Preventing odors

I am retrofitting a toilet in an RV (used as guest house). We want to store the waste in the tank as normal (the old toilet broke, so I built a wood one). What is the best thing to sprinkle on the waste to eliminate odor?

thanks.

For me the answer is a fairly fine sawdust but for you it can be almost any plant matter that is fine enough to form an odour barrier without excessive bulk. Rather than use the old RV tank I would suggest a 5 gal pail sawdust toilet. Easy to handle, cheap to come by and works well in the whole composting cycle. Read up on it at http://www.jenkinspublishing.com/messages/ .

I second the plant matter., about three or four times as much plant matter as solid deposits, and using a smaller container that you can easily take outside and compost elsewhere. Your biggest problem will be flies and gnats, especially in the summer. One day you will wake up and the ceiling will be lined with flies. Hang a fly strip in the bathroom and see how many gnats it catches. I have never managed to stop them. So being able to take it away, rinse out the container, get any laid eggs out of there is a big help. The eggs show up within a week, they are fast! They can squeeze through super tiny spaces to get at the contents of that toilet.

Mowed weeds in big amounts works pretty well in the meantime. You can include different herbs like pineapple sage, eucalyptus leaves, sage, mint, catnip, etc.

It definitely needs to be vented to the outside. Sewer gases can be fatal, BTW.

Cristo in my experience sawdust toilets do not produce sewer gas or have odour or fly problems. If you are having these problems I believe a cover material change will correct them. I do however lack personal experience in any area other than central Canada so I am not 100 percent sure about the fly problem. From what I have read posted from other areas of the world though I believe this to be true as well.

Cover material needs to be a certain fineness to work properly. I did have one batch that was too coarse and required unusually excessive amounts to achieve an odour free state.

Kelly, it might be good if you give more detail on what you are wanting to do. By 'store' do you mean compost? Or store and then empty into the compost bin later? What kind of tank it is? (built in, or portable).

I agree that flies are an indication of not enough cover material, but also that climate is a big part of it. I'm not sure about putting strong anti-microbial herbs in a bucket system, but I guess it depends on quantity.

I'm using the built-in tank - a bucket would be almost inaccessible because the tank is above the axle. I plan to flush it out with water after a reasonable time. The main difference with the RV toilet is there is no flap to prevent odors, but it didn't even have a u-joint water-lock. sys Also, my system does not have water when you flush, but that was a very small amount anyway. The tank is flat, but has a water-tight seal at the outlet for later dumping.

thanks for answers

Well, you might research 'bokashi', which uses mainly lactic bacteria... sauerkraut juice, etc. ... to 'pickle' anything... even poop. I think it results in 'pickle' odor - might not attract flies. There are commercial cbokashi units sold that advertise they handle pet poo. Of course, I assume urine is not going into the toilet, but directly to where it belongs... fertilizing the biozome ;) (For us women, the old Nestle Quick Chocolate Powder plastic jar - large size ;) - is a very handy way to collect ;) - make brownies with the powder, or bury it as fertilizer, also :)

Kelly, it is incredibly hard to flush out an RV tank with liquid sludge in it, (that has been broken down by the additives that are necessary in a black water tank) let alone solids, paper that isn't broken down, sawdust and composting material. In fact, I can't imagine how it would even happen, unless I'm misunderstanding how big the outlet of the tank is. Composting toilet contents are shovelable, not floatable. You probably ought to try getting it out of there before it gets too full.

Wyatt, any sewage that is breaking down in that compost off-gasses, at the very least, methane and ammonia (and several more depending on what's in there) and those are toxic gases when they aren't vented to the outside. "Toxic" also includes risk of explosion, which includes methane. Cigarettes can set off methane. Lots of recreation areas that have been built over old dumps that are leaking methane have had flames shooting out from the ground when people sit there with cigarettes.

To be safe, because we don't know what conditions people get themselves into with these homemade composting toilets, and how many people are using them, and how often they are emptied, and how much carbon materials is added, we ought to assume it is not safe to be in an unvented location with the contents of those. Maybe they are fine in some situations, but it's serious enough to be safe rather than sorry

Gnats and flies at my location easily get past sawdust. The types of flies are location specific, I imagine. I've got the small hover flies under the pine trees, and they get into everything. Gnats can squeeze under even a cast iron lid. Summer is worst. Even Paul Wheaton's containers they roll away to somewhere else and put a clean container under there.

Rose, I haven't had any issues with herbs or aromatic leaves. It doesn't take much, and it's probably more psychological than practical

Cristo I expect you are right about the location specific flies but I don't agree with you about a sawdust toilet off gassing. Technically a sawdust toilet is not a composting toilet since the pail is just holding the material under the wrong conditions for composting. On this one I now have one year of personal everyday experience plus experience working around septic tanks and pump chambers. I know about methane bubbling out of sewage and I have either no noxious gases coming out of my sawdust toilet or the amounts are so minute that I can't detect them. Again, just my experience but I suspect that if you did have a problem with off gassing then a cover material change is needed.

