficult in the grand scheme.
People should not only lose their jobs and licenses for this, people absolutely deserve litigation for this. This is nothing short of negligence.
because it provides a good environment for them. It is not at all surprising that the bacteria would be found in a recently disinfected cooling tower. The only way to stop that from happening is to somehow make the cooling tower environment a less friendly one for the bugs.
They still use a compressor, but instead of running normal outside air across dry coils, they run the air across wet coils. The evaporation makes the coils cool faster and more efficiently, at the cost of losing water. The non evaporated water is reused and pumped back to the top. Because the water is reused it can get kind of nasty and needs frequent cleaning. (Note I'm a licensed technician, but I don't work on cooling towers).
Question: if it's providing a heat sink for the cooling system, how is it infecting people? Isn't the chilling process a closed loop? How is the cooling tower water making it into the facility air? Explaining that would be illuminating, and I appreciate what you already wrote.
--#
Sure, no problem. there are closed type systems, but when you have Cooling Towers, it's an open system. That is, there's a secondary chilled water loop that circulates inside, and it dumps its head into the primary loop through a plate and frame heat exchanger. The primary loop gets pumped out to the cooling towers, where it goes through the cooling tower "fill" which is a scheme of different diverter surfaces to separate the water into thin streams running along flat surfaces. Outside air is then drawn across the fill, and that removes the heat and aids in evaporation of the water. Any water that is evaporated away is replaced with fresh "makeup water".
:-)
As the water is being drawn across the fill, it starts to evaporate and also atomize (meaning that the streams of water break up into tiny droplets that are technically still liquid, but are light enough to be carried away in the moving air stream). As these water droplets are pulled into the outside air, they can be carried anywhere. Often, cooling towers are located on the roof of buildings. The other thing that you'll often see on the roof is the building exhaust fans and the fresh air make up fans. If the fresh air makeup fan inlets are located anywhere near the cooling tower, it is very possible to have those same tiny water droplets get sucked into the intake, and pumped into the building along with the fresh air makeup.
Mechanical Engineers usually design the location of these intakes to be far enough away form the Cooling Towers to prevent infiltration, but wind currents can be a little hard to predict. Also, if the Cooling Tower isn't being operated correctly, there can be more water atomization than there should be. For example, if the Variable Frequency Drives (VFDs) that control the Cooling Tower Fan speed isn't set up right, it can run too fast and pull out more water droplets than it should be (this should ordinarily be kept to a minimum because makeup water isn't cheap, and it's not "green" to use too much water).
Hope that helps.
The only effective sterilisation regimes include mechanical abrasion. Good old fashioned scrub brush and soap, plain and simple. I have personally observed bacterial colonies survive under a 95% ethanol solution for over a week under their own biofilm protection. It takes elbow grease, you have to scrub all surfaces to be sterilised with mechanical abrasion and soap, only then can sterilisation chemicals or antibiotic agents have any useful effect.
These cool water by evaporating a portion of it and circulating it through the refrigeration equipment, where the water picks up heat, and then recirculates back through the cooling tower. The cooling tower water is used as a heat sink for the refrigeration equipment, most often a Chiller, which chills a separate, closed circuit of water down to around 40 F to 45F, and that Chilled Water is circulated to the air handling units or other air conditioning systems to provide A/C to the building.
The cooling tower can also be used as a heat rejection device for other, non-A/C systems, like generators, refrigerators, etc.
Nuke it from orbit...
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
It's said that the Roman engineers responsible for the construction of a support arch for a bridge or aqueduct were required to stand under it when the support scaffolding (used in construction) was removed. They had a very personal incentive for making sure everything was done properly.
Likewise, the reactor engineers on a nuclear submarine have a very personal incentive for making sure everything is done properly, over and above military discipline.
Do we even know that, in this case, the cooling towers were even properly disinfected in the first place? Maybe the building managers and whoever else is responsible should be required to spend the day after disinfection exposed to a nice mist of cooling water...
-- Alastair
Bleach doesn't work every time.
Bleach, alcohol, etc. need to be applied at specific concentrations for a specific period of time to be effective.
If you don't follow these procedures, all you do is breed stronger shit.
Some retard is lining up right now to say "NOOOOOOOO THEY NEVER BECOME RESISTANT TO BLEACH OR ALCOHOL!!!!".
Plenty of organism have on outer wrapper, or "skin", to protect them from hostile environments. Many micro organisms wall off and go dormant until the coast is clear and then come back. So fuck off with that theory, please.
Bleach doesn't work every time. Not even fire does. However, I suspect what happened here was a simple case of places not being cleaned properly (or at all) because the building owners / maintenance people were cheap / lazy.
Maybe they should try disinfectant this time
Actually it does in the case. Chlorine in the water kills the stuff. The problem here is killing the stuff and walking away instead of putting chlorine in the cooling water and keeping up the chlorine levels. According to a microbiologist I spoke to about this some years ago the amount needed is less than is in drinking water in some places - enough to taste awful but not enough to make it unfit to drink.
