Perry L Schafer

US Patent:

7833415, Nov 16, 2010

Filed:

Oct 25, 2006

Appl. No.:

11/585842

Inventors:

Sudhir N. Murthy - Washington DC, US
John T. Novak - Blacksburg VA, US
Glen T. Daigger - Parker CO, US
Perry Schafer - Sacramento CA, US
Christopher Peot - Washington DC, US

Assignee:

D.C. Water & Sewer Authority - Washington DC

International Classification:

C02F 3/00

US Classification:

210605

Abstract:

An improved process for sludge treatment includes anaerobic digestion followed by post-mesophilic aerobic and/or anoxic digestion. The first anaerobic step may be performed under either mesophilic or thermophilic conditions. The subsequent aerobic/anoxic digestion may be performed using either simultaneous, sequential or pulsed aerobic and anoxic conditions. An apparatus for performing the improved sludge treatment may be one digester for performing the anaerobic followed by aerobic/anoxic digestion. Alternatively, the system for performing the improved sludge treatment techniques may be at least two digest reactors.

US Patent:

20040011718, Jan 22, 2004

Filed:

Apr 28, 2003

Appl. No.:

10/425131

Inventors:

Clifford Arnett - Columbus GA, US
Joseph Farrell - Cincinnati OH, US
Daniel Hull - Atlanta GA, US
Steven Krugel - Seattle WA, US
Perry Schafer - Sacramento CA, US
Billy Turner - Columbus GA, US
Warren Uhte - Fort Jones CA, US
John Willis - Norcross GA, US

Assignee:

Columbus Water Works

International Classification:

C02F011/04
C02F003/00

US Classification:

210/175000, 210/609000, 210/603000, 210/613000

Abstract:

A method of treating wastewater sludge includes pumping, continuously, raw sludge into a first digester and treating the raw sludge at a specific temperature of between about 51 C. to 60 C.; transferring the treated wastewater sludge to a batch tank; treating the wastewater sludge in the batch tank, anaerobically, at a thermophilic temperature which is not more than 2 C. warmer than the specific temperature in the first digester; and disposing of the treated wastewater sludge as a Class A biosolid. A wastewater sludge treatment system includes a first thermophilic digester for treating raw wastewater sludge at a specific temperature in a range of between about 51 C. to 60 C., and discharging a treated wastewater sludge; a batch tank for receiving the treated wastewater sludge discharged from the first digester and for thermophilically treating sludge at a temperature in a range of between about 51 C. to 60 C. and not more than 2 C. warmer than the specific temperature in the first digester, for between about 0.5 hours and 5 hours; and a disposal mechanism for disposing of the treated wastewater sludge as a Class A biosolid.