Accuracy
More...
Accuracy is the extent to which a given measurement agrees with the standard value for that measurement.


 
Aeration
More...
Aeration is the addition of oxygen to wastewater.  Aeration chambers are used in packaged and extended aeration plants to provide an aerobic environment for the bacteria breaking down the organic matter.  RBC's and trickling filters add oxygen in another manner.  Step aerators are often used at the end of the treatment process to increase the DO levels before releasing the effluent.  


 
Aerobic
More...
Aerobic respiration is respiration in the presence of oxygen.  Aerobic respiration breaks down organic waste into carbon dioxide and water.


 
Age of Microbes
More...
In wastewater treatment processes, the right mix of microbes must be present to have proper removal of contaminants and for proper settling.  In aerobic decomposition, the filamentous type organisms are older, while single cell organisms are younger.  A mix of the two types is required for proper settling.


 
Ammonia (NH4OH) to Nitrate (NO3)
More...
Microorganisms within soil and water convert ammonia that comes from decaying matter into nitrates which plants can use.  The amount of ammonia which can be released into a waterway is listed on the National Pollution Discharge Elimination System (NPDES) permit issued to a plant.  Packaged plants and extended aeration plants do not efficiently remove ammonia from water, so they are largely being replaced by plants using RBC's, trickling filters, and oxidation ditches.


 
Anaerobic
More...
Anaerobic respiration is respiration in the absence of oxygen.  Anaerobic respiration breaks down organic wastes, resulting in foul-smelling gases.  Since anaerobic bacteria use so much of their time and energy scrounging for oxygen, they take longer to digest organic matter in water than aerobic bacteria do.


 
Bacteria - Types
More...
There are three main types of bacteria - aerobic, anaerobic, and facultative.


 
Bar Screen
More...
A bar screen catches large objects prior to entering water treatment and wastewater treatment processes.


 
Belt Press
More...
A belt press is a mechanical device that squeezes spent sludge through a series of rollers and separates water from sludge.  A polymer is added to induce the sludge to floc much the same way as potable water is flocked during treatment.


 
Bioassays
More...
Bioassays are sets of scientific sampling and data taken from particular sites such as streams, soils, wildlife, etc., which can be used to determine both the short and long-term impact of environmental conditions.


 
BOD
More...
Biochemical Oxygen Demand (BOD) is the quantity of oxygen used by microorganisms in the aerobic stabilization of wastewater.  It is a measure of the amount of organic matter, or food for the microorganisms, in the wastewater.  A standard five-day test is used to determine three factors: the strength of municipal wastewater, efficiency of treatment, and the amount of organic pollution in surface water.


 
Centrifugal Separation
More...
Centrifugal separation is a method of concentrating suspended solids in water by giving more force to the particles through centrifugal velocity, thus causing the particles to be isolated from the water.


Chemical Oxygen Demand
More...
See "COD."


Chloramines
More...
Chloramines are produced when hypochlorites are mixed with ammonia.  They are sometimes used for disinfection.


 
Chlorination
More...
Chlorination is the destruction of waterborne pathogens through disinfection with various forms of chlorine (e.g. sodium hypochlorite- NaOCl. Calcium hypochlorite-Ca (O Cl2) * 4 H2O, and chlorine gas, chloramines, and chlorine dioxide.  Design of feed facilities for each of these chemicals has been achieved.


Chlorine Dioxide
More...
Chlorine dioxide is a very effective form of chlorination which will kill protozoans,  Cryptosporidium, Giardia, and viruses that other systems may not kill.  In addition, chlorine dioxide oxidizes all metals and organic matter, converting the organic matter to carbon dioxide and water.


 
Clarifier
More...
A clarifier separates or clarifies the settleable solids from treated water to produce a clear supernate.


 
COD
More...
The Chemical Oxygen Demand (COD) is a way of measuring the amount of organic waste in wastewater.  The C.O.D. is the amount of chemically oxidizable materials present in the wastewater.


 
Coliforms
More...
Coliform bacteria are aerobic and facultative anaerobic, non-spore forming, Gram-stain negative rods that ferment lactose with gas production within 48 hours of incubation at 35°C.  Coliforms serve as indicator organisms of contamination of water sources from feces from warm-blooded animals and humans.  There are three techniques for determining the presence of coliform bacteria: fermentation tube, membrane filter, and presence-absence.


