From: Jason Clifford
Sent: Mon Jan 30 13:25:46 2017
To: Gerald Fisher
Subject: RE: digesters
Importance: Normal
From: Gerald Fisher [mailto:gfisher@cityofmolalla.com]
Sent: Monday, January 30, 2017 1:16 PM
To: Jason Clifford <jclifford@cityofmolalla.com>
Subject: RE: digesters
Thanks Jason. Will be good to get some of this stuff built and online.
Regards,
Gerald Fisher, P.E. | Public Works Director
City of Molalla
117 N Molalla Ave. | PO Box 248 |Molalla, OR 97038
Office: 503.829.6855 | Direct: 503.759.0218
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From: Jason Clifford [mailto:jclifford@cityofmolalla.com]
Sent: Monday, January 30, 2017 12:38 PM
To: Gerald Fisher <gfisher@cityofmolalla.com>
Subject: digesters
Hello Gerald,
Ryan was here on Thursday. I told him I’d email you about the digester project. I recommend (2) 20,000 gallon digesters, (3) blowers; one for each digester and a backup. The three blowers should be valved so each digester can use any of the three. A submersible pump in the skimmings wet well to pump to the digesters. Repiping of the backwash and drain lines from the filters; too much clear water to the digesters will thin out the solids. Pipe from the digesters to the side road northwest of filter #2. And an FKC screw press. (2) digesters is good for maintenance, decanting and emergency storage, if needed. I’ll have a chemical supplier come and perform jar testing to get the right polymer for flocculation. After that, I’ll dial the screw press. Ideally, we would want to see about 20% dried solids (cake), to reduce dumping fees. BOD and TSS are not required for digester sizing as they’re just aerated holding tanks until the contents go through the screw press. I would usually run my press all week and turn it off on the weekends to fill the digester with fresh solids and decant as needed.
Thanks,
Jason