Brainstorm black water waste idea

[Davydd]

I learned about the details of my custom 144 WB Sprinter being built by ARV. I could have put a composting toilet or a cassette toilet in with ease because the toilet is aft of the back axle and the waste tanks are forward of the back axle, but I have opted for a macerating toilet known as an up flush toilet mainly put in boats. So, I’m independent of needing a black tank to gravity dump below the toilet as the waste has to be pumped over the back axle. I will then have 24 gallon black tank and a 24 gallon grey tank. My current extended van has an 18 gallon black tank and 26 gallon grey tank so I am getting more capacity in a shorter van. One other feature, and Avanti will like this, is there will be a valve to combine the black and grey tanks for a total of 48 gallons of combined waste if desired (choice if necessary.) Subsequently the waste will still be dumped via a macerator. My fresh water tank will be 38 gallons compared to my current 40 gallon tank. It all is pretty much balanced out and more than what I have now so I can maintain my 6 year historic mode of only having to go to a dump station about every two weeks on the road. That means I can boondock without worry and quite frankly we will seek a campground periodically just to attend to tasks such as laundry and replenishment if not for site convenience or parks.

I think I am maintaining my goal in downsizing from 24 ft to 19 ft Sprinter in Mies - less is more. Bigger bathroom, more storage and no compromise on features. I am sacrificing my electrically operated articulating beds I conceived and designed in Alvar which has been a popular feature in ARV vans and picked up by others. BTW, my take possession date is mid-April. It has been a two year venture.

[GeorgeRa]

Originally Posted by Davydd

I learned about the details of my custom 144 WB Sprinter being built by ARV. I could have put a composting toilet or a cassette toilet in with ease because the toilet is aft of the back axle and the waste tanks are forward of the back axle, but I have opted for a macerating toilet known as an up flush toilet mainly put in boats. So, I’m independent of needing a black tank to gravity dump below the toilet as the waste has to be pumped over the back axle. I will then have 24 gallon black tank and a 24 gallon grey tank. My current extended van has an 18 gallon black tank and 26 gallon grey tank so I am getting more capacity in a shorter van. One other feature, and Avanti will like this, is there will be a valve to combine the black and grey tanks for a total of 48 gallons of combined waste if desired (choice if necessary.) Subsequently the waste will still be dumped via a macerator. My fresh water tank will be 38 gallons compared to my current 40 gallon tank. It all is pretty much balanced out and more than what I have now so I can maintain my 6 year historic mode of only having to go to a dump station about every two weeks on the road. That means I can boondock without worry and quite frankly we will seek a campground periodically just to attend to tasks such as laundry and replenishment if not for site convenience or parks.

I think I am maintaining my goal in downsizing from 24 ft to 19 ft Sprinter in Mies - less is more. Bigger bathroom, more storage and no compromise on features. I am sacrificing my electrically operated articulating beds I conceived and designed in Alvar which has been a popular feature in ARV vans and picked up by others. BTW, my take possession date is mid-April. It has been a two year venture.

When I was in the design phase I considered macerator toilet with silent centrifugal pump instead of positive displacement impeller pump, ended with cassette. Most could be quiet today, I don’t know.

[Davydd]

Originally Posted by GeorgeRa

When I was in the design phase I considered macerator toilet with silent centrifugal pump instead of positive displacement impeller pump, ended with cassette. Most could be quiet today, I don’t know.

I have no idea what the sound would be. It could be concerning at night but then our habit is we don't flush while peeing when sleeping to dispel any flushing sound and conserve water.

Gravity Flushing toilets have to be designed over the black tank which restricts where you place them in a van and could thus restrict the tank size.

Cassette toilets are usually dependent on an outside wall or open door to pull the cassette. I could have put a cassette toilet in and accessed the cassette by opening the back door but that would limit me to 5 gallons instead of 24 gallons. You still have to deal with and dump grey water.