 
Color
More...
A physical characteristic describing the appearance of water not to be confused with turbidity.  Color is harmless and is the color after suspended particles have been removed.  The Environmental Protection Agency (EPA) limits color.


 
Comminutor
More...
A comminutor usually follows the grit chamber in a wastewater treatment facility.  The comminutor uses a series of disks to shred objects into smaller pieces.

 

Dechlorination
More...
At the end of the wastewater treatment process, chlorine is added to water to kill pathogens.  After a contact time, the water is then dechlorinated - chemicals are added to the water to destroy the remaining chlorine.  Dechlorination protects the health of the receiving waters into which the treated water is released.  

 

Density
More...
Density is the closeness of materials, calculated as the weight divided by the volume.  

 

Detention Time
More...
Detention time refers specifically to wastewater and is the actual time a portion of influent or effluent is kept in the plant per unit volume.

 
Digester
More...
Sludge from the clarifiers is sent to the digester where the organic matter is digested.  


 
Dilution
More...
Dilution is the mixing of a strong concentration of solution with water or other liquid to produce a weak concentration.  Contact filter media such as rotating biological contactors (RBC) and trickling filters use the concept of dilution in order to avoid biological oxygen demand (BOD) overloading in their treatment processes.

 
Dilution Rates
More...
Dilution rates refer to the amount of effluent mixed with the amount of nonpotable influent especially in trickling filter facilities.

 
Disease
More...
One of the main goals in treating wastewater is to eliminate the spread of waterborne disease.  The coliform test provides a means of documenting the presence of fecal matter, which is a potential source of disease.  Effluents from sewage treatment facilities disinfect by use of chlorine, ultraviolet radiation, and to a small degree, ozone.

 

Disinfection
More...
Disinfection is the final stage in the wastewater treatment process.  During disinfection, all of the pathogenic bacteria are killed.  Water can be disinfected using chlorine, ozone, or ultraviolet light.  

 

Dissolved
More...
Substances which are dissolved in water have become a part of the water solution and cannot be removed from the water by physical means, such as filtering.

 

Diversion Basin
More...
A diversion basin is used to prevent washouts in a treatment plant.  Extra wastewater is held in the diversion basin during heavy rains rather than rushing through the treatment plant.  The wastewater is fed back into the treatment plant at a controlled rate once the influent flows have returned to normal.


DO (Dissolved Oxygen)
More...
DO refers to the amount of dissolved oxygen in water expressed in milligrams per liter.


DO - Controlling
More...
Dissolved oxygen (DO) can be somewhat controlled by physical and mechanical methods.  The DO level in wastewater treatment is crucial to the success of BOD removal and proper sludge formation.  DO can be added by mechanical mixing and air pumps.  Plants can decrease DO levels by reversing aeration methods.


DO - Measuring
More...
Dissolved oxygen (DO) can be measured using a DO meter or using the Winkler method.


Drying Bed
More...
Drying beds are open-air drainage systems for dewatering digested sludge.  The beds are usually covered to prevent excess moisture from slowing the evaporation process and the beds are separated into individual sand-filled beds with gravel and drainage system underneath.

 
Economics
More...
Processes have to be continually monitored to minimize costs.  Alternative methods must also be explored to help keep treatment facilities operating within feasible limits.

   

Efficiency
More...
Efficiency is the act of being adequate in performance with a minimum of waste or effort.

   

Efficiency - Measuring
More...
Efficiency is measured as absolute efficiency or is compared to a standard.

   

Efficiency - Relationship to Energy and Power
More...
Efficiency is closely related to energy and power.  

   

Effluent
More...
The effluent is the end product of wastewater treatment - clean water to be released into receiving streams.

 
Electrolyte
More...
A conducting medium in which the flow of current is accompanied by the movement of matter in the form of ions.  Any substance that dissociates into ions when dissolved in a suitable medium or melted and thus forms a conductor of electricity.

 

Energy
More...
Energy is the capacity for doing work.  

