We have a new publication from my group, the Pollution Research Group, and co-workers which came out of the VUNA project:
Evaluation of an automated struvite reactor to recover phosphorus from source-separated urine collected at urine diversion toilets in eThekwini

The details are below and the journal Water SA provides free access to the papers, so no paywall to worry about:

Grau, MGP, Rhoton, SL, Brouckaert, CJ and Buckley, CA. (2015) Evaluation of an automated struvite reactor to recover phosphorus from source-separated urine collected at urine diversion toilets in eThekwini. Water SA Vol 41 No 3, pp383 - 389. dx.doi.org/10.4314/wsa.v41i3.10


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Note by moderator:

You can see the e-view version of the paper here:
www.wrc.org.za/Pages/Preview.aspx?ItemID...2015%2526start%253d1

To download the pdf file you need to login here:
www.wrc.org.za/Pages/DisplayItem.aspx?It...ril+2015%26start%3d1

The first page of the paper is available here (without having to log in):
www.wrc.org.za/Lists/Knowledge%20Hub%20I...33%20%20abstract.pdf

ABSTRACT

In the present study we attempted to develop a reactor system to recover phosphorus by struvite precipitation, and which can be installed anywhere in the field without access to a laboratory. A reactor was developed that can run fully automated and recover up to 93% of total phosphorus (total P). Turbidity and conductivity signals were investigated as automation proxies for magnesium dosage, thus making laboratory phosphate measurements to determine the exact magnesium dosage unnecessary. Conductivity is highly influenced by the dosing parameters (molarity and pump speed) and turbidity is affected by particle size distribution issues. Algorithms based on both conductivity and turbidity signals were not able to detect the precipitation endpoint in real time. However it proved possible to identify the endpoint retrospectively from the conductivity signal, and thereafter to dose an algorithm-calculated volume of urine to use up the excess magnesium dosed.

Keywords: struvite precipitation, human urine, turbidity, conductivity, automation, magnesium dose, VUNA

Another note by moderator (EvM):
Proud to see my paper from 2001 about struvite crystallisation cited in this paper - look for Munch and Barr (2001).

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Note by moderators: This post was made by a former user with the login name ChrisBuckley who is no longer a member of this discussion forum.

Congratulation to all the team !

This project is a great reference. This is an amazing seed that you just shared with us, I have no doubt that a lot of practicioners will start growing trees out of this research all around the world.

Looking forward to be in 10 years time, when there will be nitrification reactors just everywhere !

Best,

Ben

Dear Susana Forum members

We are happy to announce that the final report of the VUNA Project is now accessible on www.vuna.ch

The final report gives a concise and quick overview of all activities within the VUNA Project:

Urine treatment processes

• Complete nutrient recovery
• Nitrification
• Distillation
• Electrolysis
• Struvite precipitation
• Process control

Risks of using urine

• Removing pharmaceuticals
• Inactivating pathogens

Agriculture

• Fertiliser trials

Urine collection networks

• Optimising urine collection
• Performance modelling

Social and economic aspects

• Social acceptance
• Campaigning for health and hygiene
• Incentives for urine production
• Business model

We thank all sponsors for the financial support and guidance. The VUNA Project was initiated by the Bill & Melinda Gates Foundation, which also provided most of the funding. Additional funding was provided by the Swiss National Science Foundation, the United States National Science Foundation, and the project partners. We also thank all researchers, field workers, laboratory and administrative staff for their great commitment to the project.

Best regards
Teddy Gounden, Bastian Etter and Kai Udert

Elisabeth:
The urine processor is very useful. I need it.
best regards
Sott

[Start of Page 4 of the discussion]


I will start with suspended biomass and ensure the biomass isn't washed out and recycling just incase.
Thanks a lot.

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.

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

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.

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

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 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

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