Hi Dorothee

In the interest of keeping this thread dedicated to the main VUNA findings, I started a new topic called "Monitoring and Evaluation" and replied to you over there: forum.susana.org/forum/categories/142-up...oring-and-evaluation

Let's keep the conversation going!

Liz

Hello,

I have a few questions about the cost as I couldn't locate them in the documentation:

How much does the reactor cost?

The one in Switzerland, and the one in Durban?

How about the distiller?

Hi, Ben,

Good questions. It seems to me so important right now that we get UDDTs field tested in industrialized countries. (Better to do field trials at home before doing them elsewhere.) Public toilets are not the easiest way to launch UDDTs but the educational effect could be terrific. We're looking for successful models to advocate for with local leaders. I'm interested in what part of France you're working in.

Carol

Kai,
I would be very pleased if you could give us more information about about the urine vale chain since i am using the urine from 20,000 students to grow apples and cherries.

Please refer the details to
forum.susana.org/forum/categories/91-pro...-successful-business )
best regards
Scott

Dear Lilian, dear Scott

Please find the answers to your questions below:

1. Costs of the reactor
We did a rough calculation based on the expenditures for the pilot plants in Dübendorf and Durban. Based on this calculation, a pilot plant costs about 200 EUR per person. Approximately half of this costs are for the distiller and the other half for the nitrification reactor, the process control and all other components. For example a pilot plant, which can serve 400 people would cost approximately 80,000.- EUR. However, this value should be taken with a grain of salt, because a pilot plant is substantially more expensive than an industrially produced standard reactor. We expect that the price will be significantly lower in the future.

2. Urine value chain
A final assessment of the urine value chain in the VUNA project cannot be given yet, because the research is not completed. However, you can find our current findings on our homepage: www.vuna.ch .
In the STUN project ( www.eawag.ch/stun ) we also investigated the direct use of urine as fertiliser. This can be a valuable option in rural areas, especially if drip fertigation systems are used.

Best regards, Kai

Dear Kai:
Thank your very much for your reply. The pilot project is acceptable. I will look at the TUN project as mentioned.
Thanks
Scott

Hello great to know that you have the nitrification tank running.
I am interested in carrying out a similar lab experiment and i would want to know more about the reactor set up that you used. What type of reactor, what was the flow rate the Hydraulic retention time , the volumes the concentration of the Dissolved oxygen. Basically the methodology and reactor set up. Thank you very much

Hello

In our current system we use biofilm carriers. The fill rate is about 60%. The biofilm carriers are mixed by aeration and the oxygen concentration is therefore close to saturation. The maximum ammonia oxidation rate is about 400 gN/m³/d. The minimum hydraulic retention time can be calculated based on the ammonia concentration in the influent and the ammonia oxidation rate. For example, if the ammonia concentration in the influent is 4000 gN/m³/d, the hydraulic retention time will be 5 days, because half of the ammonia is oxidized.
The pH has to be kept in a narrow range by adjusting the influent rate. If the influent concentration and the temperature are constant, this can done by hand otherwise you might want to use a process controller, which keeps the pH in a narrow range of 0.1 units by switching the influent on and off. An optimal pH value is 6.
A detailed description of our pilot reactor can be downloaded at:
www.eawag.ch/forschung/eng/gruppen/vuna/...Udert_2013_Vancouver

Let me know, if you need any additional information.
Kai

Hello Mr. Udert,
did you anaylse the effluent N- concentrations, i.e. NH4+, NO2- and NO3- ? is so what was were there.
If the urine was partially nitrified does it mean only 50% of ammonium was converted to N03- . In that case what happened to the rest of the NH4+ when the effluent proceeded to the vacuum distiller

The rest of the ammonium is still present as NH₄⁺. Since nitrification lowers the pH value, this amount of ammonium is not lost during distillation (except for a very small fraction). I attach a paper, in which we describe the fate of ammonia during distillation in more detail.

Thank you. Oh, Yes pH drop does the trick.
Thanks for the attached and I have already read through the paper.
I was thinking of using this "hybrid membrane-aerated biofilm reactor (MABR) was
used for the nitrification experiment" as i believe i wont have easy access to the Kaldnes rings.
I have seen the reactor but if you have more pictures of it. I would be grateful as i will get a better understanding on the set-up

We added a drawing of the membrane module in the supplementary information of the paper I just sent you. BTW, you might not need biofilm carriers, the process should also work with suspended biomass, if you can ensure that the biomass is retained in the reactor or recycled from a settling tank back into the reactor.