Glossary of Terms


  • Activated Sludge

    A wastewater treatment process that uses suspended microorganisms to digest the organic contents of wastewater.
  • Advanced Wastewater Treatment (AVT)

    This is the level of treatment required by the year 2010 for all WWTPs in the Keys with capacities of .0100 MGD or greater. This corresponds to levels of 5mg/L CBOD 5 mg/L TSS, 3 mg/L TN, and 1 mg/L TP.
  • Alternative onsite system

    An onsit treatment system other than a conventional septic tank and leach field design. Alternative systems are used to accommodate a variety of site conditions (e.g., high ground water, low-permeability soil) and/or to provide additional treatment. Examples of alternative systems include alternative collection sewers, sand mounds, sand filters, anaerobic filters, disinfection systems, and cluster systems, among others, as described in “Descriptions of Wastewater Systems”.
  • Alternative Sewers

    Low-cost wastewater collection systems for small communities and/or areas with difficult topography or high ground water or bedrock. Alternative sewers are smaller in size than conventional sewers and are installed at shallower depth, providing a more cost-effective method of wastewater collection. The three main classes of alternative sewers are pressure sewers, small diameter gravity sewers, and vacuum sewers.
  • Best Achievable Treatment (BAT)

    This is the level of treatment required by the year 2010 for all wastewater treatment systems in the Keys with capacities of less than 0.100 MGD, including on-site treatment units. This corresponds to levels of 10 mg/L CBOD, 10 mg/L TSS, 10 mg/L TN, and 1 mg/L TP.
  • Black Water

    Wastewater from the toilet, which contains most of the nitrogen in sewage.
  • BOD

    Biochemical Oxygen Demand (BOD) is the measure of the amount of oxygen required by bacteria for stabilizing material that can be decomposed under aerobic conditions. BOD is a commonly used determinant of the organic strength of a waste.
  • CBOD

    Carbonaceous Biochemical Oxygen Demand. This is a measurement of the level of organic pollutants (food) in wastewater.
  • Centralized System

    A collection and treatment system containing collection sewers and a centralized treatment facility. Centralized systems are used to collect and treat large volumes of wastewater. The collection system typically requires large-diameter deep pipes, major excavation, and frequent manhole access. At the treatment facility, the wastewater is treated to standards required for discharge to a surface water body. The large amounts of biosolids (sludge) generated in treatment are treated and either land applied, placed on a surface disposal site, or incinerated.
  • Class V Well

    A shallow waste disposal well, stormwater and agriculture drainage system, or other device, including a large domestic onsite wastewater system, that is used to release fluids above or into underground sources of drinking water. EPA permits these wells to inject wastes provided they meet certain requirements and do not endanger underground sources of drinking water.
  • Cluster System

    A decentralized wastewater collection and treatment system where two or more dwellings, but less than an entire community, is served. The wastewater from several homes often is pretreated onsite by individual septic tanks before being transported through alternative sewers to an offsite nearby treatment unit that is relatively simple to operate and maintain than centralized systems.
  • Computerized Maintenance Management System (CMMS)

    This is a program that schedules and tracks preventive and corrective maintenance tasks and tracks inventory and costs.
  • Conventional Onsite System

    A conventional onsite system includes a septic tank and a leach field.
  • Decentralized System

    An onsite or cluster wastewater system that is used to treat and dispose of relatively small volumes of wastewater, generally from dwellings and businesses that are located relatively close together. Onsite and cluster systems are also commonly used in combination.
  • Effluent

    Partially or fully treated wastewater flowing from a treatment unit or facility.
  • Eutrophication

    A process by which nutrient-rich surface water or ground water contributes to stagnant, oxygen-poor surface-water environments which may be detrimental to aquatic life.
  • Facultative Pond

    A lagoon that is sufficiently deep (i.e., 5 to 6 feet) where organic solids settle to the bottom as sludge and decay anaerobically; a liquid layer forms above the sludge where facultative and aerobic bacteria oxidize the incoming organics and products of anaerobic sludge decomposition.
  • Fecal Coliform Bacteria

    Common, harmless forms of bacteria that are normal constituents of human intestines and found in human waste and in wastewater. Fecal coliform bacteria counts are used as an indicator of presence of pathogenic microbes.
  • FDEP

    Florida Department of Environmental Protection Agency.
  • FKAA

    Florida Keys Aqueduct Authority.
  • GPD

    Gallons Per Day
  • Gray Water

    Non-toilet household wastewater (e.g., from sinks, showers, etc.).
  • I&I

    Inflow and Infiltration. Inflow is non-sewage water, typically rain water that enters a sanitary sewer system through lids on structures such as manholes. Infiltration is non-sewage water, typically groundwater or rainwater that has soaked into the ground that enters a sanitary sewer system through cracks and joints in buried pipes and structures.
  • Leaching Field

    See “Subsurface Soil Absorption Field”.
  • Management of Decentralized Systems

    The centralized management and monitoring of onsite or cluster wastewater systems, including, but not limited to, planning, construction, operation, maintenance, and financing programs.
  • MGD

