1. Glossary Frank Spellman

Activated sludge

the solids formed when microorganisms are used to treat wastewater using the activated sludge treatment process. It includes organisms, accumulated food materials, and waste products from the aerobic decomposition

process.

Advanced waste treatment

treatment technology used to produce an extremely high quality discharge.

Aerobic

conditions in which free, elemental oxygen is present. Also used to describe organisms, biological activity, or treatment processes that require free oxygen.

Anaerobic

conditions in which no oxygen (free or combined) is available. Also used to describe organisms, biological

activity or treatment processes that function in the absence of oxygen.

Anoxic

conditions in which no free, elemental oxygenis present. The only source of oxygen is combined oxygen, such as that found in nitrate compounds. Also used to describe biological activity of treatment processes that function only in the

presence of combined oxygen.

Average monthly discharge

limitation the highest allowable discharge over a calendar month.

Average weekly discharge limitation

the highest allowable discharge over a calendar week.

Biochemical oxygen demand (BOD)

the amount of organic matter that can be biologically oxidized under controlled conditions (5 days @ 20C inthe dark).

Biosolids

solid organic matter recovered from a sewage treatment process and used especially as fertilizer (or soil amendment); usually used in plural (from Merriam-Webster’s Collegiate Dictionary, 10th ed., 1998)

Buffer

substance or solution which resists changes in pH.

Carbonaceous biochemical oxygen demand (CBOD5)

the amount of biochemical oxygen demand that can be attributed to carbonaceous material

Chemical oxygen demand (COD)

the amount of chemically oxidizable materials present in the wastewater.

Clarifier

device designed to permit solids to settle or rise and be separated from the flow. Also known as a settling tank

or sedimentation basin

Coliform

type of bacteria used to indicate possible human or animal contamination of water.

Combined sewer

collection system that carries both wastewater and storm water flows.

Comminution

process that shreds solids into smaller, less harmful particles.

Composite sample

A combination of individual samples taken in proportion to flow

Daily discharge

the discharge of a pollutant measured during a calendar day or any 24-h period that reasonably represents

a calendar day for the purposes of sampling. Limitations expressed as weight is total mass (weight) discharged over the

day. Limitations expressed in other units are average measurements of the day.

Daily maximum discharge

the highest allowable values for a daily discharge.

Detention time

the theoretical time water remains in a tank at a given flow rate.

Dewatering

removal or separation of a portion of water present in a sludge or slurry.

Discharge monitoring report (DMR)

the monthly report required by the treatment plant’s National Pollutant Discharge Elimination System (NPDES) discharge permit.

Dissolved oxygen (DO)

free or elemental oxygen that is dissolved in water.

Effluent

the flow leaving a tank, channel, or treatment process.

Effluent limitation

any restriction imposed by the regulatory agency on quantities, discharge rates, or concentrations of pollutants that are discharged from point sources into state waters

Facultative

organisms that can survive and function in the presence or absence of free, elemental oxygen.

Fecal coliform

a type of bacteria found in the bodily discharges of warm-blooded animals. Used as an indicator organism.

Floc

solids which join together to form larger particles which will settle better.

Flume

flow rate measurement device.

Food-to-microorganism ratio (F:M)

activated sludge process control calculation based upon the amount of food (BOD or COD) available per pound of mixed liquor volatile suspended solids.

Grab sample

Grit

heavy inorganic solids such as sand, gravel, egg shells, or metal filings.

Industrial wastewater

wastes associated with industrial manufacturing processes.

Infiltration/inflow

extraneous flows in sewers; water discharged into sewer pipes or service connections from such sources as foundation drains, roof leaders, cellar and yard area drains, cooling water from air conditioners, and other clean-water discharges from commercial and industrial establishments.

Infiltration

water entering the collection system through cracks, joints, or breaks.

Steady inflow

water discharged from cellar and foundation drains, cooling water discharges, and drains from springs and swampy areas. This type of inflow is steady and is identified and measured along with infiltration.

