What do you think of this compost bioreactor system?

It is not intended for human waste composting, but should work.

mb-soft.com/public3/globalzl.html

JKMakowka wrote: Biogas slurry is also not necessarily a better fertilizer as disinfected fecal sludge as most of the organic components are lost to the methane production and thus the "soil conditioning" properties of it are mostly lost.

That's excellent information. Contrary to popular belief, I am a JK fan.

Isn't biogas slurry also considered a danger, i.e., causing chronic botulism in cattle and wildlife such as birds? Biogas production selects gram-negative spore-formers (pathogenic clostridia) while killing their competition, leaving an imbalanced ecosystem. This issue seems overlooked in the AD industry poised for explosive growth.

I'd like to see priority placed on aerobic composting. This recent news talks about the HotRot system:
www.theguardian.com/sustainable-business...sustainable-solution

Here are two animated videos describing their modular system now in operation in NZ:

I have been studying a bit and now have a concept process that uses the following equipment:

Low water use marine toilet with macerator pump
Process container with hot water coil and venting
Hot water heater and hot water reservoir separate from drinking water
Controller to monitor heat, control valves, control hot water pump

I wanted to know how costly this would be to run, so I did a calculation. My target treatment heat was 70C for one hour. I did not include the cost to maintain the hot water heater at its temperature, which is an important missing piece of information. There is no attempt to address efficiency losses.

The processed human waste could then be composted or used in a biogas digestor, with the resulting resource used for fertilizing gardens on site.

Cost to Disinfect Human Waste Per Day by Heat Treatment

1.5 Waste per person per day (kg)
1.0 Persons using toilet
6.0 Flushes per day
1.0 Liters per flush
7.5 Kg waste per day

16.0 Starting temperature (C)
70.0 Hold temperature (C)
60.0 Hold time (minutes)

7.5 Process Kgs
1,000.0 Calories per Kg-degree
7,500.0 Calories per Process-degree
54.0 Change in Temperature (C)
405,000.0 Calories
4.2 Joules per calorie
1,694,520.0 Energy (joules)
360.0 joules per Watt-hour
4,707.0 Watt-hours
4.7 kW-hours
0.1 $/Kw-hour
$0.47 Cost per day ($USD)
$0.05 Hold Time Adjustment (10%)
$0.52 Heat Treatment Cost per Day Per Person

$15.60 per month per person. As a comparison, my current sewage bill is $37.62 per month for 2 persons.

This is not a sustainable method, but I wanted to show a conservative number for the cost of heat treating human waste.

Some ways to improve the efficiency would be to use a urinal for males, to reduce the flush water volume, to use a solar oven for heat and to use biogas rather than electricity.

Septic tanks here are, quite often, circular in shape, made of sulfate-resistant cement. This prolong the life of the structure. In rural areas, the septic tanks are connected with soakpits. The effluent from the soakpits diffuses in the subsoil. This is only done in the rural areas with sparse settlements and, where there is no sewerage system.

F H Mughal

Biogas production after heat disinfection will be a bit difficult and for sure require some outside source of the needed methanogenic bacteria.
What you could think of is direct "thermophilic" biogas production, which is quicker and somewhat pasteurizes the waste also.

Biogas slurry is also not necessarily a better fertilizer as disinfected fecal sludge as most of the organic components are lost to the methane production and thus the "soil conditioning" properties of it are mostly lost.

Edit: if you are working with a vacuum sewer: a while ago I was working on a concept of combining that with a ATAD (autothermophilic aerobic digestion) system, as the exhaust of the vacuum-pumps could be used to aerate the sludge. Never got anywhere near to testing it, but the concept seems feasible.

I found these documents to be very helpful:

esa.un.org/iys/docs/san_lib_docs/Compend...ys_and_Tech_2008.pdf

susana.org/lang-en/library?view=ccbktypeitem&type=2&id=1019

www-wds.worldbank.org/external/default/W...d/PDF/multi0page.pdf

Attached is an idea for a home or number of homes. A vacuum sewer system removes urine and fecal matter from the toilet, so the user does not have to deal with smell at all.

en.wikipedia.org/wiki/Vacuum_sewer

The waste builds up in a reservoir until a float switch activates a tube screw conveyor. The conveyor motor is a stepper motor, controlled to move waste through a heat exchanger which heats the waste and disinfects it. Temperature sensors indicate when the appropriate temperature and time have been achieved for each slug of waste.