Composting toilets can be placed anywhere but they need attending to with mulch preparation and carrying outside a van. They really aren't composting toilets as it seems comments about them have to be attended to by carrying a pee bucket every few days and I've read tending to waste can occur less than the two weeks I anticipate. You still have to deal with and dump grey water.

With a macerating toilet I designed it where I needed it for an optimum layout and for a larger bathroom than normal and the bonus was I could get a bigger black tank in an optimum location independent of the toilet. As mentioned our historic dump interval is two weeks with an 18 gallon gravity black tank. With a 24 gallon black tank coupled with a valve distribution with a 24 gallon grey tank I probably can anticipate three weeks or maybe more.

Believe me macerating with a closed in hose at both ends from a black tank is more sanitary than any other method and can be done just about anywhere you can dump a cassette other than the hose length limitation. Grey water is done at the same time in conjunction with dumping the black water tank. I like to follow up with grey water to flush out the macerator and hose.

[GeorgeRa]

Originally Posted by Davydd

I have no idea what the sound would be. It could be concerning at night but then our habit is we don't flush while peeing when sleeping to dispel any flushing sound and conserve water.
Gravity Flushing toilets have to be designed over the black tank which restricts where you place them in a van and could thus restrict the tank size.
Cassette toilets are usually dependent on an outside wall or open door to pull the cassette. I could have put a cassette toilet in and accessed the cassette by opening the back door but that would limit me to 5 gallons instead of 24 gallons. You still have to deal with and dump grey water.
Composting toilets can be placed anywhere but they need attending to with mulch preparation and carrying outside a van. They really aren't composting toilets as it seems comments about them have to be attended to by carrying a pee bucket every few days and I've read tending to waste can occur less than the two weeks I anticipate. You still have to deal with and dump grey water.
With a macerating toilet I designed it where I needed it for an optimum layout and for a larger bathroom than normal and the bonus was I could get a bigger black tank in an optimum location independent of the toilet. As mentioned our historic dump interval is two weeks with an 18 gallon gravity black tank. With a 24 gallon black tank coupled with a valve distribution with a 24 gallon grey tank I probably can anticipate three weeks or maybe more.
Believe me macerating with a closed in hose at both ends from a black tank is more sanitary than any other method and can be done just about anywhere you can dump a cassette other than the hose length limitation. Grey water is done at the same time in conjunction with dumping the black water tank. I like to follow up with grey water to flush out the macerator and hose.

Very good summary. 48gal under 144” WB is very good. I have total of 12gal fresh + 14gal grey + 4 gal hot Isotemp. In total 30gal of these tanks pretty much filled underfloor space without road clearance reduction in fulfilment of my off-road objective.

I still have my spare tire in factory space; it could be replaced with 21gal tank which could be another option for standard gravity drain toilet. https://agileoffroad.com/product/tir...tank-sprinter/

[Davydd]

Originally Posted by GeorgeRa

Very good summary. 48gal under 144” WB is very good. I have total of 12gal fresh + 14gal grey + 4 gal hot Isotemp. In total 30gal of these tanks pretty much filled underfloor space without road clearance reduction in fulfilment of my off-road objective.

I still have my spare tire in factory space; it could be replaced with 21gal tank which could be another option for standard gravity drain toilet. https://agileoffroad.com/product/tir...tank-sprinter/

They said that is a fresh water tank which fits where a spare tire goes. If it can be used for a gravity black tank then the the toilet would have go above it behind the rear axle and toward the center of the van because the tank is between the frame rails. You would have to modify it for the toilet to gravity dump into it and then you would have to have a 3" outlet to dump. The dumping would have to be somewhere under the back bumper and not the sides because of the frame rails and you could not couple it with grey water dumping which obviously has to be forward of the back axle where the only space left for tanks is. So you would need two separate outlets to dump which is not a practical solution. Dumping behind the back bumper is an iffy condition in a 170" WB Sprinter as they bottom out severely in my experience and I don't know if you could get the clearance. Points out why I need a macerating upflush toilet to get over the back axle.

