video: Lloyd Hecathorn Turbidity Reduction Facility

Lloyd Hecathorn Turbidity Reduction Facility field trip

F/M: Food to Microorganism Ratio

The F/M ratio is a process control number that helps you to determine the proper number of microorganisms for your system. To do this calculation, you will need the following information:

• Influent Flow into your activated sludge system (Flow MGD)
• Influent CBOD (mg/l) concentration into your aeration tank.
• Mixed Liquor Volatile Suspended Solids Concentration (mg/l)
• Volume (in gallons) of your aeration system

The term Food to Microorganism Ratio (F/M) is actually a measurement of the amount of incoming food ( Lbs of Influent CBOD) divided by the Lbs of Microorganisms in your system. Some calculations also include the volume of activated sludge in your clarifiers, the one demonstrated here does not. If you have an activated sludge system, you should determine your F/M ratio regularly.

To determine the amount of incoming food (F), you need to know the CBOD of the influent into your activated sludge(aeration) system. You also need to know the flow(MGD). So to calculate the amount of food we do the following calculation:

F= Influent Flow (MGD) X Influent CBOD Concentration (mg/l) X 8.34

To determine the volume of microorganisms (M), you need to know the volume of your aeration system and you need to know the concentration of Volatile Solids in your aeration system (MLVSS) or Mixed Liquor Volatile Suspended Solids. To calculate the microorganisms, we do the following calculation:

M= Aeration System Volume (in Millions of Gallons) X MLVSS X 8.34

To Calculate the Ratio: F/M

Example:

Facility Flow = 1.2 MGD Influent CBOD= 230 mg/l
1.2 X 230 X 8.34 = 2301.84 Lbs Coming In
F= 2301

Aeration System Volume 250,000 gal / 1,000,000 = 0.25MG
MLVSS = 2500mg/l
0.25 X 2500 X 8.34 = 5215 Lbs of Microorganisms under Aeration
M = 5212

2301/5212 = 0.44 F/M Ratio

info from Pennsylvania Dept of Environmental Protection
______

online F/M Calculator

Regional Water Board public workshop tonight

Staff of the North Coast Regional Water Quality Control Board (Regional Water Board) has scheduled a public workshop to update local stakeholders on the development of the Elk River Sediment Total Maximum Daily Load (TMDL). The meeting will provide an opportunity for staff to describe the TMDL development process, status of the project and tentative time frames for implementation actions. It will also provide an opportunity for discussion and public input regarding staff’s preliminary recommendations on technical and policy approaches to the TMDL.

Agricultural Services Building
5630 South Broadway Eureka, CA
November 10, 2009
6:30 – 8:30 pm

Available documents pertaining to the Elk River TMDL may be viewed and downloaded here

Documents include:

•A summary report from the October 1, 2009 Regional Water Board meeting;

•Preliminary review drafts of Chapters 1 (Introduction) and 2 (Problem Statement) of the Elk River TMDL Staff Report;

•A summary of comments received during the California Environmental Quality Act (CEQA) scoping period for the Elk River Sediment TMDL;
•A variety of available documents pertinent to the development of the Elk River Sediment TMDL; and
•Instructions regarding how to sign-up for mailing lists to receive future notifications relating to the Elk River Sediment TMDL.

Contact information:
Adona White
5550 Skylane Blvd., Suite A
Santa Rosa, CA 95403
(707) 576-2672
AWhite@waterboards.ca.gov

note:
The North Coast Regional Water Quality Control Board (Regional Water Board) and the U.S. Environmental Protection Agency (EPA) have listed the Elk River watershed under the Clean Water Act Section 303(d) as a sediment impaired waterbody. A program has been developed to recover 303(d) List waterbodies via the establishment of Total Maximum Daily Loads (TMDL). At this time, the Regional Water Board staff is in the process of establishing a TMDL for sediment in the Elk River watershed. The goal of the TMDL program is to restore and maintain the sediment impaired beneficial uses of water of Elk River and its tributaries. Staff will develop the technical TMDL, the implementation, and monitoring plans together.

photos: Eureka Wastewater Treatment Plant

I have posted photos from the field trip to the Eureka Wastewater Treatment Plant at Flickr