Hi Scott,

from the Janicki website the S200 machine processes 50,000 liters/day and produces 1-2 tonnes per day of ash. Because this is a combustion process there is no organic matter (carbon) left, so no N. The P and K will mostly be retained in the ash, which will hold value as a fertiliser.

cheers
Dean

Dear Kevin,
Thanks for returning to this thread and sparking such a lively discussion!

It would indeed be very interesting to know how this machine is working out in Dakar, and how they get around this issue of thickening/dewatering the fecal sludge before it can be processed in the omni-processor. I will send some e-mails in the background to alert the Janicki staff to this thread in case they haven't seen it yet.

Dean: the fecal sludge that is used as a feed to the omni-processor is not just from pit latrines but also from septic tanks (if I understand correctly). Even if flush water for the toilets was minimised the fecal sludge would still be rather liquidy in any case, as it gets pumped out from the septic tank. Also, when pumping fecal sludge from a pit latrine, water is often added to the pit to make it more easily pumpable. So just reducing toilet flush water would not make much any difference in this case.

In my role as moderator I have split off two conversations that started in this thread but that began to deviate from the topic of the omni-processor. This is not to say that the conversations are not important (quite the contrary) but it's just in order to keep things neat and tidy here on the forum.

Therefore, you now find the posts about the AlasCan system here:
forum.susana.org/component/kunena/205-ve...merly-alascan-system
(note it's also been discussed under its more recent name Human Endeavors here:
forum.susana.org/component/kunena/205-ve...in-future-costa-rica )

And the posts about the shower water recycling as started by Sjoerd are here:
forum.susana.org/component/kunena/40-gre...ling-eg-shower-water

If the people involved in those threads (Clint, Sjoerd, Kevin) prefer different thread titles or different sub-categories then please send me an e-mail about that (rather than telling me by forum post), thanks.

Regards,
Elisabeth

A couple of responses to posts over the last 24 hours.

First, while most wastewater and sludge treatment processes do replicate what nature does naturally, this is not the case with the Omni Processor. It relies on boiling off the liquid from the sludge, which is a very different concept to most treatment processes. As Pawan says, most septage has less than 3% solids and so the machine needs pre-treatment to dewater the sludge. Basically, you are then back to more conventional approaches to treatment and the thing can no longer be described as an Omni Processor

I am not entirely sure why septage quantities in Dakar are so high - the probable explanation is that pits and tanks do not drain because of the high water table but I do not have direct experience of this. I did some work early last year on a treatment plant in Myanmar which had similar problems because the water table was high and most of the 'septage' included water that could not drain away, probably with some that was infiltrating. I very much doubt if the problem is that people are using too much water when flushing toilets. I would expect most toilets in Dakar to be either direct drop pits or pour flush but others will know more about this than me.

The bottom line is surely that the Omni Processor is not an appropriate technology for sludge dewatering

Dear Elisabeth:
I have never heard anything about where the NPK goes. Do you have informationa about that?
best wishes
Scott

Dean Kevin
As per one paper of Strauss, 1996, Total solids in septage in tropical countries are less than 3 %. Therefore 10 % TS is not expected. In India it is taken as 2% TS only.
The calculation of energy balance from the Omini processor system should be explained by Janicki. It does not appear feasible to adopt the system due to high opex.

pawan

Kevin, keeping it simple, perhaps the residents of Dakar are using too much water in their flush? Could 10% solids be seen to be a reasonable and achievable aspiration...reducing unnecessary water consumption ten fold. Not that the concept behind the Janicki Omni Processor meets my approval, ash comes second to organic matter in the sustainabilty stakes.

cheers
Dean

For some reason, I did not complete the uploading of my first post today so I am resending.

In essence, I am answering my own question of a few days ago. I have now found a powerpoint presentation by Peter Janicki, the man behind the Janicki Omni Processor, which contains calculations that confirm my conclusion that the system is dependent on an external power source if the solids content of the incoming sludge is less than 10% - probably less than around 15% if efficiency losses through the system are taken into account. For solids contents less than this, the system starts to become very expensive to run because it depends on converting water into steam, which requires upwards of 700kWh per cubic metre. Most of this must come from external sources if the solids content of the septage is low.

So, regardless of the complexity, which is certainly a big issue, the maths shows that the system is not self-sufficient for septage such as that in Dakar, where the average solids content of septage is less than 1%. The options are either to import power or to pretreat the septage to produce a sludge with a solids content of at least 15%. both responses mean that the machine can no longer be viewed as an Omni Processor. So, yes there is an element of KISS about the whole thing but the main point that I would take from all this is the absolute need to do some simple sums before embarking on a project that costs millions and perhaps diverts much needed resources away from other initiatives.

