Legionnaires' Bacteria Reemerges In Previously Disinfected Cooling Towers 118
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.
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Nuke it from orbit...
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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.
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Translation: more than enough to damage the equipment.
(plus, it's an added cost, both in time and materials.)
Above poster seems to be on acid instead of bleach (Score:2)
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 bacteri
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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.
We are talking drops in the ocean not seawater (Score:2)
Bacteria spread via the air (Score:3)
So any disinfection must be followed with a permanent antisepsis program, say a little copper in the water?
Yeah, I thought this problem was solved (Score:2)
Aren't there numerous strategies for preventing this, including adding more chlorine to cooling water in-house?
Re:Yeah, I thought this problem was solved (Score:5, Insightful)
But, we forgot about lazy, cheap people.
Yes, chlorine or hydrogen peroxidation would solve this, but require some method to maintain the antiseptic aspect.
Copper sheeting might shed enough Cu ions for many years, but would ne replacing as it eroded away.
Newly installed cooling towers deal with this, as this search shows.
https://www.google.ca/search?q... [google.ca]
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Newly installed cooling towers deal with this, as this search shows.
That search clearly isn't showing me what it's showing you, because all I'm getting is a bunch of descriptions of the problem. Pathetically, even the CDC page only describes the problem [cdc.gov], even though the CDC has renamed itself the centers for disease control and prevention. If you actually drill down a couple of links you get to their page on prevention [cdc.gov]... which only covers hot tubs! Your tax dollars at work! No, wait. They're on vacation.
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Dig down, I did cast a wide net.
I found this on page 2.
http://www.hse.gov.uk/legionna... [hse.gov.uk]
and this, more directed search, gives more.
https://www.google.ca/search?q... [google.ca]
but the 2P is correct, this should be a solved problem
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yes, ozone and UV = general cellular toxicants.
Hydrogen peroxide safer but more $$
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But whether H2O2 is more expensive ... a bit thornier a question. Yes, it's a continuing cost for chemicals. But there is a continuing cost with UV for both the electricity to run the lamps, the plumbing and pumps to force the water past the lamps ; the lamps themselves h
Re:Yeah, I thought this problem was solved (Score:4, Insightful)
that's actually the problem with most technology
nuclear for example
i haven't a single doubt that we have the technological means to maintain nuclear plants forever without a single accident
but what we don't have is the social and political means to do that
money is always being cut, indefinitely, and the people making that decision are not exactly technically proficient. the incentive to cut costs form the general public and bosses who want to trumpet cost cutting trumps all other concerns, because other concerns, no matter how vital, are simply not understood. combine that with a technical person that responds with anger and arrogance at the idea of vital safety mechanisms being underfunded, the manager will simply disregard him or her as a person with a personality problem, and then disasters happen
people who champion nuclear, especially on a website like this, understand the technology well, and are correct when they announce we never have to have a nuclear accident ever again due to technological issues
but they don't consider the political and social aspects of our species that means vital funding of safety mechanisms and maintenance of absolutely crucial technology *will* be broken. it's simply a matter of when, not if
and then people who champion nuclear get angry at people like me, and accuse us of not understanding the technology. oh we understand the technology is wonderful. but it is you who doesn't understand humanity
the imperative on cutting costs and doing as little effort as possible is always trumping all other concerns. always. and people like this wind up being the managers, not the underlings. they can't be fired, they do the firing
incompetence is a force that destroys everything. sober up and accept that
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Well, the greatest power for getting rid of lazy incompetent people is the inability of management to keep its power to manage, = unions.
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You mean like what is happening to Walmart?
Re:Yeah, I thought this problem was solved (Score:4, Interesting)
A useful concept here is "Social Tech Level". We have the tech for safe nuclear plants, but we may lack the social tech. Much as, say, Panama had the tech to maintain the canal for many years before it had the social tech. You need both the technical know-how, and enough resources left over after corruption to actually fund it.
For all our competing systems of government, we don't seem to have made much progress in "social tech level" in the past 100 years. If anything, the basic systems of administration haven't improved in this regard, but the skill in corrupting them has gone way up (whether corporate corruption or good old fashioned Old Boys Network corruption).