The waste then is transferred to a biogas digester, producing biogas and spent liquid slurry as fertilizer.

The drawing is conceptual, I am sure there are better ways to connect the system components.

Hi Paul,

in Eastern Germany, off grid sanitation systems (or decentralised sanitation, as it is called there) are quite common. Technologies for small wastewater treatment plants and regulatory frameworks are well established now.

Here is a good website giving information on technologies, legal situation, control and monitoring, operation and maintenance. abwasser-dezentral.de

Unfortunately all in German, but you may get the main points with google translate: translate.google.com/translate?hl=&sl=de...tral.de%2F&sandbox=1

However, the systems there do moreless the same as municipal wastewater treatment plants do: treating wastewater and discharging it into water bodies. Thus many of your listed conditions would not be met.

But I also have to say that I am not aware of any existing system that would meet all your listed criteria. Probably you will need to rethink some of those.

Some issues I see with your criteria:
- What do the users want? Urine separation would require some change of the usual toilet use. Are the users ready for that?
- Costs: if a simple septic tank costs 10.000$ and a sewer connection 5000 $, it is probably quite unrealistic to expect that for 5'000 $ you can get a system doing all what you want, with that degree of automatisation etc.
- Pumping sludge to soil to be fertilised. If you mean a fertiliser use nearby or on the same land, this will only work if such a use is required/desired. As this is unlikely to be the case for all houses, the system would not be applicable as a generalised solution.

Best, Florian

Dear Christoph,

Sorry for hurting you with my harsh words. You know you are not part of this kind of SALES.
Maybe try it out by your self and pretend to be a possible consumer without your know-how and asking some supplier for "technical" small wwtp's (4-50 pe) for information.

Maybe we should have a customer driven system like this too : "Botch? No Thanks!
www.murks-nein-danke.de


All the Best
Detlef

Detlef,
I feel somewhat hurt by your words.

- Ask each dealer/supplier for a long reference list with full street address. If they are not willing to give complete list to you, they have to hide problems!

I don´t give name and address - I try to maintain privacy of my clients.

- do not visit costumer recommended by dealer/supplier, they are paid for each lie.

I only recommend some plants where I do have an agreement with the client that visitors are welcome....I don´t pay anything for that.

I understand what you meant, but I think the way of expression is very harsh.

All the best.
Christoph

As you are "still learning about this field", let me give you a more general guide to start with to find reliable ready made systems you are basically looking for:

- looking for most simple systems, regardless "technical" system solutions or "close to nature" systems solutions

- Have only limited trust in information provided by dealers/suppliers of this systems

- Ask each dealer/supplier for a long reference list with full street address. If they are not willing to give complete list to you, they have to hide problems! If not given you may asking "your" NSA a good reference list example is my own example: aqua-verde.de/page6.php

- collect YOUR OWN information by visiting a large number of former costumer of different suppliers and systems

- do not visit costumer recommended by dealer/supplier, they are paid for each lie.

Sounds not very happy, but it will keep you on a save path by generation your OWN experiences.

Again Good Luck with your search
Detlef

For that purpose, the Loowatt currently under development seems excellent.
www.loowatt.com/

I'm not sure I agree with use of biodegradable plastics, but in terms of user satisfaction it seems great, especially considering your stipulation No human contact with fecal matter is required.

You wouldn't have to include the biogas part of the Loowatt system if aerobic composting is the priority. I still wonder about the safety of anaerobic digestion given concerns about pathogenic clostridia in the finished waste. The developer of Loowatt, Virginia Gardiner, is on this forum, so perhaps she can chime in here.

Another option might be something like a Sun-Mar system (Centrex) with a pickup program.
www.sun-mar.com/prod_flush_cent3_acdc.html