 

Extended Aeration Plants
More...
Extended aeration plants are similar to packaged plants, but with an additional two hour detention time in the aeration chamber.  During this additional two hours, the microorganisms start to die from lack of food and also begin to eat each other.  As a result, the extended aeration plant produces less sludge than a packaged plant does.

 
F/M
More...
In both fixed-film and suspend solids growth systems, activated sludge is returned to the system to maintain a proper balance between the food supply and the mass of microorganisms in the system.  This balance is the food-to-microorganism ratio (F/M) and is important in the removal efficiency.

 

Facultative
More...
Facultative bacteria are able to break down organic matter in the presence and absence of oxygen.  When the oxygen content of water is high, facultative bacteria consume food very quickly using the free oxygen in the water.  In low oxygen concentrations, facultative bacteria are still able to consume organic material, although they do so much more slowly.  

 
Feasibility
More...
Feasibility is the likely hood or probability of an event of process taking place.


Feed Rate
More...
Feed rate refers to the amount of substance (usually in milligrams per liter) needed per unit of time and volume to produced a desired effect or condition.


Fixed Media Filters
More...
Fixed media filters use microorganisms attached to a medium (rocks, plastic, metal, etc.) to break down the BOD and ammonia in wastewater.  Two types of fixed media filters are RBC's and trickling filters.  

 
Flammables
More...
Flammables are any materials or substances that may ignite or burn.  The State Fire Marshall regulates flammable materials and their handling.

 
Food to Microorganism Ratio
More...
See "F/M".

 
Food/Substrate
More...
(Substance acted upon by an enzyme.)  Whatever supplies nourishment to organisms;  any nourishing substance that is eaten, drunk, or otherwise taken into the body to sustain life, provide energy, promote growth, etc.)

 
Grease
More...

 Grease in sewage plants is a major cause of foaming by actinomycetes organisms.  Past problems have led to the installation of grease traps in sinks. 

 

Grinding Pump
More...

"Grinding pump" is another name for a comminutor.  See more under "Comminutor".

 

Grit
More...

Grit is the heaviest material in wastewater and includes substances such as sand, coffee grounds, eggshells, gravel, and cinders.  Grit cannot be broken down by biological processes and would cause a great deal of wear and tear on a treatment facility, so it is removed in the grit chamber and hauled to a landfill.

 

Grit Chamber
More...

The grit chamber follows the bar screen in a typical treatment plant.  The grit chamber removes grit from the wastewater. 

 

Hydraulic Loading
More...
Hydraulic loading is the amount of wastewater applied per day over the surface area of the media.

 

Hypochlorite
More...
Hypochlorite is a liquid form of chlorine used to disinfect water.


   
Identifying Microbes & Optimum Conditions
More...

 Every organism has conditions conducive to growth and replication.  Identifying the organism and determining those conditions are an integral part in maintaining the health of a treatment facility.

 
Kinetics of Growth
More...

 Kinetics of growth refers to optimizing all conditions with respect to the reproduction and growth curve of the range of organisms that perform the treatment process in a wastewater treatment facility.

   

Measurement
More...
 Measurement is a way of quantifying a comparison to a standard.  This must be done with the utmost of accuracy to insure credible results.

   

Mixed Liquor
More...
Mixed liquor is a mixture of raw wastewater and returned sludge.

 
MLSS
More...

 Mixed Liquor Suspended Solids (MLSS) are the amount of total suspended solid material (organic and inorganic) in the mixed liquor sample taken from the oxidation ditch or treatment basin.  Results are found by filtering the mixed liquor through a glass filter and drying the residue in a 105*C oven.  The weight of the filter must be known before the sample is filtered.  The difference between the dried weight of the sample plus filter and the dry filter is the weight of the total suspended solid.

 
MLVSS
More...

 Mixed Liquor Volatile Suspended Solids (MLVSS) are the amount of organic material suspended in the mixed liquor sample taken from the oxidation ditch or treatment basin.  Results are found by filtering the mixed liquor through a glass filter and drying the residue in a 105° C oven.  The weight of the filter and the suspended solids must be known before the sample is placed in a 500° + 50°C muffle furnace and ignited.  The difference between the dried weights is the weight of the organic matter.