Whether Socialist, Communist, or Capitalist, each in it's own way we can't seem to get the job done, so I think it's something quite distinct from economic system. I think there's just a problem of administration, transparency, and reporting results to solve. E.g., I don't care if the road gets built by the mayor's nephew, I care whether it's build on-time and to-spec, and how much it cost - if it merely cost more than it should, that's the least-bad problem. Cost-cutting is a good thing, but it takes a back seat to getting the actual job done.
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Chernobyl was unsafe. Aside from that, I don't know of unsafe reactors. Fukushima made some nice drama, but it was never particularly dangerous. Nuclear power appears to be the safest around.
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that's actually the problem with most technology
nuclear for example
i haven't a single doubt that we have the technological means to maintain nuclear plants forever without a single accident
but what we don't have is the social and political means to do that
Actually, a lot of us are simply numerically literate and realize that *every* a) energy source suffers from the issues that you whine about and b) nuclear has a great history despite having accidents sometimes.
Re:Yeah, I thought this problem was solved (Score:5, Informative)
Or perhaps we understand that quite well. And decide that it's not that big a problem.
Civilian nuclear power deaths in the USA, to date: zero.
Military nuclear power deaths in the USA, to date: four? Basically the people in the room with the test reactor (that fit in a bathtub) when someone pulled the control rod (yes, there was only one) out by hand.
Hmm, 70 years of nuclear power in the USA, with so few casualties. I could wish the highways were that safe. Or Airline travel. Or trains. Or COAL MINING. Or Oil drilling. Or even hydropower dams.
Hell, more people have died just this year installing solar cells than have died in nuclear power accidents in the USA in all of history.....
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Minor nitpick: There were only 3 people in the room when they pulled the control rod out, and it wasn't the only control rod. Unfortunately, it was the center rod, and in the reduced power state they had the reactor running in, it was by far the most important control rod. It also didn't help that the rod was removed quickly, probably because it had become stuck and they had to yank on it to free it (though there was no way to confirm that).
https://en.wikipedia.org/wiki/... [wikipedia.org]
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We understand humanity. You don't understand statistics. When there's a nuclear accident, it's big and scary and gets reported by all the press. When there's a coal, wind, or solar accident, it's small and doesn't get reported by the press. If you base your statistics on what's reported on the news
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More simply, the lowest tender rarely produces good results. Just because they contracted the lowest tender to clean the towers does not mean it was actually done. So they tendered for a piece of paper saying it had been done and someone went up there and drained the system and immediately refilled it. Incompetence is not as destructive as corruption and corruption is what always gets incompetence in the door, greed driven stupidity.
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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 we
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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 [slashdot.org] 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 h
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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 [slashdot.org] 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"
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Just having copper in the system won't kill legionella; it can live in copper-piped water systems just fine. Active copper-silver ionization will, but that requires active maintenance, as does every other effective method for treating legionella (UV, ozone, Cu-Ag ionization, chlorine).
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yes, once a film forms, copper is not effective. new copper or silver ions must enter the water at a steady rate.
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This particular bacterium can hitch a ride inside amoebas so it can become a little more resistant to chlorine because of that.
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Perhaps coat the vulnerable surfaces with copper? If it's too expensive to provide electro-plated ducting, then spray some copper-rich paint onto the relevant parts.
It works for sailing ships. Don't know if it'll work for this particular beastie.
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Quite doable, but they must make the cure last the life of the tower, so as the copper erodes, new copper is needed.
In any event, there are many smart ways to make sure there is no continuing infection.
The laziness of people can undermine anything
Re:Bacteria spread via the air (Score:4, Insightful)
The lazy people are almost certainly not personally affected in this case. Ultimately the responsible parties here are landlords who don't properly maintain their buildings, and very few of the landlords who own buildings in the South Bronx actually live in the South Bronx themselves.
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In other words don't overlook the human element in any plan that requires 100% efficacy.
