Blind Angel - 18-11-2006 at 18:01
We were wondering how to kill all bacteria into a drain pipe (the one around the house) because of Iron Ochre deposit. We first though of using NaOCl
solution but due to environnemental regulation we can't use any chlorine-derivative bactericide. So my choice is on H2O2 for the moment.We would first
wash the pipe with water then using a low pressure sprayer we would spray H2O2 in them. Here are some question:
1) What is the minimal contact time for most bacteria to die under the effect of peroxide
2) Related to #1, would 6% H2O2 be sufficient or a more concentrated solution would be necessary
3) We are talking here of about 15l of Peroxide solution which would end up in the soil or maybe in a creek, wouldn't that be domageable for the
ecosystem (soil vs. creek)
I would be very grateful if you could give me some info on this subject, please feel free to drop in idea if you have any too.
Thx
enhzflep - 19-11-2006 at 02:59
Just a few thoughts..
1) Do we know which bacteria we're dealing with?
2) Without answer to #1, a bit hard to answer. 3% H2O2 is sold as a disinfectant for humans, so at 6% it'll certainly kill..... something.
3) Hydroponic systems use H2O2 (couple of mls per ltr) as an oxygen provider and as a disinfectant. So long as the peroxide isn't too concentrated,
the plants'll only get bigger 
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NOTE: I may be completely out of my tree here, but I'd be cautions about tipping 15L of H2O2 into a relatively sealed system. I mean, should it find
something it doesn't agree with, and subsequently decompose. At 3% you'll suddenly be faced with 300L of extra gas. 6% -> 600L. 12% ->1200L etc.
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Nerro - 19-11-2006 at 03:42
I suppose flushing the tube with a solution of a couple of grams of CuSO4 is out of the question too?
Blind Angel - 19-11-2006 at 04:34
The system isn't seale, it's an absorbing drain, it's a semi porous plastic tube (the one wich is rippled) which absorb and then reject at the end the
water. We are talking here of about 60 meter (~200ft) of 10cm (4inch) tubing. It might be possible to flush the tubing but it'll be easier to just
spray in since the flow rate isn't very constant and it'll be hard to calculate how much water would be required to fill the pipe for a said amount of
time. The tube is underground and we don't really want to excavate it.
The bacteria that we are talking about are long filament Iron deposing bacteria from what I can read, they are mainly from the genus Gallionella,
Leptothris, and Sphaerotilus. To a lesser extent they are some rod type too: Pseudomonas and Enterobacter. I don't think that they are very resistant
to oxydant, I might need to check that further when I'll have time though.
Nerro - 19-11-2006 at 05:22
How resistant are most bacteria to just plain ol' soap? I'd expect it to wreak havoc on their cellmembranes.
Elawr - 19-11-2006 at 19:56
You could use a chelator such as EDTA, or even Calgon. Make the Fe unavailable to the bacteria, and starve the little buggers.
Twospoons - 19-11-2006 at 20:32
I'd have thought H2O2 would be about the most benign bactericide you could find, with regard to persistance in the environment. The iron from the
bacteria will probably make the peroxide decompose anyway - which is good, if the peroxide doesn't kill them then the heat certainly will! ICI make
30% peroxide as a 'shock' treatment for swimming pools, for use with the Bacqacil pool chem range, should you be looking for a stronger source.
Blind Angel - 20-11-2006 at 15:23
And what about contact time, how long are we speaking for a good disinfection? I'm guessing rather short, but if anybody has number it'd be nice.
nitro-genes - 20-11-2006 at 16:45
Lipids are very susceptable to peroxidation, altering the fluidity and permeability of the cellmembrane almost instantly. Cellmembranes are freely
permeable for water (changing osmotic potential of the environment will kill them also), so I see no reason why hydrogen peroxide (small molecule,
without charge) shouldn't permeate freely too. Once permeated into the cell it will wreak havoc on all cytosolic enzymes, killing the cell very fast.
Hydrogen peroxide is one of the meanest compounds to have in the cell. Ever wondered why enzymes involving oxidase reactions are located in a seperate
organel? 
Prokaroytes lack peroxisomes completely, so they are even more
vulnerable to peroxides probably...
In general, small chemicals that can permeate the cellmembrane very fast, like formaldehyde, chlorine, hydrogenperoxide or alchohol for example are
the quickest desinfectants...
Of course concentrated NaOH or H2SO4 will do the job also...
[Edited on 21-11-2006 by nitro-genes]
chemoleo - 20-11-2006 at 19:19
Well I'd recommend a combination of a shitload (20-50 l) of 3-6% H2O2, detergent (even dishwasher liquid will do), EDTA, and hot boiling water. The
large volume is required to maximise contact time - clearly these bacteria are hardy, so they need a solid prolonged pounding until their cell
membranes crack (due to heat and time and detergent), and then the H2O2 as well as the EDTA finish them of quickly.
The hot water will be important, from personal experience. Also, H2O2, as well as detergetns, are more reactive that way.
gil - 16-12-2006 at 17:55
to Blind Angel
didyou finish your job already? I ask this because I presume I'm too late. If this is not the case, or if you did but you are not 100% happy whith
results, then have a look at this;get some sand/protozoa mix from a cold pond/lake/river by diggin' 1 foot to reach the fine sand.Fill up a bucket
sieving out big bits.pour this sand/amoebae mix trough your pipe using a funnel.Follow it(or mix to last portion of sand) whith 3 or 4 kg. of sodium
bicarbonate if you like and have a beer/treat whith the two dime you spared. prefill the pipe+mix sand x
make it runny helping whith some extra water help prevent blocks. Leave few hour/more before add bicarb,if choosen.I would keep it as a last option.
the organisms will suffice.It does for Earth since 2.000.000.000 b.c and
some of those organism are able to carry away incredible quantity of particulates,like a snowball downhill; also they find most filamentous bacteria
and all that biofilm stuff very appetising.Try it!?
Blind Angel - 17-12-2006 at 07:13
I'm not sure if this is an elaborate trolling attemp or an idea that I'm just too tired to fully grasp, but anyway there is already 2 to 3 feet of
snow here and the soil is frozen so sand digging is not really and option.
vulture - 17-12-2006 at 14:11
Formaldehyde is preferred over H2O2 if solid desinfection is required.