Guidance on dewatering sludge and separating solid waste from the solids
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TOPIC: Guidance on dewatering sludge and separating solid waste from the solids

Re: Guidance on dewatering sludge and separating solid waste from the solids 05 Jun 2014 07:22 #8877

  • BStalker
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I will look through the thread now, thanks for the help again

Bob

Re: Guidance on dewatering sludge and separating solid waste from the solids 06 Jun 2014 01:08 #8888

  • jonpar
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Dear Christoph

You can clearly understand my line of thinking.. and sounds like you've already been there, which is good. This is what I like about the SuSanA forum... the more we are open about what we are thinking, the more we have the opportunity to interact and learn from eachother.

Like you I have looked at various technologies that might provide the solution and they all seem to be polymer based.. so not keen on those. I found information the SALSNES filter and was hoping that this would do the job but unfortunately not as the filter doesn't like septic waste waters. Perhaps planted drying beds are the best solution but that takes more land.....

Which leads to the next point that you raise.. which is why bother in the first place... well... the proposed treatment plant in Freetown is 25-30 km away. We've not done any detailed calculations but my gut feeling is that this is too far to be transporting septage .. especially because in many cases, water is used for desludging and the septage is more like wastewater than fecal sludge.

There are a couple of sites used by Freetown city council for solid waste disposal.. and these could potential be used for this purposed.. in due course, I'll tell you what we put forward in our recommendations to FCC.

I can't answer our questions about dry fermentation vs CSTR but will look into it. I will look more at hydraulic thickening too but as you say, it may not be worth it.

Thanks again for your useful reply.

best regards,

Jonathan
Jonathan Parkinson
B.Eng (Hons) MSc DIC PhD
Integrated Sanitation Solutions (i-San) Consulting
Email : jonathan.parkinson@i-san.co.uk
Skype / V-mobile : Jonathanparkinson1
Telephone: + 44 20 300 48528
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Re: Guidance on dewatering sludge and separating solid waste from the solids 06 Jun 2014 05:46 #8890

  • AquaVerde
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Dear Jonathan,

water is used for desludging and the septage is more like wastewater than fecal sludge.

I am guessing, maybe you are dealing with very similar problems like the colleagues in Dakar?

"...Any sewage nearly without fecal sludge, as it is currently delivered by Dakar's "honey-suckers", would have no caloric/financial value for the biogas-service providers, therefore less payments. This means, in order to keep quality of delivered FS the "honey-suckers" are paid by the fecal sludge content (TS) delivered only.

Having an energy producing system with an open & transparent financial interests involved, will minimize illegal dumping, as the owner of "honeysuckers" would loos profit and additional it would avoid e.g. costly "gadget systems" of distrust like GIS-traking of the whereabouts of "honeysuckers" and avoid too high maintenance intensive de-watering of FS (Omni-Ingestor) at the spot. For the time being, not functional lance nozzle at nearly all Dakar's "honeysuckers", would be repaired by the owners (without "capacity building"), as functional lance nozzle would increase fecal sludge content during collection...
"

In general terms, a "rolling" sewage collection system is always the most expensive system (total over the time) in comparison to piped and is mainly based on current very cheap energy costs for diesel (fossil energy) and cheap labor cost. At least energy prices will increase for sure as availability of fossil energy is shrinking. Keeping this in mind it is up most important to "design" systems for a long term future which most as possible less "rolling" transport costs, which means you can not avoid the hassle (as Christoph described rightly) having many decentralized treatment points for transported FS, regardless AD or Composting systems.

A decentralized treatment system like that should be in the hand of one operator/management (organization) only. Additional, having many smaller treatment systems might reduce the complexity and would be more resilient in comparison to one or two larger centralized treatment systems/points. If one of this decentralized and smaller treatment systems/points is temporary out of order it would not affect the whole system as it could be the problem of a centralized system with one/two point of treatment.

Just for a ponder, in Germany communal owned sanitation companies with sanitation systems in rural areas having large scale piped collection systems, already drafting plans, Universities and think tanks discussing about to cut down this pipe networks to go for more decentralized systems. By replacing then worn out sewage pump station against smaller wwtp's with a kind of DEWATS, in order to have less energy- and O&M costs. Existing large scale wwtp's will then be reduced partly and maybe used for others. They looking already now further for possible changes, last not least to avoid financial collapses.

This is just my opinion.
Detlef
www.aqua-verde.de
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Last Edit: 06 Jun 2014 18:49 by AquaVerde.
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