----- Original Message -----
From: Martin J. Thomas <Martin.J.Thomas@rose-hulman.edu>
To: Kevin Sutterer <Kevin.Sutterer@rose-hulman.edu>
Cc: Cathy Colwell <colwell@mindspring.com>; Martin Thomas
<Martin.Thomas@rose-hulman.edu>
Sent: Thursday, February 03, 2000 11:16 AM
Subject: Re: Research Project at Mainland High School, Daytona Beach, FL

Hi,

Kevin Sutterer forwarded your message to me.  The idea certainly will
work.  I do have several comments.

In most waste water treatment plants (WWTPs), pumps are used to
transport the wastewater to the first treatment operation then gravity
drives the flow from there on (no other pumps, it flows "downhill").
Putting the sludge digesters on top will probably incur lower pumping
cost since the sludge volume is a lot smaller than the incoming flow
volume (probably 1 or 2% of incoming flow).  With the wastewater
treatment below the digesters, your pumping cost will be lower.  Also,
some digesters have floating covers and need to be open to air to vent
any leaks.  (also methane generation in the basement isn't safe).

Some terminology. Your incoming flow seems to be labeled "sludge in).
Sludge is the wrong word.  Correct term is wastewater or domestic
sewage.  Sludges are the concentrated residuals from treatment
processes.

Typical domestic wastewater is about 0.02%  (200 mg/L) solids, typical
anaerobic digester sludge may be 4-5% (50,000 mg/L).

Don't know if this will help but feel free to e-mail back.

Martin Thomas
Prof. of Env Eng
RHIT