Best Substance to Keep Non-Drinking Water Sterile?

Contact an industrial water treatment chemicals distribution company, and discuss the problem locally.

The air going into the underground tank will be carrying moisture expired by the plants, and if does condense in the tank like you want it to the tank will fill with water.

Rather than using a chemical approach, since all chemicals pose some risk and will possibly break down at some point losing their effectiveness, why not consider using a UV lamp submerged into the water to purify it? It will control algae and most other nasties and is one of the methods for preventing Legionnaires' Disease.

The prototype I'm currently installing at my mum's house, but yes humidity may be an issue. It remains to be seen whether there will be a net loss or gain of liquid, but I'm leaving an access tube, so water can be added or removed as necessary.

A UV light would do it, but is a bit high tech and electrical for the approach I'm taking. Ultimately I want this to be easily home buildable with minimum resources.

Were are you?

Any of the chemicals you are thinking of using will have some corrosive effect on materials used in the area. And the chemicals get used and converted as they react to the bacteria you are trying to kill, so you need to know how to maintain the correct percentage of chemical feed. Since you are bubbling air through the water, you might want to investigate the use of oxygen as your "germicide". A large mass of very fine bubbles flowing through the water will provide a high contact area for O2 in air to react with the water. Waste treatment plants use this option in part of the treatment of sewage. It will require some degree of pressure to get a good flow rate.

Which brings up another issue. You may want to have some one verify the heat balance in this system. I suspect you will need a higher volume of air than you think to keep the green hous comfortable.

I think USB port has the best suggestion with the UV lamp. It's not as high tech as you think. It's pretty much a lamp connected to a box and that's it. Just plug into the power cord. I haven't seen your blog but some of your other suggestions use substances that will alter the pH of the water, or will be consumed or may react with other substances that may enter the water, so you may have to periodically top up to maintain effectiveness and possibly clean out the tank more often than thought. You just need to decide how effective you want it to be.

In the same vein as Usbport's comment, your water reservoir will be isolated; its only contact with the outside world will be through the air stream. If you pre-sterilize the water and filter the air going through it, that might be the ticket.

Another possibility is an inline ozone generator in the air stream, upstream of the water drum. Ozone decays into ordinary diatomic oxygen so you're not adding toxics to the airstream, but you are killing any nasties in the air with a powerful oxydizing agent.

Ozone can be pretty nasty stuff, I make a factory sick using ozone for water purification. Ozone needs very careful control, and would not be a "low-tech" solution.

I have been using ozone generators for swimming pools and potable water storage systems for several years, with no health problems. A properly sized unit will not cause problems. Excess ozone is very easy to detect in very small concentrations- smells like an electrical arc (which is exactly what you are smelling after an electrical arc- ozone created in the coronal discharge). Ozone is essentially "supercharged" oxygen- O₃ instead of O₂, which makes it a much more effective oxidizer. But it doesn't last very long...

The problem with the UV light is that it is only going to be effective a short distance from the lamp. It will not treat a reservoir, unless you circulate the water through a contact chamber.

Ozone. But generating ozone also requires electricity. Check out http://www.cwtozone.com/

That sounds promising...

I'd have the luxury, since no one will be swimming in it, of using higher doses. Especially if it doesn't put off harmful gases.

I'm currently in Western Australia, but am heading for New Zealand for a couple months on the 25th and will probably set up something similar there in an actual greenhouse.

My mum's place is about 120 cubic meters of air, which would have the same thermal mass (as I figure it) as about 40 litres of water.

For this trial I'll be initially using one 20 litre steel oil drum as the container, but may add an extra one if I need more water mass.

Humidity has been running at about 60%, outside air temp about 30-36. 20ish overnight.

I'd be concerned about toxicity issues with ozone, and is higher tech than I'm looking. Ultimately I'd like to see this as an easy solution for homes and growing spaces that people can easily construct and maintain themselves. So UV is probably out as well.

The water isn't being used for any other purpose, so pH etc isn't a problem.

I don't mind having to top up the chemical every so often, but am not going to be able to test for when it becomes necessary, so would prefer something that I can keep at 'overkill' kind of levels without the danger of gassing everybody.

What are people's feelings on vinegar?

What is the source of the water? If completely pure why the concern?

I used to get water in 5 gallon bottles then forgot some of them. They sat outdoors in Direct sunlight and never gave any sign of greening indication chlorophyll activity. I had been told this was pure water and now I believe it. Ground water in this area is so bad many people buy RO ( reverse osmosis) bottled water.