Re:Bacteria spread via the air (Score:5, Informative)
The idea that you can actually 'disinfect' something in the real world, outside of a cleanroom or high end operating room, for more than a few minutes to hours is mostly a polite fiction. Any sort of real world plumbing arrangment is going to be hosting assorted biofilms and other incredibly durable bacterial reservoirs more or less inevitably. As the massive success of modern sanitation systems has proven, you can get water 'clean enough' for the more-or-less-healthy to stay that way; but if you actually need to exterminate almost all the bacteria, you are picking a whole different fight.
If, though, you only need to ensure that the contents of the droplets emitted by the cooling system in operation are reasonably disinfected, intense UV in the outflow ducts might be able to do that, and UV isn't high energy enough to do too much violence to metal parts(plastics/rubber/etc. can be trouble; but you won't be commiserating with nuclear reactor operators over radiation embrittlement issues.)
Re:Bacteria spread via the air (Score:5, Insightful)
You said the key word there: Biofilms
Odds are that they never actually (or fully) disinfected the system. A lot of bacteria remained, sheltered by biofilm, and disinfectants are proven to be ineffective against biofilm. After they "cleaned" it and checked the bacteria levels, it was just a matter of time before the biofilm naturally continued releasing the bacteria...
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Proper antibacterial design, with maintenance, never provides a growth medium for whatever bacteria the winds bring in = no films in the first place. Sadly, human nature and bad maintenance = eventual fail mode = biofilms and mats can form that constantly shed bacteria into the air flow.
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Potable water systems, made of copper, which have never had anything but potable water go through them STILL get biofilms on them.
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Yes, it depends on the anti-corrosion additives that are in the water. The proper ones block copper oxidation. Back when I was a young engineer, we had a boiler system that was protected this way, and we took samples evry month and sent them off to the boiler chemical company, who then sent us a list of actions to rebuild the additive prifile.
I expect external cooling towers are much the same, as this search reveals.
Just text to schedule, add the chemicals and all is well.
https://www.google.ca/search?q... [google.ca]
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"intense UV in the outflow ducts might be able to do that"
And the easiest way to prevent UV embrittlement of plastics is to use stainless steel where the lights are. That's a solved problem.
The issue is that a lot of these installations predate disinfection requirements and/or management cheap out by not replacing sterilising lamps or skimping on the sodium hydrochlorite purchases.
There need to be criminal penalties and personal liability for lax processes when it comes ot public health issues. These have a
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I spent a summer working for a place that had oh, 15-20 towers. TWICE a week we dosed the tower with biocides and rust preventatives, and once every 2 weeks samples from each of the towers went out for analysis. Then again, I know from my father, who worked in the field, the place I was at was 'odd' in that we did way more PM than any other place he knew of (he was in the repair end, I was doing operating). Sounds like the places with the problem aren't putting in the money. The problem with tower water
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Yes, maintenance, bactericide, algaecide have to be a well oiled routine, especially in the summer time
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We were insane. Every machine room was swept daily, floors stripped and waxed 1x/week (in the machine room!!), readings and wipe down of the machines was done 4x/day, so you could see if there were any leaks etc. Spares were labels and neatly hung. Each machine room had a spare TOWER and spare compressor in line - just open valves, and turn on. Building also ran at 100% fresh air, all electrostatically precipitated. Yes, the building was a virtual clean room. Did I say we were a BIT crazy?
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Ever vigilant, must have been a union shop
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Re: Cooling towers (Score:2)
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).
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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=
Re:Cooling towers (Score:5, Informative)
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.
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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.
--#
Re:Cooling towers (Score:5, Informative)
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.
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The cooling to
Uk legionella engineer here (Score:5, Informative)
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
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Does UV work against legionella? Installing UV-leds citywide should be easier than the lost cause of trying to get irresponsible building owners to do their part for the society.
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I don't think he meant out on the streets. I think he meant in pipes where no-one will get a tan.
Or are you worried about UV photons in your water supply?
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You would put UV sterilizers into the cooling water systems, not just into the water supply in general. Cooling tower water is pumped in a circle. Add in a sterilizer. Problem solved, maybe? Or maybe not. So the question still stands. Does UV work on this stuff?
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You would put UV sterilizers into the cooling water systems, not just into the water supply in general. Cooling tower water is pumped in a circle. Add in a sterilizer. Problem solved, maybe? Or maybe not. So the question still stands. Does UV work on this stuff?