On the role of the private sector, all that I would say is that we must remember the need to think in terms of complete sanitation system and the historic evidence is that the public sector has played a major role in dealing with aspects of the complete sanitation service chain that have public good characteristics - particularly treatment.

Why do we have such a hard time remembering the KISS rule, Keep It Simple Stupid? This system is not simple. Hoping and praying that a developing country has the expertise and the parts on hand to fix the break downs is ludicrous. If the money that is used to build and transport the device is instead used to educate and build small easy to fix and maintain systems (example UDDT) more people would be helped. We have all seen the relics of past good intentions that are scattered throughout the globe.
Sanitizing feces is not rocket science. Systems that work can be easily taught to the local populations. Education and buy in is crucial.

Hello everyone

I am returning to this topic after almost a year as I have been looking at the Omni Processor in the context that I am writing on faecal sludge and septage treatment. There is now more information on the internet about how the system work which is helpful in making an assessment. I have been doing some calculations on the energy input and energy output.

In essence, the machine heats water to the point at which it becomes steam. This explains why the water is drinkable. Lets assume that the water starts at 30 degrees CentigraTde. Energy is required to heat it to 100 degrees centigrade and then vaporize it.

The energy required to heat water is 4.186 Joules per gm per degree C
Based on this figure, 293kJ are required to heat 1 kg of water to 100 degrees centigrade
The energy required for vaporization is 2260 joules.gm or 2260kJ/kg
Thus, the total energy required per kg pf water is 293 + 2260 = 2553kJ
The energy required for one cubic metre will be 1000 times this or 2553mJ

Muspratt and others have assessed the energy that can be extracted from dried faecal sludge at about 17.3mJ per kg of total solids

The Omni Processor is installed in Dakar, where the septage is very watery with an average of about 4kg of total solids per cubic metre (0.4%)

So the total solids extracted from one cubic metre of water will be about 4 x 17.3 or 69.2mJ

This is only 2.7% of the energy required to vaporise the water

I am struggling to understand how the system can possibly work without substantial external energy inputs. Am I missing something? Can anyone enlighten me on this?

Kevin

I endorse the viewpoint. I have myself seen new equipment lying rusting, as people here simply don't know how to operate it. I uphold that motto: Keep it simple.

F H Mughal

I am amazed at all of the first world solutions to developing country problems. Who maintains the equipment? Who pays for the equipment? Where will the people come from that will maintain the equipment. Where and who pays for the repair parts. We have all seen unusable equipment that was originally installed to accomplish a purpose but was abandoned when it broke. KISS, Keep It Simple Stupid. There are many low tech solutions to accomplish the same thing. A UDDT will purify the excrement and provide fertilizer and soil conditioner.

Dear Pawan and all

Here is a slightly belated response to Pawan's last contribution. It is interesting that there is an initiative in Warangal. Several years ago, I was part of the consultants team for the Andhra Pradesh Urban Services for the Poor (APUSP) project and Warangal was one of the project towns. At that time, there was a pilot initiative in Warangal to test the constructed wetland option for wastewater treatment. From what I remember, the wetland had a free water surface rather than the more normal arrangement of having the water level below the level of the gravel bed. When I looked at it, my impression was that it needed some work to clarify parameters if it was to be of any real use for testing the constructed wetland approach. Not directly relevant to FSM but it shows that there were efforts to explore new ideas in Warangal.

Now on to my main point. Pawan's observation about actual septage quantities being less than design quantities is consistent with findings from elsewhere. We reached the same conclusions in Indonesia, where people often go for years without emptying pits. The figures quoted in WSUP publications regarding the number of pits emptied by the 'Dream Tean' in Kanyama, Lusaka lead to the same conclusion, the rate at which pits emptied shows that the average emptying interval is much greater than the 2 - 3 days commonly assumed. Even in the Philippines, where there have been serious attempts to introduce scheduled emptying, loads delivered to septage treatment plants have been less than assumed in design. Even in the United States, I came across a reference to the number of septic tanks emptied each year in Florida, which was much less than might be expected on the number of on-site sanitation facilities and a 3 - 5 year emptying cycle. I am putting together some notes on to provide input to a possible book on aspects of septage treatment. The other issue for design is the strength of the septage - the available information, which unfortunately is quite limited, suggests that the strength is often lower than the typical design assumption of 5000mg/l BOD.

These are important issues, which arguably should be receiving as much research attention as efforts to develop completely new technologies. It would be good to hear from others on efforts to obtain basic information on septage quantity and strength for design purposes.