Unless you contaminate it from the container or by introducing bacteria or microbes via the air injection it will remail in good condition.

If there is anything organic in your water, there is a possiblity that over time, mould may form on the side walls of the tank or float on the surface of the water. Maybe you should trial some of your ideas in small beakers and check for smell, stains, mould/bacteria growth etc... before using your mum as a guinea pig.......or better still, maybe you should use your mother-in-law as the test guinea pig.

on vinegar: like bleach, it could affect your air quality at effective concentrations. It will also contribute to corrosion of metal parts in the system, and metal anywhere in the greenhouse, over time, if it is present in gases and condensates.

Good to know.

It'll just be tap water in the tank, which here is chlorinated, but having all the air in the house cycled directly through it it'll definitely be picking stuff up.

sugarandfat

Just one tiny critique, if you intend to use a wind source to provide the power source to push the air you might want to consider running a longish trial of the wind velocity/pressure at your proposed site. Certainly where I live (UK) there is no guarantee of wind velocity, especially at warm, anti cylconic weather times; just when you need the air conditioning most? You certainly cannot guarantee a continuous supply of air in that way, and may have to add some electical input to keep the system going in such conditions.

The above information may well be available from your local meteorological stations!

Good Luck

Sleepy

For sure. The wind option will be available on supply, with an electrical backup. I'm probably not going to have time to get the turbine going here anyway, so will just be running it from mains power.

It's been record hot here this last month (most consecutive days over 30 (29 days)), and was fairly windy over the same period.

Oh do try to keep up

Would using a hider nickname assist me in keeping up? I think not, I'll stay out here with the men. You stay hidden with the other juveniles.

Cheers

You are as usual lost

AP1 provided a link to Sugar & Fat's previous discussion, which you are welcome to join

This thread has always been about water treatment

"You are as usual lost"

I do believe that you have the solution to your problem at hand already. My suggestion is to employ standard household bleach to disinfect your tank water. It is the cheapest and most straight forward practical way to kill off bacteria. If you go this route just make sure that you purchase a pool water testing kit that allows you to test free residual Chlorine down to 0.1 mg/L (0.1 ppm) and up to 100 mg/L. You want to maintain no less than 0.5 mg/L of free Chlorine residual at all times. Initially. once you fill the tank with water you want to shock disinfect the stored water and maintain no less than 50 mg/L free Chlorine residual for a 24-hour period....longer the better. This will insure that you kill off any bacteria and other organisms in the water itself and any that were present on the inside surface of the tank and all new piping. This is what is done before a new municipal water storage tank is placed into service. If you don't buy bleach buy pool disinfection chemicals such as HTH, etc because it contains Sodium Hypochlorite...a bit more costly (you're paying for the water used to make up the solution + freight costs to handle a heavier product) than bleach, but it is more concentrated too.

Since I do not know the capacity of your storage tank I cannot at this time calculate to required amount of bleach you'd need to provide the shock dosage you're need. I'd also need to know what the standard bleach chlorine amount is down there in Oz as it may differ from what we can buy herein the US.....maybe 6.25% available Chlorine? Needs to be verified!

I do not recommend other chemicals such as hydrogen peroxide, etc due to their costs and inherent dangers handling them...just keep it simple! Remember, KISS principal!

Don't go the route of UV lamps. They're costly, costly to maintain (constant electrical draw), and replacement bulbs are mucho costly. That, and you need to pass the water through a shallow disinfection trough, clear piping, or shallow depth open trench of sufficient breadth and length to be effective...all this means is that you're going to have to recirculate the storage water constantly, which amounts to more electrical demand!

===signed,

CaptMoosie, PE / PhD

Civil, Structural & Environmental Engineer

Copper is interesting...

The water will be constantly circulated by the bubbles, so if I chucked some offcut copper pipe in there the water should be in regular contact with it. But it would have to absolutely definitely kill everything, because I'm not equipped to be testing for pathogens.

Colloidal silver would be the perfect substance for this in every way, it doesn't metabolise / break down, definitely kills everything and doesn't fume. The only and fatal flaw is that you can't keep it in metal containers. The weak magnetic field draws the silver microclusters out of the water. Even if I used a plastic vessel I suspect there'd be enough minerals in the soil to do the same.

Bleach was always an option and may well be the best one, I'd just be concerned about chlorine fumes...

You could use a colloidal silver infused ceramic filter

http://www.filters-machines.com/ceramic-water-filters.html

a more detailed explanation link

the homemade version http://s189535770.onlinehome.us/pottersforpeace/?page_id=125

Potters for peace. Awesome.