[Nic7320]

Originally Posted by MarkS

I can't imagine the exhaust getting hot enough to incinerate. And, I'm guessing it would take a cross country trip to generate enough exhaust heat to evaporate a waste tank of liquid.

Most of the energy in fossil fuel vehicles goes out the radiator and tailpipe due to thermodynamic inefficiency, sometimes as much as 80%. You're powered by lots of little explosions that create pressure on the pistons to do work, but a lot more energy goes into heat.

https://rentar.com/efficient-engines...on-efficiency/

So for every $100 of gas you buy, you burn up at least $50.00 to $80.00 making waste heat you have no use for.

Some of this heat goes out the radiator, a device designed just to get rid of excess energy, and some goes out the exhaust system.

From https://mechanicbase.com/engine/how-...aust-pipe-get/

"While the average temperature for the exhaust is 300 to 500 degrees or 600 to 930 Fahrenheit, you can still experience temperatures as high as 1200 degrees or 2200 Fahrenheit whenever you have been driving really hard."

So if you can find a way to use some of this wasted energy for something useful... go for it.

[Bert M]

Originally Posted by Nic7320

Most of the energy in fossil fuel vehicles goes out the radiator and tailpipe due to thermodynamic inefficiency, sometimes as much as 80%. You're powered by lots of little explosions that create pressure on the pistons to do work, but a lot more energy goes into heat.

https://rentar.com/efficient-engines...on-efficiency/

So for every $100 of gas you buy, you burn up at least $50.00 to $80.00 making waste heat you have no use for.

Some of this heat goes out the radiator, a device designed just to get rid of excess energy, and some goes out the exhaust system.

From https://mechanicbase.com/engine/how-...aust-pipe-get/

"While the average temperature for the exhaust is 300 to 500 degrees or 600 to 930 Fahrenheit, you can still experience temperatures as high as 1200 degrees or 2200 Fahrenheit whenever you have been driving really hard."

So if you can find a way to use some of this wasted energy for something useful... go for it.

Thanks for all the discussion and ideas. My conclusion is evaporating liquid or incinerating waste using exhaust could work but (outside of putting it directly into the exhaust) no one has tried it. Maybe it wouldn't work, but maybe it would. Just trying to think outside the box and add another way to the already many options of disposing waste. That there are so many ways tells you there is not a one-size-fits-all for getting rid of our stinky stuff and there is room for improvement.

[InterBlog]

Originally Posted by MarkS

I can't imagine the exhaust getting hot enough to incinerate. And, I'm guessing it would take a cross country trip to generate enough exhaust heat to evaporate a waste tank of liquid.

It doesn't need to incinerate. Just evaporate. And yes, it could be designed to do that via an exchanger.

If designed properly and coupled with urine diversion, it could have real potential.

Kudos to the OP for unearthing a concept that I had not heard about in 6.5 years of off-grid forum-ing.

[GeorgeRa]

Originally Posted by InterBlog

It doesn't need to incinerate. Just evaporate. And yes, it could be designed to do that via an exchanger.

If designed properly and coupled with urine diversion, it could have real potential.

Kudos to the OP for unearthing a concept that I had not heard about in 6.5 years of off-grid forum-ing.

To get an approval for staying behind odor from NHTSA/EPA a special diet could be required.

[Nic7320]

Originally Posted by Bert M

... My conclusion is evaporating liquid or incinerating waste using exhaust could work but (outside of putting it directly into the exhaust) no one has tried it.

I wouldn't consider injecting it into the exhaust for several reasons,
1: you could create an exhaust leak
2: you don't mess with anything emissions related for Smog Testing.
3: DMV regulations say you can't eject anything from your vehicle, unless it's clean water or chicken feathers (yeah, someone got an exemption put into law).