I do however completely agree with you about the RV tank. Not doable as a hybrid. Either valve it and use like it is designed or switch to a 5 gal pail system. It will fit easily into the same space as an RV toilet.

Wyatt, yeah, I imagine many other people are reading these threads, so I try to make generalizations so many folks will be alerted to what could happen. You mention using a bucket, which is the smallest amount, it's the least likely to get anaerobic. If you take that bucket elsewhere, outside to compost, that would help having any methane build up indoors.

But other folks, with large tanks or wheelies in their basements or containers they seal up tight as a drum so they don't have to look at it or deal with it, it's not safe to have those nonvented containers in their basements with a gas water heater pilot light or a leaky seal that allows methane to escape up into the bathroom. I exchanged emails with a family in Canada where everything was frozen in winter, so all the containers had to be indoors, and in their basement. Methane buildup was really dangerous. Composting of any substance needs oxygen. Openings for oxygen allow methane to escape and there is your explosive situation.

We can't escape chemistry. Gardeners eventually run into it, (alkalinity and acidity) and so do compost toilet folks. Methane is an odorless, colorless gas, and it has to be there because that's part of the breaking down process of poop and urine, to put it bluntly. Ammonia is in all urine, and it's always present. Sawdust doesn't stop the methane or the ammonia. Sawdust is just carbon, mowed weeds are just carbon, they can only absorb so much liquid to try to stop it from being anaerobic sludge, and that's what we smell.

If you had a methane gas alarm near a composting toilet tank with months of new additions, it would go off. Just like when we install a wood burning stove and have to install a carbon monoxide alarm. That is also a colorless, odorless gas. Whole families have been found unconscious because their wood stoves were not properly sealed or vented. Some folks have passed out from carbon monoxide poisoning because they let their cars run in the closed garage and the carbon monoxide exhaust fumes get into the house. They had no clue what they were breathing because it was odorless.

Some people are tidy, others are not. Some people are responsible, others just want to poop and ignore it, so it's important to warn folks who think composting poop and urine is no big deal. As much as we all want to get back to nature, it is not as simple as it sounds. Municipal utilities happened because there are dangers involved. So when anyone reads a thread like this, I hope they will be forewarned that there is a complicated and scientific process that does happen, and we need to know what is going on and how to handle it

I also can't see how you could use an RV tank for a composting toilet system. Are you sure that you want to compost? If you want to use the tank you will need to add water, and that creates normal black water, not a compost system. Further, the reason that composting systems don't smell is because you cover the poo with cover material. You can't do that in a tank.

How are you planning on dealing with the sewerage/humanure once out of the tank?


"Rose, I haven't had any issues with herbs or aromatic leaves. It doesn't take much, and it's probably more psychological than practical"

Ah, nice.

I don't want to compost in the tank. I would be happy flushing it out immediately into a composting hole, but the tank works by holding water for a few days, then flushing it all at once - hence the need to control odors until the bi-weekly flushing.

Hmm, I have a limited knowledge of RVs, but I'm a tad skeptical about attempting a flush-less system while using a system designed for flush toilets.....all that water from flushing is supposed to help the solids move through the pipes so the tank can be emptied, no? If you sprinkle cover material, won't that make the sewage very think and difficult to empty?

Kelly, I have been having flashbacks on all the awful hours I spent with an RV tank under normal circumstances. It was floating sludge of deposits, lots of water, paper and the bacterial eating liquid that goes in it so the solids will break down into real sludge, and the theory is that because the tank is holding "liquid" it will float out of there, and so I thought. I hooked on that hose, and put the other end into septic tank opening for it, heard a lot of rushing stuff and thought, great, there it goes.

But what was actually happening was that the solids were settling on the bottom of the tank and the liquid was floating above it. It wasn't completely emptying. Using a flashlight I looked down through the toilet opening and saw a foot deep layer of nothing but solids and paper. They weren't floating, they weren't breaking down. It was a monumental task to get that stuff out of there, I had high powered hoses and I was kicking the bottom of the tank from underneath to get the contents to break into smaller bits. I must have used 1,000 gallons of water, the stuff was so stubborn and wouldn't move.

That was the event that got me using composting toilets in the first place 20 years ago. I got the kind that has the tank in the room, and you sit up high over it. That evolved into a bucket style inside the tank you sit on so I could take it out and compost it outside, so muss, no fuss, no insects. Then that blasted black water tank was never to be struggled with again. If you want to eventually sell the RV, just save the toilet, put it in your garage, temporarily seal the blank water tank opening, and keep the composting unit right where you cant get to it.

Otherwise, I feel for ya when it comes time to empty that black water tank.

Kelly, and if you don't believe me, go look on the internet all the trouble people are having with RV tanks with normal contents. They talk about adding bottles of Joy dish soap, I guess to try to make it slippery (I still don't understand that one, and it would screw up a septic tank). They are trying all kinds of stuff, that would destroy the ability of it to compost. None of that ever worked for me.