 
Moisture
More...

Condensed or diffused liquid, especially water:  moisture in the air.
 
 
NH4OH
More...

 Ammonia (NH4OH) is a major component of urine, cleaning agents, and decaying matter.  In higher organisms such as animals and humans, ammonia is produced as a waste product during protein reduction.  Wastewater treatment facilities monitor ammonia levels in the effluent and are subject to restrictions under various regulatory agencies.  Treatment methods such as oxidation ditches, rotating biological contactors, and trickling filters are especially efficient at converting ammonia into nitrates through the use of older microorganisms.

 
Nocardia (Bad, bad Leroy Brown)
More...

 Nocardia is a bacterium commonly found in water and wastewater, which degrades hydrocarbons (fats) and other complex chained compounds.  Nocardia  is a gram positive filamentous actinomycetes that has branching filaments.  Nocardia are a major cause of foaming in activated sludge plants.

 

NPDES
More...
The National Pollution Discharge Elimination System (NPDES) provides the basis for effluent standards for individual states under the federal direction of the Environmental Protection Agency (EPA) by permit program.  Effluent limits allow discharge of a specified amount of conventional pollutants and either limit or prohibit emission of toxic pollutants.   Effluent parameters monitored by the NPDES include BOD, suspended solids, pH, fecal coliforms, residual chlorine, ammonia nitrogen, and oil and grease.

 

Organic Loading
More...
Organic loading is the amount of B.O.D. applied to the filter per day per volume of filter media. 


 
OSHA
More...

Occupational Safety and Health Administration.  The division of the Department of Labor that sets and enforces occupational health and safety rules.

 
O.U.R.
More...

The Oxygen Uptake Rate (O.U.R.) is the rate at which oxygen is consumed by living organisms in the water.  The O.U.R. of the sludge from the digester is tested to evaluate the condition of the microbes.  The O.U.R. is evaluated by measuring the change in oxygen level over a period of defined time.

 

Overview of Sewage Treatment
More...

Typical treatment of sewage in  a treatment plant includes a bar screen, grit chamber, comminutor, aerator, clarifier, and disinfection.

 
Oxidation Ditch
More...

 An oxidation ditch is a wastewater treatment process that employs free-swimming microbes with forced aeration and activated return sludge to remove BOD and ammonia.

Oxygen Cycle
More...

 Oxygen is cycled through the environment, both  in the air and in the water.

 

Ozone
More...
Ozone consists of three oxygen molecules bound together.  Ozone can be used to disinfect water.  


 
Packaged Plant
More...

  A package plant is particular method of sewage treatment, which involves the use of return activated sludge that is able to reduce BOD in a matter of hours.  Package plants are usually used for small communities and not do use forced air like an extended aeration plant.  Packaged plants are very economical to operate, but produce a large amount of sludge and have poor ammonia removal.

 
pH
More...

 pH is a measure of a weak acid or base.  Strong acids or bases are measured in %, normal or molal.  The pH scale most closely resembles the variance found in nature.

 
Piping
More...

Piping allows conveyance of a fluid from one point to another.

 
Ponds
More...

Ponds can be used to provide primary, secondary, or tertiary sewage treatment.  Ponds have both advantages and disadvantages compared to packaged plants.  

 
Ponds - Requirements
More...

A sewage pond and surrounding area must be planned in such a way that the human and natural environments surrounding the pond are not damaged.      

 
Ponds - Types
More...

Sewage ponds can be divided into several types based on their location in the sewage treatment process and based on the type of respiration occurring within the pond.  

 
Power
More...

Power is the way or system with which energy is harnessed.

 
PPM
More...

 PPM is the abbreviation for parts per million.  A part per million is equal to a milligrams per liter.   Parts per million refers to a ratio of weights.  For example, one part per million is one pound in a million pounds, one ounce in a million ounces, one gram in a million grams, etc.   In water treatment, one part per million is 8.34 pounds in a million gallons in that one gallon weighs 8.34 pounds.

 
Precipitation
More...

The amount of rain, snow, hail, etc., that has fallen at a given place within a given period, usually expressed in inches or centimeters of water.  (In Chemistry, the precipitating of a substance from a solution.)