Direct flow

those types of inflow that have a direct stormwater runoff connection to the sanitary sewer and cause an almost immediate increase in wastewater flows. Possible sources are roof leaders, yard and areaway drains, manhole covers, cross connections from storm drains and catch basins, and combined sewers.

Total inflow

the sum of the direct inflow at any point in the system plus any flow discharged from the system upstream through overflows, pumping station bypasses, and the like.

Delayed inflow

stormwater that may require several days or more to drain through the sewer system. This category can include the discharge of sump pumps from cellar drainage as well as the slowed entry of surface water through manholes in ponded areas

Influent

the wastewater entering a tank, channel, or treatment process.

Inorganic

mineral materials such as salt, ferric chloride, iron, sand, gravel, etc.

License

a certificate issued by the state board of waterworks or wastewater works operators authorizing the holder to perform the duties of a wastewater treatment plant operator.

Mean cell residence time (MCRT)

the average length of time a mixed liquor suspended solids particle remains in the activated sludge process. May also be known as sludge retention time.

Mixed liquor

the combination of return activated sludge and wastewater in the aeration tank.

Mixed liquor suspended solids (MLSS)

suspended solids concentration of the mixed liquor.

Mixed liquor volatile suspended solids (MLVSS)

the concentration of organic matter in the mixed liquor suspended solids.

Milligrams/Liter (mg/L)

a measure of concentration. It is equivalent to parts per million.

National Pollutant Discharge Elimination System permit

permit that authorizes the discharge of treated wastes and

specifies the condition, which must be met for discharge.

Nitrogenous oxygen demand (NOD)

a measure of the amount of oxygen required to biologically oxidize nitrogen compounds under specified conditions of time and temperature.

Nutrients

substances required to support living organisms. Usually refers to nitrogen, phosphorus, iron, and other trace metals.

Organic

materials that consist of carbon, hydrogen, oxygen, sulfur, and nitrogen. Many ____ are biologically degradable.

Pathogenic

disease causing, is capable of causing illness.

Point source

any discernible, defined, and discrete conveyance from which pollutants are or may be discharged.

Part per million (ppm)

an alternative (but numerically equivalent) unit used in chemistry is milligrams per liter.

Return activated sludge solids (RASS)

the concentration of suspended solids in the sludge flow being returned from the settling tank to the head of the aeration tank.

Sanitary wastewater

wastes discharged from residences and from commercial, institutional, and similar facilities that include both sewage and industrial wastes.

Scum

the mixture of floatable solids and water that is removed from the surface of the settling tank.

Septic

a wastewater that has no dissolved oxygen present. Generally characterized by black color and rotten egg (hydrogen sulfide) odors.

Settleability

process control test used to evaluate the settling characteristics of the activated sludge. Readings taken at 30 to 60 min are used to calculate the settled sludge volume and the sludge volume index.

Settled sludge volume (SSV)

the volume in percent occupied by an activated sludge sample after 30 to 60 minutes of settling.

Sewage

wastewater containing human wastes.

Sludge

the mixture of settleable solids and water that is removed from the bottom of the settling tank.

Sludge retention time (SRT)

see mean cell residence time.

Sludge volume index (SVI)

a process control calculation that is used to evaluate the settling quality of the activated sludge. Requires the SSV30 and mixed liquor suspended solids test results to calculate.

Storm sewer

collection system designed to carry only storm water runoff

Storm water

runoff resulting from rainfall and snowmelt

Supernatant

the amber-colored liquid above the sludge that is in a digester.

Wastewater

water supply of the community after it has been soiled by use.

Waste activated sludge solids (WASS)

the concentration of suspended solids in the sludge, which is being removed from the activated sludge process.

Weir

device used to measure wastewater flow.

Zoogleal slime

the biological slime which forms on fixed film treatment devices. It contains a wide variety of organisms

essential to the treatment process.