How to minimize power in dissolved oxygen control... DSM in action

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:192105

Skrentner, R G; Lutman, C G

As part of the EPRI Municipal Water and Sewage Project, Demand-Side Energy Management, EPRI retained EMA to evaluate the life cycle cost of three alternatives for controlling low-pressure centrifugal compressors to reduce power costs. The alternatives included: inlet guide vanes, inlet butterfly valves, and adjustable speed drives. This paper contains the findings and identifies actions that could benefit wastewater treatment facilities. Many wastewater treatment plants use an activated sludge process to remove organic pollutants. In this process, a large mass of microbes consumes the organic matter in the wastewater. The microbes require diffused oxygen to metabolize the organic material. The diffused air mixes with the contents of the aeration basin and provides oxygen to the microbes. The basic activated sludge process has the following features: (1) An aeration basin with provisions for oxygenation and mixing of the mixed liquor, (2) A settling tank or clarifier to separate mixed liquor solids and liquid, (3) A sludge recycling system to return settled activated sludge to the aeration basin, and (4) A sludge wasting system to remove solids at the rate that it grows, thus maintaining the desired mass of solids in the process. The operator has three main control variables: (1) Aeration rate to control the dissolved oxygen concentration in the aeration basin. The operator sets the aeration rate to maintain dissolved oxygen at 1-2 mg/l. (2) Sludge recycle rate to control the concentration of the return sludge and the mass of solids in the clarifier. The operator sets the return rate to maintain the sludge blanket level at some predetermined depth. (3) Sludge wasting rate to control the solids retention time and mass of solids in the process. The operator sets the waste rate usually once per day to remove a pre-determined mass.

• OSTI ID: 192105
• Report Number(s): CONF-940129--
• Country of Publication: United States
• Language: English

Related Subjects

29 ENERGY PLANNING, POLICY, AND ECONOMY
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
ACTIVATED SLUDGE PROCESS
COMPRESSORS
DISSOLVED GASES
MANAGEMENT
NUMERICAL DATA
POWER DEMAND
SEWAGE