Holding Tank Discharge Plumbing

[Ribbit]

To me the real issue with sewage systems/holding tanks isn't being addressed on boats. They aren't usually properly addressed on land either, for that matter.

I've been involved a fair bit with this (on land) as a friend has a company providing equipment to sort a lot of problems out.

No 1 issue, is problems created by anaerobic bacteria. Sludging, crusting (floating on top of the sludge), and the slime that anaerobic bacteria surround themselves with as a protective barrier. Plus the smell associated with the process of anaerobic bacteria making methane.

Now a boat doesn't have a septic tank, where treatment using anaerobic bacteria is split into two tanks (settlement tank and the next runoff tank) prior to dispersion through a soakaway or drain field. This system can work successfully for decades, until the anaerobic bacteria gum up every part of it (with the slime completely blocking even the drain field).

Now the speed with which an aerobic system can clean up a septic drainage system, is quite surprising. I have seen aerobic bacteria fully restore a septic system, including the drain field, in about 10 months. This was a system that had functioned without interference, for over 50 years, and then blocked up solid.

Perhaps the most pertinent aspect, is what happened to that first tank in the system, which bears a close relationship to a boat holding tank. It started off with such a heavy crust, floating on a thick treacle of sludge, the owner had even tried breaking it up with steel rods.

I got him to buy a heavy duty air pump (for long term reliability and the volume of air it could supply), run a hose from it to a piece of tube long enough to get to the bottom of the tank, and fit an air diffuser to it, for lots of fizzy little bubbles to be pumped into the tank. The aerobic bacteria will also attack the anaerobic bacteria, and treat their slime protection as another food source. It took a few weeks for that first tank to start circulating properly, with more and more oxygen content, but within a month, and plenty of extra flushes to get enough water in there to help dilute and assist (as an aside, reduced flush water in 'saving' water, is having a terrible effect on sewage systems everywhere), the inches thick crust (I wasn't going to get too close to look at it, but it seemed to be a bit over a foot thick) was gone, and in another couple of weeks, the contents were transparent, and a dipped sample looked like tap water. Within a year, the complete drain field was restored, as all the blocking slime was consumed by the aerobic bacteria. Associated smells had long disappeared too.

So that is why I would be interested in a small reliable airpump, with a diffuser to go into the bottom of the holding tank. I don't think there'd be much problem with wear and tear of fittings and hoses, with one (and vegetable oil as a lube, once it had done its work, they would eat to dispose of it too).

Frankly, if such a system was installed, as long as you could guarantee tank contents not being added to for a week, with the diffuser working constantly, I think you should be able to pump out quite safely, anywhere.

I have seen somebody drink the runoff from an aerobic system, but you wouldn't catch me doing it.

When I get a good look at the system my boat arrives with, I'll have to look a lot closer at this.

PS. The speed with which aerobic bacteria deals with 'stuff' used to be easily observed in practice. Unfortunately, thanks to 'Pooper Scoopers' this process isn't as easy to observe for most people any more.

[HopCar]

Ribbit FYI Groco sells the components to make a tank aeration system.
Thanks for that post.

[peghall]

Originally Posted by HopCar

Ribbit FYI Groco sells the components to make a tank aeration system.

Not just components, the Groco Sweettank is a complete holding tank aeration system. Groco Sweetank installation instructions

[Ribbit]

Thanks for the tips on Groco. Once I get au fait with the installed system, I'll know what to get.

[peghall]

Unless the the tank is at least 40 gal + or deeper than about 20", aeration is rarely necessary. Passive ventilation above the surface is enough to keep the tank aerobic if it's done right.

[valhalla360]

Originally Posted by Ribbit

To me the real issue with sewage systems/holding tanks isn't being addressed on boats. They aren't usually properly addressed on land either, for that matter.

I've been involved a fair bit with this (on land) as a friend has a company providing equipment to sort a lot of problems out.

No 1 issue, is problems created by anaerobic bacteria. Sludging, crusting (floating on top of the sludge), and the slime that anaerobic bacteria surround themselves with as a protective barrier. Plus the smell associated with the process of anaerobic bacteria making methane.

Now a boat doesn't have a septic tank, where treatment using anaerobic bacteria is split into two tanks (settlement tank and the next runoff tank) prior to dispersion through a soakaway or drain field. This system can work successfully for decades, until the anaerobic bacteria gum up every part of it (with the slime completely blocking even the drain field).