    Million Gallons per Day
  • mg/L: miligrams per liter (equal to parts per million)

    This is the unit of measure typically used to report the concentration of pollutants in wastewater.
  • National Pollutant Discharge Elimination System (NPDES)

    A regulatory system that requires wastewater treatment systems discharging into surface waters to obtain a permit from the EPA which specifies effluent quality.
  • Nonpoint Source Discharges

    Relatively diffuse contamination originating from many small sources whose locations may be poorly defined. Onsite wastewater systems are one type of Nonpoint source discharge.
  • Onsite System

    A natural system or mechanical device used to collect, treat, and discharge or reclaim wastewater from an individual dwelling without the use of community-wide sewers or a centralized treatment facility. A conventional onsite system includes a septic tank and a leach field. Other alternative types of onsite systems include at-grade systems, mound systems, sand filters and small aerobic units.
  • Package Plant

    Prefabricated treatment units that can serve apartment buildings, condominiums, office complexes, and up to a few hundred homes. Package plants generally are used as cluster systems, but can also be used in an onsite wastewater treatment train. They are usually of the activated sludge or trickling filter type, and require skilled maintenance programs.
  • Point Source Discharges

    Contamination from discrete locations, such as a centralized wastewater treatment facility or a factory.
  • Pressure Sewers

    An alternative wastewater collection system in which household wastewater is pretreated by a septic tank or grinder and pumped through small plastic sewer pipes buried at shallow depths to either a conventional gravity sewer or a treatment system. Pressure sewers are used in areas with high groundwater or bedrock, low population density, or unfavorable terrain for gravity sewer collection. They require smaller pipes and less excavation than conventional sewers. Two types of pressure sewers include:
  • Septic Tank Effluent Pump (STEP)

    A submersible pump located either in a separate chamber within a septic tank or in a pumping chamber outside the tank pumps the settled liquid through the collector main. Because the wastewater is treated in a septic tank, the treatment facility may be smaller and simpler than would otherwise be needed.
  • Grinder Pump

    Household wastes flow by gravity directly into a prefabricated chamber located either in the basement of a house or outside the foundation wall. The chamber contains a pumping unit with grinder blades that shred the solids in the wastewater to a size that can pass through the malldiameter pressure sewers.
  • Pumping Stations

    A pumping facility is used to lift wastewater where topography is too flat or hilly to permit natural gravity flow to treatment facility.
  • Receiving Water

    Streams (i.e., surface water bodies) into which treated wastewater is discharged.
  • Residuals

    The by-products of wastewater treatment processes, including sludge and septage.
  • ROW

    Publicly owned Right of Way.
  • Secondary Treatment

    Typical effluent quality achieved by a conventional centralized treatment facility, typically defined as 85% reduction of influent BOD and TSS or 30 mg/l or both; which ever is least.
  • Septage

    The solid and semi-solid material resulting from onsite wastewater pretreatment in a septic tank, which must be pumped, hauled, treated, and disposed of properly.
  • Sludge

    The primarily organic solid or semi-solid product of wastewater treatment processes. The term sewage sludge is generally used to describe residuals from centralized wastewater treatment, while the term septage is used to describe the residuals from septic tanks.
  • Small-Diameter Gravity Sewers

    An alternative wastewater collection system consisting of smalldiameter collection pipes (e.g., between three and six inches) that transport liquid from a septic tank to a treatment unit, utilizing differences in elevation between upstream connections and the downstream terminus to achieve gravity flow.
  • SRF

    State Revolving Fund. A source of low-interest loans for utility planning and construction.
  • SSOCOF

    Sunshine State One Call of Florida. The state agency that coordinates underground utility construction. Anyone who intends to dig must call SSOCOF to request locates. SSOCOF then relays the construction information to all members in the construction area with instructions to mark the location of their underground utilities in the work area prior to the start of construction.
  • Subsurface Soil Absorption Field

    A subsurface land area with relatively permeable soil designed to receive pretreated wastewater from a septic tank or intermediate treatment unit (e.g., sand filter). The soil further treats the wastewater by filtration, sorption, and microbiological degradation before the water is discharged to ground water.
  • Trickling Filter

    A fixed-film (see “Fixed Growth Systems” in “Description” section below) biological wastewater treatment process used for aerobic treatment and nitrification.
  • Total Nitrogen (TN)

    This is a measurement of the level of nitrogenous pollutants in wastewater.
  • Total Phosphorus (TP)

    THis is a measurement of the level of phosphate and organic phosphorus pollutants in wastewater.
  • Total Suspended Solids (TSS)

    A measure of the amount of suspended solids found in wastewater effluent.
  • Vacuum Sewers

    An alternative wastewater collection system that uses vacuum to convey household wastewater from each connection to a vacuum station which includes a collection tank and vaccum pumps. Wastewater is then pumped to a treatment facility or conventional sewer interceptor.
  • WWTP

    Wastewater Treatment Plant