Hi Rowan,
Nice to hear those ideas.
Some 15 years ago Ralf Otterpohl (I guess??) made a simulation on the behavior of the Hamburg WWTP, if instead of enlargement for nitrification and denitrification the city would introduce a consequent separation of urine. Unfortunately I only remember that it has been done and the results were interesting, but I don´t have the study-paper. I think it would be great to take this point up again in circumstances where there is need for nutrient removal in existing treatment plants and therefore large investment volumes are needed. Especially if you are able to keep out of the sewer the typical "urine producers" as: Stadiums, workplaces with lots of people, the point might be interesting.
Just to mention some economic aspects:
• The volume needed for nitrification and denitrification is bout the double of just carbon removal less investment
• The process is much easier - stable to run without nitrification and denitrification easier operation
• There is no need for internal backflow less energy, less operational costs
• The energy consumption of the aerobic treatment for aeration can be cut down very much.
• The sludge age can be lower and therefore the energy content of the sludge is higher possibility of energy gain in digestion
• The urine can be transformed to struvite and therefore be a source of P (larger volumes of concentrated liquor with high contents of P are already today economically possible)
As well I heard that in Sweden (again no real reference, maybe someone of Sweden could help with that) the new houses had (I think it changed, so today it is different again) to have a urine separation installed even though still the urine goes into the sewer...but in future may be not...and in this case the house (which is the most complicated part) is already ready to roll.
I know that Durban is looking into this possibility as well as they do have the problem so they might be an address for exchange. I don´t know until what point they came.
Regarding the other end (the toilet)….when we started with the UDDT in Peru our main focus was to get middle class (or more) bathroom fotos with UDDT in order to show the general applicability. Today there should be enough examples available but if you need something let me know. Didn´t even look if this category in flickr exists…middle class UDDT bathrooms.
As I realized that new people do not have the possibility to know the people who are writing since a longer time.. I´m a sanitary engineer with a sanitation company in Brazil and Peru and doing consultancy in other countries of LA.
Yours
Christoph Platzer
www.rotaria.net