There's quite a bit of info there, so I'll admit I only skimmed...

Would the constantly circulating water not eventually wash all the silver from the ceramic?

I can easily pour a chemical into the tank, but anything more involved than that would require digging it up each time.

But I might be misunderstanding you.

The silver [about a dimes worth] is fired on like a glaze

you would need some way to pump the water up to the filter & let it gravity down

there are commercial versions if you didn't want to build your own

it's still going to be tricky since your heat exchanger is going to be under ground, I'm not sure what the equivalent filtering device for the air would be?

Ah, I getcha.

Might be getting a bit tricky..

Um, this might sound real dumb, but why do you need a cooling system for a greenhouse? Couldn't you just use windows and circulate the outside air?

I'm not being a smarta$$ here. I'm sure there's a reason, I just don't know what it is.

It gets very hot where I live, and plants and gardens thrive without artificial cooling. Plants cool themselves through transpiration, much like humans sweat to keep from overheating.

Just a thought.......if the intensity of the sun is too strong, you could use shade cloth to diffuse the light and reflect the heat.

For practices like integrated fish farming it's generally good to have full environmental control, and in greenhouses heat buildup can be a big problem.

Plus places like here, Western Australia, the air temperature can easily hit 40 C a couple days running in summer, and quite a bit higher inland and up north. Even in the shade that'll fry a lot of veggies.

It's probably not the most vital tech, but a few people have mentioned a desire for it to me recently, so thought I'd turn my hand to a solution.

Also, here in summer about 25% of power goes to aircon, so something that can be installed into people's homes for free with no electrics would take a massive strain off the grid.

I understand, just throwing out thoughts. No water with this:

http://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger

At the bottom of this article they mention a brine solution for water systems.

Is it very low humidity? If so these misters are quite effective. Just tell me to shut up if you've already determined that you need a storage tank.

Misters are fine, but yeah, this might want to be used in humid areas.

Ground sinks etc are fine but generally require quite a bit of laid pipe to maximise contact with ground mass. What I like about this design is it doesn't require any adaptation of the existing space. You're just digging a hole and running some hose.

And since water can circulate and has high thermal mass, seems it would be better than earth. Ultimately the heat will end up in the soil, but most of the transfer out of the water can take place overnight.

Guy's PM'd me recommending among other things high concentrations of sodium chloride.

Thoughts?

He also mentioned corrosion..

In regard to the buried water storage tank: provide a 24-inch diameter manway to grade with a solid cover so you don't have to keep digging up soil so as to replenish your disinfection chemicals (if you go that route)....you can make the manway from PVC or HDPE pipe and cement in to the top of the tank.

In regard to the need to cool the greenhouse (this is OT): many greenhouses are equipped with auto-dampers that automatically open several glass panes when the heat inside the greenhouse becomes too hot. It's so K-I-S-S!!!!

Just a few more Pennies thrown onto the Pot....

Burying the thing isn't so much a problem. I'm using garden hose for the airflow, and am going to to be able to unclip the hose from the tank just above ground level. Chemicals can be poured in there and the hose reattached. Will also let me insert a thermometer.

Automated windows etc can and do work fine a lot of the time, but are a bit higher tech than I'm aiming (I also have a potential very basic greenhouse design, here: http://urbangreenhouse.blogspot.com/2010/11/here-is-first-basic-design-for.html ).

Plus if the outside air temp is high enough on it's own to damage your plants, opening a window isn't going to help.

Having a fully enclosed climate controlled space also allows the luxury of controlling your humidity levels.

the link you gave did not work Is something missing?

I got a report saying the page does not exist

Odd, works for me..

http://urbangreenhouse.blogspot.com/2010/11/here-is-first-basic-design-for.html

Or the root site and scroll down

http://urbangreenhouse.blogspot.com

Okay this works. thanks! Last time it was not highlighted as a link and it got word wrapped.

We live in the interior. Summer time temps often reach 32 - 35C so this is something of interest to me as well. We need,the green house to extend the growing season to 4 monts and to avoid the night time frosts which may even hit in june.

I'm hoping the green house will permit me to create a zone3 growing season instead of zone two because that would allow more varieties of foods to be grown.

Cool.

It is worth mentioning too that this system should work as a heater in winter. I don't know what the ground temperature would be in midwinter, but it would definitely be well above zero, so will protect against frosts at the very least.

best way is to use ultraviolet light to keep water sterile, if you dont wanna use chemicals.