And BTW, even if you got the stuff to go out of there, I hope you are further composting it and using it in the landscape, rather than emptying it into a septic tank. Composting toilet carbons are not meant for a septic tank.

And if we were to get rid of the composting toilet contents into a city sewer system, and they start finding sawdust or big levels of carbon weeds in their system, it might even be considered illegal dumping. They can track where it comes out of a house line and starts going into their system. It's not what even their system is designed to handle.

Kelly Mitchell wrote:I don't want to compost in the tank. I would be happy flushing it out immediately into a composting hole, but the tank works by holding water for a few days, then flushing it all at once - hence the need to control odors until the bi-weekly flushing.

How are you proposing to compost what is essentially blackwater? I can't see what you are trying to do. I've used a portable RV toilet with no chemicals and little water, but it's still a liquid and solids mix that pours out and is not easy to compost. The smell was controlled by the slide between the toilet and the catchment bin. If you are using no water, then you can use sawdust or other cover material to eliminate smell, but I can't see how that can be done in a tank with a narrow inlet and outlet. You need access to the poo to cover it adequately.

I live in an RV. I use a Joe Jenkins/Humanure 20L bucket with sawdust that gets emptied every week or so into a compost bin or wheelie bin. I tend to separate the urine, because it makes the buckets lighter (I have a separate sawdust/pee only bucket). I would choose this system over a system that had added water/created blackwater any day of the week (emptying blackwater that's been stored would have to be one of the grosser human activities, as per Cristos' story).

The only way I can see what you are proposing working is if you rejig the tank to be used more like a 20L bucket or wheelie bin storage that gets dry emptied, but you can't use water to flush them, that creates problems for both composting and pathogen control.

A little vent stack works wonders. Obviously this requires some doing, but in essence is very simple - a 4" pvc pipe with a little 12v muffin fan.

We have a plywood box built to fit a 5 gallon bucket. Out the back is a 4" pvc pipe that takes a 90 degree bend up through the roof. There's a screen at the top of the pipe to prevent any flies.

I built a slab-wood outhouse and put in a chem. toilet in the trailer for 'emergenices.' Old people are staying there.

No vent installed in my present sawdust toilet, which replaced a flush system, and none is needed. Odour is a sign of improper covering which should be corrected anyways. If a good venting system was in place the cover might not be properly applied which would promote insect problems.

Wyatt and Vlad, what do you do about gnats if you don't have a vent they can get out?

kelly, you've probably run across this online about RV toilets, even the chem one have paper issues, and should only use single-ply paper. But that tends to make people use more. I never found the paper to dissolve the way they expected it to, so filling it with water just before emptying it more often floated most of it out of there.

Cristo I am in central Ontario Canada using sawdust as a cover material. Our area has lots of flies and it has been my experience being in the same house for 27 years that there are good and bad years for every pest in existence. One year it was ladybugs, last year was mice and this year it's wasps. I have not noticed an increase in any flies in the house since we switched to the sawdust toilet over a year ago. I have heard of people having fly problems but I wonder if it is not an unsuitable cover material or possibly bringing in the fly larvae on the cover material. My system has no vent and no traps, just good cover and

I have for ten years (S.E.UK) used an old plastic coal bucket with a lid(strong!) that is kept in a large laundry container dustbin shaped in the bathroom.the lower half of the container has the sawdust in it(free from a local furniture maker). The coal bucket sits on a plastic grid to keep the sawdust of it. The 'coal' bucket is put in the toilet,toilet used in the crouch position,best for most efficient bowel evacuation. The bucket when nearly full is emptied into the compost heap interleaved with the prunings from evergreen wall plants kept in the compartment beside. There is no smell in the bathroom or garden.the walnut sawdust was the best unfortunately they only have pine at present which is a bit dusty! Bedsit tenants who use the bathroom thought it was a laundry container until I explained.The fact that I am a mostly raw food vegan may partly account for the lack of any smell though I dont think so. The compost bin lower contents are removed after about a year after it fills up, somewhat sticky and loaded with worms and a miriad of other creatures.placed on the garden late winter, as new loads are added various fungi are sometimes growing. The heap is always warm which doesnt seem to discourage the worms though they dont like the addition of urine,wriggle furiously but dont seem to come to harm as a result. Sometimes mice take up residence no doubt to eat undigested seeds!but go when the compost is removed. A plastic nappy bucket could be used though the stonger old coal buckets are more secure,you wouldnt want one to break in transit! The compost bins are some distance from the house but would be o.k. close due to lack of any smell. We are lazy gardeners and self seeding New zealand beet leaves,rocket,coriander,fennel grow lush and plentiful,Resident hedgehog and frogs from two ponds I assume account for the abscence of slugs,the neighbours cats,which I am constantly at war with unfortunately keep birds away from dealing with snails but they dont do much damage. Chilli powder is the only mostly successful cat deterrent I have so far found.