California VC 23114.
(a) Except as provided in Subpart I (commencing with Section 393.100) of Title 49 of the Code of Federal Regulations related to hay and straw, a vehicle shall not be driven or moved on any highway unless the vehicle is so constructed, covered, or loaded as to prevent any of its contents or load other than clear water or feathers from live birds from dropping, sifting, leaking, blowing, spilling, or otherwise escaping from the vehicle.

But it would be simple enough to wrap the engine's exhaust pipe with a long length of copper tubing and inject the liquids into that. Just as long as there are no solids ejected. It's just another exhaust pipe, harvesting heat from your main exhaust pipe.

But you probably won't make many friends going down the road, aside from the occasional dairy farmer or cattle rancher. They're kind of used to that smell.

[Nic7320]

"While the average temperature for the exhaust is 300 to 500 degrees or 600 to 930 Fahrenheit, you can still experience temperatures as high as 1200 degrees or 2200 Fahrenheit whenever you have been driving really hard."

Years ago, I saw this first hand, when I pulled about a 8500 pound 27' boat over the Cuesta grade between San Luis Obispo and Paso Robles with a camper van. I pulled the engine 'dog house' cover off, and loosened the distributor, thinking I could advance the timing as necessary to gain some more power up the hill.

I made it, but by the time I reached the top of the hill, I could barely keep my toe on the accelerator pedal because the exhaust manifold was right next to it and glowing cherry red. I was also sweating buckets and the cab temp was probably over 140 degrees F.

Oh, I did pass a VW van at the top. He could barely get out of his own way.

Hauling a big boat up that grade wasn't a good idea at all. Any of it. Next time the boat went north, I took highway 1 to 41 and then back to 101. It's is a much easier hill and there's lots of places to pull off if needed. And now (since 2001 at least) it's required for all wide loads.

BTW, this rig had just a portapotty in it. It was not an official class B, but not bad as an RV. (just saying this to stay on topic)

[Boxster1971]

Originally Posted by mloganusda

Remember it well. Your black water, including solids, was metered into your exhaust pipe to be incinerated out the tail pipe. I looked into this in 1977 as I had a small MH in California at the time.

MLogan
Smyrna, TN

The system was known as “Thermasan”

Here is link to the owners manual
http://www.bdub.net/manuals/Thermasan-OwnersManual.pdf

. . . and the patent document
https://www.freepatentsonline.com/3731490.pdf

. . . this page has photos of the Thermasan system
http://www.gmcmhphotos.com/photos/g3...hopefully.html

They were an option on the GMC Motorhomes and FMC Motor Coaches from the 70’s.

https://www.hagerty.com/media/market...c-motor-coach/

Enjoy

[Bert M]

Originally Posted by Boxster1971

The system was known as “Thermasan”

Here is link to the owners manual
http://www.bdub.net/manuals/Thermasan-OwnersManual.pdf

. . . and the patent document
https://www.freepatentsonline.com/3731490.pdf

. . . this page has photos of the Thermasan system
http://www.gmcmhphotos.com/photos/g3...hopefully.html

They were an option on the GMC Motorhomes and FMC Motor Coaches from the 70’s.

https://www.hagerty.com/media/market...c-motor-coach/

Enjoy

Thanks for posting! The Owner's Manual for the Thermasan is historical and hilarious! A few of my favorite quotes from the manual:

- Recreational vehicle owners with Thermasan units avoid inappropriate temptations between dump stations.

- Generally you may figure that you must operate the system one hour to burn the waste created in one day by each person in your party.

- Question: Will other people on the highway know that my Thermasan unit is operating? Answer: No. Your exhaust emission will be free of visible steam and odor.

- Question: Are there any materials that should not be put in my holding tank or should not be mixed with the waste? Answer: Do not put any highly combustible materials such as kerosene, alcohol, or gasoline in your holding tank.

I did find a post from an engineer on the Thermasan unit. He said it did smell, but no more than many diesels.