Waste Water & Sewage Treatment System, onboard

I was cruising thru a June issue of Popular Science and ran across an award that had been given to this potential onboard sewage treatment device. I thought it definitely deserved some discussion on these forums.

"What if we could eliminate sewage? The ZLD virtually does just that! It takes the sewage (solids and liquids), grinds them up and homogenizes the solids in the liquid.

The ZLD then takes that liquid (that looks like chocolate milk) and pressurizes it and sprays this liquid into the hot exhaust gas of the engine. The hot engine gas vaporizes the liquid, and kills the bacteria and basically eliminates the sewage with no odor no liquid or no sludge to handle."

I went looking for a website and found this,
Zero Liquid Discharge (ZLD) Sewage Elimination System

 

I find it hard to believe that spraying **** on a hot exhaust doesn't stink. It would be interesting to see it in person though.

 

I remember a dog kennel where they regularly burned lots of dog-doo

and newspapers in 55 gal steel drums. Didn't stink, or at least not like what might be expected.

I believe the molecules that make **** stink are pretty easily broken down by heat. Pretty easily broken down by just about anything, fortunately.

I've seen references to camp latrine holes being doused with kerosene and lit in the military.

Biggest problem might be convincing your mechanic to go anywhere near it, no matter what the brochure says. Plan on doing your own maintenance.


And how would you assure the local authorities that:

1)The system actually does what it claims.

2)You are only discharging sewage fluid when the engine is running hard enough to produce enough hot exhaust.(does the system only discharge amounts of fluid based on temp/amount of exhaust? does motor need to be running hard to produce enough exhaust? I could see a lot of High-Sewage-Production/Non-Hard-Motor-Running situations in marinas or anchored for a few days where you wouldn't have a good opportunity to rev up the engine.)

3)That your discharge doesn't also contain pollutants that aren't broken down into harmless components by simply spraying them into exhaust. (this one IS sort an illogical red-herring, because having such a system in no way affects simply tossing pollutants over the side, but try explaining it that way to your local authorities).


What is the ball-park price for the system?

 

Squid,

Assuming it works as advertised I would imagine it will qualify as a USCG type I or II MSD system. Assuming it gets that approval it will then be usable just like those are today. This is just another way to achieve the same result.

Of course without an approval it is a useless toy, since it would be illegal to use.

 

I have a direct raw water cooling system on my exhaust. So I wonder if I can convince the authorities that, if I tip my poo overboard it will get sucked up into the cooling intake and go through the exhaust. :idea:

 

Do you fellows bother to read his site?

The technology has been certified by the U.S. Coast Guard in association with the U.S. EPA for shipboard use.
http://thezld.com/index.php/project-profiles

 

According to this:
http://thezld.com/index.php/about-the-zld/press/sail-magazine-july-2001
As soon as the microprocessor determines the exhaust gas has enough energy to vaporize the waste, it is fed into the engines exhaust pipe header or manifold through injectors. Encountering gases that are between 900°F and 1,000°F, the wastewater flashes to steam and the tiny particles of organic waste dry out and combust.

According to Nassef, who holds an MS in environmental engineering from the University of Oklahoma, all that remains afterward is harmless mineral ash about the diameter of dust, which is blown out with the exhaust. "You don't see anything different coming out of the pipe from what you see when a normal engine is running,' he claims.

 

This is 1960 motor home tech, many RV's had a system factory installed to vaporize the sewage tank contents while driving down the highway.

The systems were considered a failure as the maint requirements were too high.

A simple tank and 3 inch hose at a dump station or RV site was far less work.

 

FastFred, I've never heard of RV systems, what were the

maint requirements?


And, No, I didn't see the USGC approved bit, my bad.

Seems like the site is sort of short on details. I'd recommend they post at least 20 hi-res photos of one being installed on their target market type of boat.

 

First off let me clarify that I feel some responsibility to defend the item as I brought it up on the forums, and there appears to be a number of naysayers....but that is what the forum discussions is all about, particularly if there are informed replies.

Fred, is it possible that these RV units were quickly abandoned with the advent of the newer exhaust emissions controls as noted by another voice:
"I think the advent of catalytic converters and oxygen feedback systems on modern RV engines made their system unworkable due to oxygen starvation in the exhaust stream."

I don't see a lot of maintainence requirements in this diagram?
http://www.thezld.com/index.php/about-the-zld/press/sail-magazine-july-2001

 

ok now go and check how often your egt is over 900f

 

The USCG and the EPA may approve a system that treats sewage even though it stinks.

 

Note that that figure of 900-1000F is suggesting that the 'waste water flashes to steam upon encountering these sort of temps'. I'm sure it would also flash to steam at a considerable lower temp.


I looked here at some exhaust temps before and after turbo as many boating diesels use turbos, and I'm sure you don't want to inject anything before the turbo ....shitty or not
http://www.dieselpowermag.com/features/0607dp_exhaust_gas_temperature_basics/chevy_duramax_ford_power_stroke.html

 

Here is another informed reply from Trawlers & Trawlering

http://lists.samurai.com/pipermail/trawlers-and-trawlering/2011-May/157205.html

"Here we go again...this idea re-surfaces about every 10 years. It was
first tried in RVs about 30 years ago...and it actually seemed to work
pretty well....at least till the animal fats in waste began clogging up
catalytic converters and mufflers. There was also one more minor
problem: unbearable odor that gassed everyone in vehicles up to a
quarter mile behind an RV equipped with this system. So...it didn't last
long.

Several other would-be inventors have tried to make it work in RVs with
no better success...but the first--the ONLY--attempt to put on a boat
was about 15 years ago. Some Europeans put one on a muscle boat...it
worked, they put it on the market for a couple thousand bucks. What THEY
overlooked was, very few boats except muscle boats have dry
exhausts...and wet exhausts don't hot enough to incinerate anything.
Plus, there was still that pesky odor problem and those darned animals
fats. It was a short-lived venture.

Now, here we go again... This guy CLAIMS to have solved the odor
problem, but doesn't address the animal fats (it takes some time and/or
some VERY heavy toilet use for those build up enough to start to cause
problems, so he may not even be aware of it yet). So while it may work
on a RV, it still wouldn't work on most boats because most boats have
wet exhausts. However, I see on his website http://www.thezld.com/ that
he's had it "certified" by the CG and the EPA, but he doesn't say WHAT
he's had it certified as (plus, the EPA doesn't certify anything)...I
don't THINK it's as a Type I or II, but I'm gonna call him in the
morning to find out"....Peggie Hall