EP 1110-1-27
27 Jan 00
(l) Depositional biofouling -- biofouling resulting in the deposition of slime, metal oxide, and other
material on a surface or in a porous medium (bioaccumulation).
(m) Disinfection -- the act of destroying by chemical and/or physical means microorganisms that are
causing an undesirable infestation at a site. It does not mean that all microorganisms are killed; it means
that there is a selective action.
(n) Encrustation -- a relatively solid plate-like or crystalline structure coating a surface. It appears to be
chemical in nature due to the hardness of the structure. Often brittle (when dry) or plastic (when wet), the
organic content is usually relatively small.
(o) Extracellular polymer substances (EPS or ECPS) -- a general term for exopolymers produced by many
microorganisms, typical carbohydrate based, outside the cell (equivalent term, glycocalyx).
(p) Heterotrophic microorganisms -- those microbes which obtain their energy from the breaking down of
organic (carbon-containing) material. Some of these microbes are very specialized (e.g., cellulose
degraders) while others can utilize a variety of organic compounds.
(q) Iron oxidizing bacteria (IOB) -- those bacteria able to oxidize iron by any means from a reduced form
of iron (ferrous form) to an oxidized (ferric) state. Some authorities define genuine IOB as those
chemolithotrophs that oxidize iron metabolically.
(r) Iron reducing bacteria -- those bacteria which are able to reduce iron by any means from an oxidized
form (ferric) to a reduced (ferrous) state.
(s) Iron related bacteria (IRB) -- all of those bacteria which are able to accumulate iron in another form
beyond that for basic metabolic functioning. These accumulated iron compounds generally collect within
the slime (EPS) around the cells and gradually harden (crystallize) over time.
(t) Maintenance monitoring -- as part of a preventive maintenance strategy, monitoring of system
parameters to detect indicators of deteriorating conditions.
(u) Maintenance treatment -- a cleaning treatment applied in a preventive or proactive manner, typically
before performance of the system is impaired.
(v) Microbially induced corrosion -- see Biofouling.
(w) Preventive Maintenance (PM) -- a management strategy of ongoing monitoring and preventive repair
and replacement of components of a system or process to prevent or delay recognized deterioration.
(x) Rehabilitation -- the returning of a well or other system to its original specified state by the application
of suitable treatments.
(y) Redox (Eh) -- oxidation-reduction potential (ORP). Oxidation and reduction reactions mediate the
behavior of many chemical constituents in the environment. This is a relative scale of the intensity of
electron donor activity, as measured between a suitable reference electrode and an inert indicator
electrode, and typically expressed in terms of Eh volts or millivolts (plus or minus) in relation to the
reference.
(z)Redox fringe -- a term applied to transition zones that develop in formations around working wells
where the predominant ion state of metal changes from the reduced, dissolved form (e.g., MnII, FeII) to
B-2
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