So, to sum up so far (awesome feedback yall, thanks heaps)

Probably the two realistic options still in the running would be:

Chlorine; in the form of bleach, hot tub tablets etc.

Pros: lethal, available, concentrations can be easily tested.

Cons: fumes?

and Hydrogen peroxide;

Pros: lethal, available, concentrations easily testable, breaks down into non toxics.

Cons: a little less available than bleach, potentially hazardous to work with if you do something really dumb (but same would be true of chlorine.)

Thoughts? Others?

There is a second con if you constantly disinfect the water with hypochlorite (chlorine) in either wet or dry form. The hypochlorite has an added byproduct of releasing OH ion into the water. That means the pH will climb and depending on the makeup of your water will cause things to precipitate out of solution (calcium hydroxide or metal hydroxides). These deposits will create a gunk on the bottom of the reservoir. To overcome this problem you would have to constantly monitor pH and periodically add acid to correct the pH. Hypochlorites work great on flowing water as in drinking water disinfection and are much more powerful than peroxide as a disinfectant. That means you can use low residuals and achieve a good CT (read chlorine concentration in mg/L times Time in minutes) value for disinfection. Chlorine usually requires anywhere from a CT value of 10 to 20. Peroxide does have a CT but it is just higher and I believe a CT of 200 will provide safe disinfection. Time is very long so CT value in either case will be very large, thus no difference or advantage gained by CT values.

I am not advocating any system over the other. However, in this case I do believe peroxide would be much easier to operate. Technical peroxide has an apparent pH but that does not change the pH of the water..it is neutral. No precipitates by pH change. It should be readily available, even in beauty salons at 8%. Most chemical houses will carry the stronger concentrations and I am sure they will sell small lots. We would buy 65 kg carboys and they would last a long time. You may need a means of transfer to smaller containers for your own use. If you only need a small amount, you could purchase the retailed stuff at most pharmacies or beauty salons. I hope I am not confusing your issue but I wanted to clarify the reason for suggesting peroxide.

That's some really good info, cheers.

Starting to look like H2O2 for the win...

Have you considered copper sulfate?

Looking it up, looks like it's used a bit as an anti fungal. How cross spectrum is it? Any other implications?

You can follow this link and get some info concerning disinfection. My neighbor uses copper ions to treat his greenhouse water. He has about 15 acres under roof and catches rain water and the water runnoff from plant watering in a pond. Filters and electrically adds copper ions. He used to use chlorine gas but got away from that. Someone mentioned in an earlier post adding pieces of cu pipe. Copper Sulfate Pentahydrate is one that is used for disinfection. I might suggest doing a test with water, manure and copper sulfate pentahydrate. Then test for bacteria. If you would like some help with the testing we can work together on that. e-mail me

CR4 Admin - email address removed

From the Site FAQ: Do not post phone numbers or email addresses. The CR4 Admin will delete all phone numbers posted in threads or comments, and we strongly urge you not to put up email addresses. You can share this information via the CR4 internal messaging system.

directly and I will give you more info concerning that. I don't have any specal interest with Aquadrop it is just one co. that uses copper sulfate.

http://www.aquadrop.org/index.php

15 acres? Ye gods.

Testing for contaminants is probably getting a bit more involved than I quite have time for just now, but thanks for the offer.

Copper ions should be easy to prepare, just put two bits of copper wire in water and run a current. And good that they don't break down or settle...

My main concern would be the same as for colloidal silver; that weak electromagnetic fields from the drum and soil would draw the ions out of the water.

But then I guess they're not going to permeate the steel drum, so as the water is constantly circulating, it all should stay in contact...

But seeing as, like someone posted, I'm effectively using my mother as a guinea pig, I'd rather not set out to develop some new process here, and would rather go with something very tried and true.

There are two suggestions that involve copper in various forms. (copper pipe or copper sulfate)

Both of these have significant merit since the "active" ingredient is stable in the water (unlike chlorine and some of the other proposals). Copper Sulfate is used as a steriliser in detention ponds for sewer treatment plants where water with some nutrient is stored for long periods of time before release to various re-use locations.

The significant problem you will face is that no matter what you use, there will be a sludge accumulation that will need to be disposed of. This will be a combination of airborne dust (captured by the water), insects and other contaminants that are in the air stream that you are using, precipitants from whatever cehmical sterilizer you use and so on.

Have you considered using a modest fish tank, including fish (that you could harvest later to eat) as part of the system? There is a "benchmark" greenhouse in Western Australia that was highlighted on "Better Homes and Gardens" around 12 months ago. They were focussed on the water cycle in that place, but seems like it would achieve the same effect that you are after.

