I also think it is quite hard to understand the real intention of the question as originally posted. I would assume that it is emptiers who would be interested in knowing the consistency of the faecal sludge, ideally before they arrive at the facility itself. However, I don't see a scenario of facility users doing the consistency test themselves so I think simple observation could serve the purpose.

In the case of Kampala-Uganda, vacuum truck operators usually have an idea of what sludge consistency to expect in particular areas but what I have seen them do a lot also is to pour water in pits so as to make the sludge more workable before pumping it out.

Regards,
Daniel

I agree that it would be useful if the question could be clarified. However, here are some initial thoughts, based on my own experience.

First, I would say that, in addition to septic tanks, many leach pits are pumpeable. Experience in Indonesia shows that there is sometimes a need to mix some water with the pit contents before pumping it and it is possible that some hard consolidated sludge remains in the bottom of pits (and septic tanks) that have not been pumped for some time. The research from e Thekwini in South Africa shows that some dry pit latrines contain faecal sludge that cannot be pumped but there are other places in Africa, for instance Dakar, where septage has a high water content and certainly can be pumped.

Perhaps the best way to make a quick initial assessment is to assess what is already happening. Do vacuum tankers operate and if so what does the material that they discharge look like - is it thick or thin? Of course, there is always the possibility that they are only taking the top layer from the sludge in the tank/pit but observation of existing practice and talking to tanker operators and manual emptiers will give an idea of the existing situation

Yeah, but the original question was not very detailed to begin with, and I guess the original poster should first clarify what he/she was referring to before expecting someone to spend time to write more than the general answer I provided.

Isn't the question more about methods for determining at what consistency sludge is "pumpeable" and at what point it is not, rather than generalisations about the system it came from? Wouldn't this depend on the equipment used?

In my view would be nice to have input from participants representing innovations taking place in this area... there are a range of these described in this forum, some funded by benefactors who I'm sure would like to see information flow.

cheers
Dean

That depends on the type of on-site sanitation system.
For septic tanks there is usually enough liquid to pump the majority of the sludge, but it might require some manual mixing and trying to break up the often consolidated sludge bottom.

Other on-site systems like pit latrines you can rarely pump, except maybe by adding quite a lot of water and mixing before pumping.

Hi,
I have a subject which I'd like have your opinion: ''How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not?''
Thanks