 
Precision
More...

 Precision refers to the consistency in grouping of results in measurement.

 
Pretreatment
More...

 Pretreatment is the beginning of the wastewater treatment process.  It usually includes screening and shredding the sewage.

 
Primary Treatment
More...

Primary treatment is the part of the wastewater treatment process following pretreatment.  During primary treatment, some of the solid matter settles out of the wastewater.

 
Pumps
More...

 Pumps are mechanical devices that change pressure at a given flow.  Pumps are most efficient at only one pressure and flow and are rated accordingly.

 

RAS
More...

See "Sludge - Returned Activated."

 
RBC

 A Rotating Biological Contactor (RBC) is a wastewater treatment device that uses a large rotating disk to provide a contact media for fixed microbial growth.

Recirculation
More...
Recirculation is treated effluent from a wastewater treatment plant which is piped back to the beginning of the treatment process and added to the raw wastewater.  Recirculating water is a way of reducing the load of organic waste in the water and of increasing the amount of oxygen in the water.  

 
Regulations
More...

 Standards and procedures set by the administrative branch of the government to enforce laws and treaties that protect the environment.  For example, the Environmental Protection Agency and the Clean Water Act establishes limits on pollution from private and public sources.

 
Roots Blowers
More...

 A Roots blower is a positive air blower, which was first designed in 1859, based on the forward motion of fixed quantities of air from an intake, through the housing, and expulsion through an outlet.  Roots blowers are used in pneumatic conveying systems to handle dry bulk materials such as grain or cement.  In sewage treatment plants, centrifugal blowers are replacing roots blowers.

Rotating Biological Contactor
More...

See "RBC."

 
Saturated
More...

A solution is saturated when it contains as much of a substance as it can hold.  

 
SBR
More...

 A Sequencing Batch Reactor (SBR)  is a wastewater treatment technique consisting of an activated sludge system which operates sequentially in time rather than space.  In other words, the steps in the process take place one after another in the same tank.   Usually a multiple tank system is used, thus allowing the incoming flow to be switched to the empty tank while the other is in operation.  In order to keep microorganisms to treat the influent, a SBR is never completely emptied and retains a portion of the settled solids to provide starter microorganisms for the next batch.

 
Secondary Treatment More....

Secondary treatment is the stage in the wastewater treatment process following primary treatment.  Here, biological processes convert the remaining organic matter into a form which is easier to remove from the wastewater.

 
Sedimentation Chamber More....

 A sedimentation chamber is any container in which the velocity is slowed to allow settling to occur. Sedimentation results anytime flow is reduced by restriction of velocity or a change in aeration.

 
Seeding
More...

 Seeding is the process of inoculating the influent with microorganisms for removal of contaminants.

 

Separator
More...

A separator is similar to a clarifier.  See more under "Clarifier."

 
Septic
More...

 Septic pertains to anaerobic conditions and usually refers to septic tanks or holding areas where free oxygen is unavailable and anaerobic bacteria consume BOD and give off hydrogen sulfide gas and methane.  In some collection systems, sewage in held in the lines for a long period of time and pre-aeration is required to strip the influent of toxic volatile gases caused by the anaerobic conditions.
 
 
Septic Tank
More...

 A septic tank is used to detain domestic waters to allow the settling of solids prior to distribution to a leech field for soil absorption.  Septic tanks treat sewage by anaerobic means and are installed primarily for private homes and housing tracts.  Septic tanks have a normal pH of about 7.

 
Settling
More...

 Settling is the process of causing to sink, become compact, or come to rest.  In wastewater treatment, settling refers to causing a liquid to become clear by forming sediments.
     

Sewage
More...

 Sewage is used household water and water-carried solids.  Also known as "wastewater.

 
Sludge
More...

 Sludge is a semisolid material produced during wastewater treatment processes.  Sludge consists of mostly of dead microorganisms and inorganic matter.

 

Sludge - Calculations
More...

It is necessary to calculate the amount of Returned Activated Sludge and Wasted Sludge.

 
Sludge Disposal
More...

 Sludge disposal refers to the removal and discarding of spent (digested) sludge.  The sludge is dried of excess water before being land applied or incinerated.