You said
The issue is not that the engineers on this site don't understand human nature,
and then went on to completely contradict yourself
its that we don't understand how the rest of society can be so clueless of a clear solution path to our energy needs.
In the case of nuclear power, circletimessquare was mostly right, however he doesn't explicitly state that in the case of nuclear power the problems are greatly exacerbated by the time scales involved.
The length of the fuel-cycle is not just longer than a human lifetime, not just longer than the expected lifetime of a even the longest lived corporate entity, but longer than the likely length of our our civilisation.
Given a presumed understanding of human nature it is obvious to anyone who takes the time to really think about it, current nuclear power technologies are not viable.
With that said it is obvious that something needs to be done about our reliance on fossil fuels, and although many alternative energy sources are starting to look promising they are not quite there yet.
Alternate nuclear processes aught to be considered, thorium reactors seem to be the favourite on this site, the technology might be the greatest thing since sliced bread but the significant cohort of posters on this site that preach the virtues of thorium (or fusion for that matter) without any sign that they have considered that there might also be negative imapacts is ironically the reason that whilst I desipse the narrow minded, unelnightened, and ignorant management class that runs our businesses and our societies I still prefer that they run things than a bunch of (fellow) engineers.
With an IQ of 144, I just have to remind myself that 100 is the average, with half the population below and half above
This doesn't help you argument either; it never ceases to amaze that people who are clearly intelligent and work with numbers can place faith in an obviously flawed pseudo-scientific "measurement"
Andy Warhol got it right / Everybody gets the limelight
Andy Warhol got it wrong / Fifteen minutes is too long.
Bad form to reply to myself but I should point out that I mostly agree with the AC I replied to above but his/her post typifies what I believe is the biggest problem we have as a society/civilisation; we are experts in ever increasingly narrow domains of knowledge and are not just profoundly igonorant outside of that domain but as a result we are incapable of understanding our collective shortcomings or syntheisising sustainable solutions to address them.
You said
The issue is not that the engineers on this site don't understand human nature,
and then went on to completely contradict yourself
its that we don't understand how the rest of society can be so clueless of a clear solution path to our energy needs.
In the case of nuclear power, circletimessquare was mostly right, however he doesn't explicitly state that in the case of nuclear power the problems are greatly exacerbated by the time scales involved.
The length of the fuel-cycle is not just longer than a human lifetime, not just longer than the expected lifetime of a even the longest lived corporate entity, but longer than the likely length of our our civilisation.
Given a presumed understanding of human nature it is obvious to anyone who takes the time to really think about it, current nuclear power technologies are not viable.
With that said it is obvious that something needs to be done about our reliance on fossil fuels, and although many alternative energy sources are starting to look promising they are not quite there yet.
Alternate nuclear processes aught to be considered, thorium reactors seem to be the favourite on this site, the technology might be the greatest thing since sliced bread but the significant cohort of posters on this site that preach the virtues of thorium (or fusion for that matter) without any sign that they have considered that there might also be negative imapacts is ironically the reason that whilst I desipse the narrow minded, unelnightened, and ignorant management class that runs our businesses and our societies I still prefer that they run things than a bunch of (fellow) engineers.
With an IQ of 144, I just have to remind myself that 100 is the average, with half the population below and half above
This doesn't help you argument either; it never ceases to amaze that people who are clearly intelligent and work with numbers can place faith in an obviously flawed pseudo-scientific "measurement"
Andy Warhol got it right / Everybody gets the limelight
Andy Warhol got it wrong / Fifteen minutes is too long.
Translation: more than enough to damage the equipment.
(plus, it's an added cost, both in time and materials.)
WTF do you get something as utterly ridiculous as that from? If you made it up - why? The difference is several orders of magnitude. The drinking water in my city has a concentration of chlorine several times higher than this bacteria can stand, and domestic bleach is far more concentrated again yet still unlikely to "damage the equipment".
True, but that's life when you are squirting a deadly bacteria laden aerosol into areas where people are breathing. Some expense to avoid doing that is considered tolerable.
Because chlorine is corrosive. In the concentrations one should be maintaining, it's not so bad. But prolonged exposure, even at the "correct" levels will cause corrosion. If you doubt this, take your finest stainless steel butter knife and drop it in the bottle of chlorine bleach; over time, it will rust. Just like a swimsuit will slowly fade (and degenerate) over a summer of being dunked in pool water every day.
With respect, I was teaching engineering students about corrosion before this site even started so unlike you I am not making shit up. The tiny amounts of chlorine required (wikipedia says 0.5 ppm to 2 ppm you utterly lazy creature), as there is in the drinking water in some places, fail to do measurable damage to stainless steel fittings that they come in contact with when used as drinking water. It's nothing remotely close to the amount of chlorine that is in seawater which attacks many different types of stainless steel. It's nothing remotely close to the concentration in a swimming pool. Look it up instead of making it up - that's what I did but I looked it up first in 1990 and have read a bit since. Now it only takes seconds to look it up - wikipedia has it FFS.
So why do you wish to spread such misinformation? Does it give you some sense of power over the kiddies to make them believe something you just made up? They should look for themselves instead of falling for shit from you or taking my word for granted.