Common Wastewater Acronyms

AOB: Ammonia oxidizing bacteria. Autotrophic organisms that perform nitrification through forming nitrite and then nitrate

BOD: Biological Oxygen Demand. A test using the amount of oxygen consumed by bacteria (typically over 5 days) to determine the strength or measure of pollution

TOC: Total Organic Carbon. A measurement of pollution or the strength of a waste performed by measuring the amount of total organic carbon present

DO: Dissolved Oxygen

ORP: Oxidation Reduction Potential. This is a measurement of the oxidation potential of the wastewater that is expressed in mV. As ORP increases, the material is more oxidized. Negative ORP can be thought of as negative dissolved oxygen

SOUR: Specific Oxygen Uptake Rate. This includes the concentration of suspended solids and is commonly reported as the amount of oxygen in mg utilized by one gram of volatile suspended solids/hour

SV30: The volume that the sludge settles to after 30 minutes of the standard settleability test

SVI: Sludge Volume Index. A good quality sludge tends to have an SVI between 50-150

PAO: Polyphoshate accumulating organism. These are organisms that are desired in enhanced biological phosphorus removal due to their ability to take up extra phosphorus (luxury uptake) in the aeration tank

Q: Often an abbreviation used for flow

MLSS: Mixed Liquor Suspended Solids

F/M ratio: The amount of food (lbs/day or kg/day of BOD) divided by the amount of microorganisms (lbs of kg of volatile suspended solids in the aeration tank).

VSS: Volatile Suspended Solids. This, or MLVSS, is a measurement that reflects the solids in the system that are living

MGD: Million Gallons per Day

GPM: Gallons per Minute

WAS: Waste Activated Sludge. The solids that are wasted from the system to maintain the proper balance of food and microorganisms

RAS: Return Activated Sludge. This is the sludge that settles out in the clarifier and is pumped back to the head of the aeration tank