human waste?

Digester design and construction info

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besim
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human waste?

Post by besim » Mon Apr 14, 2003 10:47 pm

Hello, and thank you for supporting such an instructive forum. As I'm not a native speaker of English, I also apologize for my possible mistakes in my sentences Image

I'm a mechanical engineer that is interested in anaerobic digestors. Currently, I'm research assistant in Middle East Technical University dept. of Engineering Sciences (very recently got my Ph.d.)

As the topic implies, I'm wondering whether the wastewater that is produced by human population (from 5 up to 100) can produce effective methane. I have experinced some numbers in the digester calculator that you have supplied, yet, the waste I'm concerned with contains all (I mean all) waste that men may produce in water, such as toilet papers, hygienic peds, nylon (yes, even that can enter), kitchen waste and cleaning by-products (soap, detergent, etc.) that enters within the waste water system.

I have read some recent papers on the effect of such inhibitors on the production of methane in anaerobic process, but all of these were as the name imlies "academic work", which are experimented in very controlled labaratories.

It is possible to prevent the presence of solid wastes such as paper and nylon by a filter, yet, there still may exist some detergent and soap by-products, and also ozone and/or chlorine.

I'd appreciate any experiences that the members of the forum may have that can relate to the system I consider.

Thanks for your interest.

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Bob
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Post by Bob » Sun Apr 20, 2003 10:43 am

"I'm wondering whether the wastewater that is produced by human population (from 5 up to 100) can produce effective methane."

By itself, I would think not, besim. (Of course I don't know exactly what 'effective' means to you, either.) Using the calculator, it looks like the waste from 100 people with no other additions would generate about 90 CF/day. Toilet paper would be a desirable addition, as it would increase the C:N ratio. Probably kitchen wastes would also. Hygienic pads, nylon and other non-biodegradables should obviously be screened out, if for no other reason that they would likely foul the system and pumps, etc. Soaps and detergents should be used with caution, evaluated on a case by case basis. There are some that are not harmful.

Bottom line, I think of these small systems would necessarily require some training on the part of end-users, to be effective.

What is your application? Are you interested primarily in wastewater treatment? Or is the biogas production of significant interest also?

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