Sludge accumulation rates in an ABR based on daily inflow of 40m3 of faecal sludge?

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  • macador
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Sludge accumulation rates

Hello all,

Can anyone please advise on sludge accumulation rates in an ABR (or several run in parallel) based on daily inflow of 40m3 x 5 days per week of FS with the characteristics seen in the attached excel file?

Presumably dimensioning will be key, but is there much room to play around with the dimensions or are they relatively fixed? Using the DEWATS spreadsheets it was unclear to me how much we could increase the volume of the chambers by increasing the width without reducing treatment efficiency.
To deal with the accumulated sludge we plan on using unplanted drying beds, but the quantity and dimensions will largely depend on the accumulation rate in the ABRs.
Any help would be much appreciated.

Cheers,

owen

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  • Elisabeth
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Re: Sludge accumulation rates in an ABR based on daily inflow of 40m3 of faecal sludge?

Hi Owen,
I see you didn't get a response yet so I'll try to help you by putting this thread back to the top of the list. If you received some answers via other means in the meantime, please do put them into this thread as well.

So your input flow into the ABR is faecal sludge? I thought ABRs were meant to take sewage, I wasn't aware that they can also treat faecal sludge. Is the design spreadsheet that you mentioned intended for ABRs receiving faecal sludge? Could you provide a link to that spreadsheet or attach it?

I would have thought the first step of any faecal sludge treatment is normally dewatering. (see also here for more on faecal sludge treatment: forum.susana.org/280-faecal-sludge-treatment )

If anyone can help Owen out with some advice, tips or questions, please put them into this thread. I am sure he'll appreciate it. Thanks.

Elisabeth
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  • macador
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Re: Sludge accumulation rates in an ABR based on daily inflow of 40m3 of faecal sludge?

Thanks Elisabeth,

We were trying to work out whether it would be possible to skip the liquids-solids separation pre-treatment and go direct to the ABR, but I think following consultation with several more people it seems clear that this would not be advisable.

Now we are looking at having two settling-thickening tanks that can be loaded for up to a month (one at a time) before desludging to an unplanted drying bed. The overflow from the tanks would feed the ABRs (three in parallel). We also would like to design for approx. 55m3 / day for 5 days / week.

I believe the original excel tool was developed from the Sasse calculations (so for wastewater), but we are now using modified versions (as attached).

We are also not sure what the next treatment step should be. A horizontal sub-surface flow constructed wetland is an option, but the area required and the costs involved are quite high.

Any thoughts would be much appreciated.

Cheers,

owen

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