Dear all,

Let me first introduce myself shortly: I am Ludo Jacobs, since August 2011 working for the Water and Sanitation Development Facility North in Uganda as an Advisor Sanitation (with a contract of German GIZ).

My question is about the maximum BOD loads (in kg BOD/ha/d) that anaerobic and facultative ponds for pre-settled sewage water can cope with in the Ugandan situation (in the North).

If anyone has some useful data I would appreciate it very much if she/he can share this information with me. Thanks a lot.

Dear Ludo,
Welcome to the forum! The following reply reached us from Christoph Platzer (Brazil):

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Facultative ponds: 220 - 300 kgBOD/ha/d at temperatures where the coldest month is 20-24 °C. (or even 200 kgBOD/ha/d)

See for example Pearson and Mara:
books.google.com.br/books?id=kKTkZwEACAA...nHCw&ved=0CEQQ6AEwAw

I would not use anaerobic ponds due to various reasons, the principal reason is the odour and the second most important is the methane - problem of global warming effect.
I would use a modified UASB - lagoon. Dimensioning as a UASB with large detention time, not as an anaerobic lagoon. So I would use 12-15 h hydraulic detention time, 30 days sludge age. (both criteria have to be managed, normally the hydraulic criteria is the relevant one) literature could be v. haandel & lettinga
books.google.com.br/books?id=d9O9Gw_3rOU...tinga%20UASB&f=false

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Greetings from Kampala,
Elisabeth

Just one complement which was lost in the translation. The UASB - lagoon has to be covered.
Christoph

Hi

Im Tyrel Maddocks from South Africa.

Sludge ponds can be cured of smells with a day or two by making use of Bioremediation solution at the inflow points of sludge ponds. As opposed to waiting for sludge to dry out, one can effectively speed up the decay process of sludge deposits, therefore resulting in pond clearing out faster that the drying process (provided there are no other forms of detergents, chemical or acid based products are used). The total elimination of smells will take place regardless of the inflow rate or existing rate or level of the ponds.

Tyrel Maddocks
Maximum Output Solutions Trading CC.
M.O.S.T
+27 33 387 7600
+27 76 082 1995


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Dear Elisabeth,

Thanks for your response. Okay, an UASB lagoon, I got your point.
But then still my question: what would be the BOD load in kg/ha/d?

Kind regards,

Ludo.

Dear Ludo,

The UASB is not sized based on the area loading (kg/ha/d) but based on the hydraulic retention time and the sludge age, as Christoph said. E.g. if you were to use just the HRT, then multiply your flowrate (m3/d) with the HRT (in d) and then you get the volume. And you have to make sure the sludge age is right. Have you looked at those references which Christoph provided? Do you have to design it yourself or is someone else doing the design?

Dear Tyrel,
The discussion about such additives is already elsewhere on this forum, I have moved it to below a previous discussion on pit additives. Perhaps you can react to my previous comments here:
forum.susana.org/forum/categories/53-fae...sanitation-solutions

Regards,
Elisabeth