Now the speed with which an aerobic system can clean up a septic drainage system, is quite surprising. I have seen aerobic bacteria fully restore a septic system, including the drain field, in about 10 months. This was a system that had functioned without interference, for over 50 years, and then blocked up solid.

Perhaps the most pertinent aspect, is what happened to that first tank in the system, which bears a close relationship to a boat holding tank. It started off with such a heavy crust, floating on a thick treacle of sludge, the owner had even tried breaking it up with steel rods.

I got him to buy a heavy duty air pump (for long term reliability and the volume of air it could supply), run a hose from it to a piece of tube long enough to get to the bottom of the tank, and fit an air diffuser to it, for lots of fizzy little bubbles to be pumped into the tank. The aerobic bacteria will also attack the anaerobic bacteria, and treat their slime protection as another food source. It took a few weeks for that first tank to start circulating properly, with more and more oxygen content, but within a month, and plenty of extra flushes to get enough water in there to help dilute and assist (as an aside, reduced flush water in 'saving' water, is having a terrible effect on sewage systems everywhere), the inches thick crust (I wasn't going to get too close to look at it, but it seemed to be a bit over a foot thick) was gone, and in another couple of weeks, the contents were transparent, and a dipped sample looked like tap water. Within a year, the complete drain field was restored, as all the blocking slime was consumed by the aerobic bacteria. Associated smells had long disappeared too.

So that is why I would be interested in a small reliable airpump, with a diffuser to go into the bottom of the holding tank. I don't think there'd be much problem with wear and tear of fittings and hoses, with one (and vegetable oil as a lube, once it had done its work, they would eat to dispose of it too).

Frankly, if such a system was installed, as long as you could guarantee tank contents not being added to for a week, with the diffuser working constantly, I think you should be able to pump out quite safely, anywhere.

I have seen somebody drink the runoff from an aerobic system, but you wouldn't catch me doing it.

When I get a good look at the system my boat arrives with, I'll have to look a lot closer at this.

PS. The speed with which aerobic bacteria deals with 'stuff' used to be easily observed in practice. Unfortunately, thanks to 'Pooper Scoopers' this process isn't as easy to observe for most people any more.

A few misconceptions.
- Anaerobic works just fine in household septic systems and should never fail on a properly designed system. There is no buildup compared to aerobic decomposition. Totally unrelated to holding tanks which are more akin to sess pools (as in both need regular pumping out).
- If you want to try a cheap airation system (and yes, an non-airated holding tank will typically go anaerobic if there are more than a few inches of liquid and the boat is in a quiet harbor without a lot of sloshing action), a cheap aquarium air pump should do the trick if silcone seal it into a hole drilled in a spare inspection port.

Unless the vent is placed such that it directs odors to the cabin or cockpit, it's usually not worth the trouble as the vent dispates the odor as it is produced.

[peghall]

Now a boat doesn't have a septic tank, where treatment using anaerobic bacteria is split into two tanks (settlement tank and the next runoff tank) prior to dispersion through a soakaway or drain field. This system can work successfully for decades, until the anaerobic bacteria gum up every part of it (with the slime completely blocking even the drain field).

Apparently you're unfamiliar with Type II MSDs (USCG certified treatment devices for vessels over 65' LOA,) which although are not septic systems, work pretty much as you describe, except the first tank is not a "settlement" tank, but where waste is broken down aerobically, then filtered into the second tank where it's chemically treated to kill bacteria and virii before trickling overboard.

As for aerobically managing holding tanks, I began preaching that in the late '80s...my own company introduced the first bio-active (live bacteria) tank product (originally "Peal Products K.O.," became "Raritan K.O." when I sold our product line to them in 1999)...and we were the first to promote shorter, straighter, larger diameter vent lines to provide the air exchange needed to keep most tanks aerobic and therefore odor-free. My third book that deals with all this just became available in print this week and will be available as a Kindle within a week or two.

an non-airated holding tank will typically go anaerobic if there are more than a few inches of liquid and the boat is in a quiet harbor without a lot of sloshing action),

Not true. Unless a tank is deeper than about 20", or is in a location that makes a short straight relatively horizontal vent line--somtimes two vents-- impossible (buried in a deep bilge, for instance), passive ventilation above the surface and an organic (iow, not formaldehyde or other lethal chemical) tank product used according to directions can keep it aerobic without the need for aeration.

[Cadence]

Would it be out of line to say I don't know **** about this?