Also, by rearing fish, you will have a very strong indicator to the relative "safety" of the water in your system. Bubbling the air through the water would also provide significant oxygenation for them.

Integrated fish farming would fantastic, and is my eventual goal as part of the greater urban farming / aquaculture project. And I did think of using the water store for the fish and/or hydroponics setup for the cold water cooling.

The main issue would be that the water needs to be buried at least a meter deep, which would have implications for its effective integration into other systems. Possible, but will require a bit of thought and work.

At the moment I'm wanting to develop something super simple that is easily made and installed. It also needs to be something that works equally as well for home use, as there's a need for cooling without electricity, the demand on the grid is just getting to high.

Regarding buildup in the water, yes that is an issue. I guess the system can be drained and replaced every so often. Be easy enough to occasionally pump some water through the thing rather than air.

Maybe a filter over the inlet wouldn't hurt either, now that I think about it...

Ok, I declare hydrogen peroxide to be the winner, at least for this first implementation, maybe looking to something more solid state like copper in the future.

So, dosage...?

Keeping in mind that it's 20 litres that shouldn't ever come in contact with anyone, other than released gases, and that I'm wanting to err on the side of overkill and not having to top it up more than necessary. Also, not having to test the concentrations would make things much easier.

I checked in on a pharmacy today, they had 200 ml bottles of 6% (the rest water) for about $5.

To target dose 100 mg/L:

a 1 Liter container of 6% H2O2 contains 60,000 mg

a 200 ml or 0.2L container of 6% H2O2 contains 0.2 x 60000 mg = 12,000 mg

container holds 20 Liters of water to be dosed at 100 mg/L requires 2,000 mg H2O2 (20L x 100 mg/L)

2,000/12,000 x 200 ml = 33 ml of your 200 ml container ( you can over dose to 50 ml). Low cost.

Comment:

20 L container of water may be too small with an ambient air temperature of 30-35 degrees C. The heat from the air will be transferred to the water and then lost to the soil. I am not sure if it will transfer to the soil quick enough and then move away from the soil surrounding the container. You may need a bigger container but I have no idea how big. Just guessing at this stage. If you haven't done so, do some heat transfer calculations.

50 ml. Perfect. Thanks for that.

20 litres probably isn't enough, I think it'll probably be twice that but I'll find out by seeing what happens. I can just keep chucking in more drums til it seems to work.

Next question; how long before I need to replenish the H2O2?

Keeping in mind that I'm erring on the side of too much chemicals.

That will likely depend on temperature and the amount of impurities in the air. But generally a couple of weeks if I use an open swimming pool as a guide. The warmer the water, the faster the residual will be ate up. Usually not a problem till the water gets above 85 degrees F.

A sack of copper turnings in the tank should do.

bioramani

Is that for sure and proven?

Like I say, I want to use something that definitely works.

Be awesome if it does prove to be that easy tho, copper can be got most anywhere and wouldn't need topping up.

Copper ions are known to kill micro-organisms. Systems are availble for doing this actively.

http://poolcaptain.com/656/copper-swimming-pool-ionization/

http://www.legionella-tec.com/gb/TP_gbwhatsion.html

In the case under discussion where there is no human contact involved what I suggested should work. Copper metal immersed in waterdoes release enough ions given enough contact time. There is no need of an active electrolytic ionization in the required application.

bioramani

Yeah nice. When I get a chance I'll have a play with this, it would definitely be the best option.

An update:

http://medtechinsider.com/archives/22207

Bioramani

I would be careful assuming that copper sulfate would be an effective germicide or viral control. It is effective with algae and fungi but less so with bacteria and virus entities. One problem with copper ions is that once it has been bound by protein or other organic components it is no longer effective. You will measure adequate copper ion but in effect these ions have very limited bacterial or viral disinfection qualities. You would have to change the water frequently to constantly freshen the copper ion.

It works great in pools because the objective is to control algae. However, it is always used in conjunction with a more common disinfectant. Other common uses are in foot baths and some agricultural practices. It can be used to clean reservoirs of algae but is not used as a primary disinfectant.

http://www.globalspec.com/events/siteRegistration?eventId=102&forcetok=1&GoToUrl=http%3A%2F%2Fwww%2Eglobalspec%2Ecom%2Fevents%2Feventregister%3Feventid%3D102%26evtsrc%3DIntlInvite%255FWQWR bioramani