 
Sludge Lift
More...

 Sludge lift refers to an air operated chamber that lifts the sludge inside a tube and causes the sludge to flow to the front of a package plant.

 

Sludge - Returned Activated
More...

Some sludge is activated and returned to the aeration basin to digest organic matter in the sewage. 

 

Soil Characteristics
More...
It is often necessary to calculate the density, percent moisture, and percent organic matter of soil.  

 
Solubility
More...

 Solubility is the amount of a substance which will dissolve in water.  Solubility is affected by the type of substance and by the temperature of the water.  

 
Special Problems
More...

 Special problems refer to potential for disease, odor, poor quality effluent, power loss, employee discord, equipment failure, and many other unanticipated problems.

 

Specific Gravity
More...
Specific gravity is a way of relating the density of an object to the density of water to determine whether or not the object will float.


 
Stress
More...

 Stress in wastewater treatment refers to the conditioning of microorganisms to produce the most efficient BOD removal possible.  Microorganisms are stressed by withholding food (BOD) for a period of not longer than ten days.


Sulphur Dioxode
More...
 Sulphur dioxide is used to dechlorinate treated wastewater after the chlorine has had sufficient contact time to destroy harmful microorganisms.  The sulphur dioxide removes the remaining chlorine from the water so that the receiving waters will not be harmed.  

 
Supernatant
More...

 Supernatant (overflow) refers to the clear fluid that is removed from the top of tanks and ponds, which has separated from solids during settling.

 
Supersaturated
More...

If a saturated solution is heated, more of the substance can become dissolved in the solution.  If the solution is then cooled, it holds more of the substance than it should be able to hold, so it is supersaturated.


 

Surface Area
More...

The ratio between surface area and mass determines how quickly oxygen will diffuse from air into water and determines how well bacteria can take up oxygen out of water.  

  
Suspended
More...

Substances which are suspended in water are mixed with the water but can be removed by physical means, such as filtering.  

 
Suspension by Air
More...

Settling can be accelerated by use of air in a grit chamber and increased by the reduction of air in a clarifier.

 
Suspension - Velocity of Water
More...

 Suspension velocity is the aggregation of particulate material in a two-step sequential process.

 
SVI
More...

(Sludge Volume Index) Sample of sludge solution from the aeration basin. Watch and view it settling over time (usually 15-20 minutes). Volume decrease of sludge is what is looked at.
 

 

Temperature
More...

 Temperature is a measure of average random energy.

  

Tertiary Treatment
More...

Tertiary treatment is an optional step in the wastewater treatment process, following secondary treatment.  It reduces the nutrient content of wastewater to prevent algae blooms in the body of water into which the effluent will be released.

 
Total Flow
More...

Total flow is the total amount of water flowing through a wastewater treatment plant.  

 
Toxicity Testing
More...

 Toxicity testing involves the study of chemical agents that cause diminished health and death in organisms.  The only valid tests to prove toxicity are conducted on living specimens.  In testing water quality, fat head minnows and clams are most widely used to determine toxicity levels of various components.

 
Toxins
More...

 Toxins are any of a variety of unstable, poisonous compounds produced by some microorganisms that cause certain diseases or physical reactions.

 
Trickling Filter
More...

Trickling filters are a type of fixed media filter. 

 
TSS
More...

 Total Suspended Solids (TSS) refers to the nonfilterable residue that is retained on a glass-fiber disk after filtration of a sample of water or wastewater.

 
Ultraviolet (UV) Light
More...

Ultraviolet, or UV, light is light beyond the violet end of the visible spectrum.  It can be used to disinfect water.  

 
Valves
More...

Valves are mechanical devices that allow or impede the movement of a liquid or a gas.

 
Vector
More...

A vector is a quantity with both distance and direction.

 
Washout
More...

A washout occurs when a great deal of stormwater flows into a treatment plant.  Microorganisms, sludge, and wastewater are pushed through the plant and out into a river or stream before being properly treated

 
Wastewater
More...

 Wastewater is a community's used water and water-carried solids.  This can include storm water and sewage.

 
Wet Well
More...

 A wet well is a compartment or tank in which wastewater is collected.