It's the most common way of being a douchebag - never considering "that must not be what he meant since it obviously wouldn't work". A douchebag prefers to think "hah he sure is a moron, even though there's multiple ways to interpret what he meant and at least one of those makes sense!"
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If you'll pay attention to the thread, the remark that originated the discussion was:
Installing UV-leds citywide should be easier than the lost cause of trying to get irresponsible building owners to do their part for the society.
This means to me, not in the cooling towers, but some other solution for the whole city, even leaving aside the question of the method, it's clearly a very different sentiment than concerning ourselves about mechanisms used in the individual towers.
Re:Uk legionella engineer here (Score:4, Interesting)
Yes, but LEDs don't go low enough on the spectrum. The lamps they use for ponds are gas discharge and don't last very long.
If you really want to generate UV it would make more sense to use spark discharges in the water. Generates a lot of UV, destroys bacteria due to electroporation, removes charge from particulates and decreases the size of particulates through shockwaves (also your electrodes of course, but those are cheap to replace).
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Yes, but LEDs don't go low enough on the spectrum.
Incorrect, power LEDs are now manufactured down to 200nm wavelengths and lower. You only need light peaking around 254nm wavelengths to sterilize.
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I stand corrected.
Still, I really like the concept of just blasting it with a Marx generator.
Re:Uk legionella engineer here (Score:4, Funny)
Dunno, bathing the entire city in a 1970's UV glow has a certain appeal. You could bring back bell-bottoms.
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Just trying to move the conversation forwards, I'm already arguing on G+ with someone with poor reading comprehension who thought I was arguing against socialism.
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It would work if you could cover every inch of the inside of the air ducts, which you probably can't. I doubt it would have any effect at all on fast flowing air.
Nope. You would have to use Ozone, if even that works. Then you get into the position to having to make sure you're not making too much, but that seems solvable.
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http://darksky.org/light-pollu... [darksky.org]
Re: Uk legionella engineer here (Score:1)
I've not seen uv used on cooling towers, usually high powered uv lamps are used on boreholes and surgical/pharma systems, closed stuff, but not something as crude as a cooling tower sump. Normally sumps are just chlorinated, but the sump water has to be changed every now and then as evaporation concentrates the chemicals which corrode the tower
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I'm a student at one of the schools in the current outbreak. After the previous one in the South Bronx a month or two ago, the city required all cooling towers to be disinfected within two weeks. So these towers were disinfected, but Legionella came back nonetheless. Is that common?
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Yes. Legionella is everywhere. It's a common soil bacteria.
Disinfection only lasts a short time and the bacteria is commonly brought in on the soles of shoes.
Many of the rooftop sites I worked on (radio masts) had strict procedures about working near cooling towers, including a requirement to wear clean-room overshoe booties whilst outside and in plantrooms to try and avoid contamination from this vector and _no_ sites allowed public roof access - the roof doors were usually pretty solid assemblies.
Re:Since they knew it would come back.. (Score:4, Insightful)
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."
Reassuring the public... (Score:3)
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.
which contract water treatment companies? (Score:2)
The bacteria are found in the cooling towers (Score:4, Interesting)
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.
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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.
I know! I know! Put a politician, preferably fairly high level (they get more dangerous as they age) in the tower. That's a pretty unfriendly environment. If it's a bad infestation, you can temporarily install a committee. Monitor everything on C-Span.
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"The only way to stop that from happening is to somehow make the cooling tower environment a less friendly one for the bugs."
Like disinfecting them, as was recently done?
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Disinfecting them makes them more attractive because there is now less competition!
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Disinfection, alone, is a bit like kicking some hobos out from under a bridge. Without further action, they'll just be replaced by more hobos.
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I was thinking more along the lines of chemical additives to alter the pH or shifting the temperature range at which the things work, etc. Bacteria need a source of food of some sort. It might be possible to identify it and eliminate it from the towers. Maybe they consume fungus. If you can stop the fungus you stop the things that feed on it.
Biofilm (Score:1)
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.
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What about pressure cleaning?
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Doesn't seem like a great idea given that legionella is mostly hazardous when it is carried by airborne water droplets that can be breathed in.
This time (Score:2)