This sounds like an course-work assignment that tried to capture a really complex topic in a simple question. Most likely they just want you to figure out typical sludge accumulation rates which can be found in the standard text-books and many online sources (you will have to do the research yourself, Edit or see the links posted above).

If the question is really meant to go into more detail, there if for example the work put into "Shit-Flow-Diagrams", see: sfd.susana.org/ that tries to explore more what really happens to all the excreta of a city (and thus also what of it ends up at a treatment facility).

Thanks Elisabeth and the team. Your feedback has been useful.

Dear Bossman,

Welcome to the forum! I think you'll find a wealth of information in this thread on the forum:
forum.susana.org/214-vault-content-resea...-from-pits-tanks-etc
It had the title Quantities of faecal sludge from pits, tanks etc and several SuSanA members made very in-depth posts in that thread (don't forget to look at the second page of the thread as well).

You'll also find useful information in this sub-category: forum.susana.org/214-vault-content-resea...acteristics?start=20
(it is called "Pit or vault content research and faecal sludge characteristics" and also has two pages)

Please tell us more about your work. Is it part of an assignment or of an MSc thesis? Where are you studying?

Regards,
Elisabeth

I am Bossman, studying Environmental Science in Ghana.

How do l calculate the capacity of a new faecal sludge/septage treatment facility...taking into consideration variables like open defecation, reuse technologies like biogas digestors whose input materials will not end up at the septage treatment facility.

All l have to work with is the population size, population growth rate and some estimates of open defecation.

I know that l should consider faceal accumulation rates etc. in my estimates.

Please assist.