Page 761 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

716 Fundamentals of Water Treatment Unit Processes: Physical, Chemical, and Biological

Review, Pollution Engineering, January 1, 1992, (Rawn, 1989, p. 314). (2) The carbon skeleton of
pp. 30, 32 and lists 105 water pollutants for which pyruvate is incorporated into alanine, valine, and
EPA had set numeric limits). leucine, which are known as the pyruvate family of
Prokaryotae: A kingdom comprising all the prokaryotic amino acids (Rawn, 1989, p. 603).
microorganisms (those lacking a true membrane- Recirculation rate: The recirculation of a fraction of settled
enclosed nuclei) (Prescott et al., 1993, p. G-20). activated sludge in the ‘‘final’’ settling tank; the other
Prokaryotic cell: Cells that lack a true membrane-enclosed fraction is ‘‘wasted,’’ also called, ‘‘return activated
nucleus; bacteria are prokaryotic and have their sludge,’’ or ‘‘RAS,’’ the latter having emerged since
genetic material located in a nucleoid. For reference, the 1990s.
other groupings are archaeobacteria and eukaryotic Reduction: (1) Compound that is reduced and gains elec-
(Prescott et al., 1993, p. G-20). trons; oxygen is the best-known example. (2) When
Prokaryotes: Kingdom that includes Bacteria and the an organic compound is reduced biochemically, it
Archaea (Rittman and McCarty, 2001, p. 6). usually gains electrons in the form of hydrogen
They note that little is gained by the division into atoms; consequently, reduction is synonymous with
the two groups; the Bacteria convert complex hydrogenation (Bailey and Ollis, 1977, p. 230).
organic matter into acetic acid and hydrogen and An example is the reduction of pyruvic acid to
the Archaea convert acetic acid and hydrogen into lactic acid when the former gains electrons, i.e.,
methane gas. The latter group, in the past, has been hydrogen atoms, i.e.,
called simply, ‘‘methane bacteria.’’ As a matter of
interest blue-green algae have no nucleus, a property
of bacteria, not of plants, and are classified as CH 3 CH 3
cyanobacteria. j j
C ¼¼ O þ 2H ! CHOH
Prokaryotic cells: Single-celled organisms with nuclear
material loosely organized; examples include j j
COOH COOH
bacteria and cyanobacteria (blue-green algae).
pyruvic acid lactic acid
Eukaryotes, on the other hand, have a true nucleus,
set off from the rest of the cell by a membrane;
Refractory: Refers to any substance that passes through a
examples include plant and animal cells (Campbell,
treatment process (Anon., 1965, p. iii). Chloride
1991, p. 26).
ion is an example. Synthetic organic chemicals are
Protein: (1) All proteins are polymers of a-amino
common.
acids joined by peptide bonds. The length of the
Respiration: (1) The uptake of oxygen by cells. (2) An
polymer varies so that the molecular weight varies
energy-yielding process in which an electron donor
from a few thousand to several million. All proteins
contain about 0.16 fraction nitrogen. Proteins com- is oxidized using an inorganic electron acceptor; the
prise different combinations of the amino acids; the electron acceptor may be either oxygen (aerobic
possible sequences of amino acids number over 10 18 respiration) or another inorganic acceptor (anaerobic
(assuming 20 different amino acids). Protein respiration) (Prescott et al., 1993, p. G21). (3) An
molecules have a primary structure, a ‘‘backbone,’’ energy-producing process in which organic or
and also a secondary, tertiary, and quaternary reduced inorganic compounds are oxidized by inor-
structure, with a ‘‘conformal’’ three-dimensional ganic compounds. When the oxidant is something
structure; each protein has a specific spatial shape. other than oxygen, the process is termed anaerobic
Denaturing a protein causes a change in such respiration (Bailey and Ollis, 1977, p. 241). It is also
molecular structure (Gaudy and Gaudy, 1980, called an anoxic process.
p. 99–115). (2) All organisms, from bacteria to Aerobic respiration: In the oxidation of an organic
buffalo, have proteins made of the same set of 20 compound, oxygen is the final electron acceptor
amino acids (Rawn, 1989, p. 52). (Prescott et al., 1993, p. 134).
Protozoa: Single-celled organisms that can pursue and digest Ribosome: RNA protein particles that contain the enzymes
their food (Rittman and McCarty, 2001, p. 31). They for protein synthesis (Rittman and McCarty, 2001,
form a part of the ecology of biological treatment p. 11).
systems. Rotating biological contactor (RBC): See attached growth
Psychrophile: A microorganism that grows well at 08C reactor. Descriptions and a design protocols are given
and has an optimum growth rate at 158C with a by Tchobanoglous and Burton (1991, pp. 628–636)
maximum of about 208C (Prescott et al., 1993, and by Grady et al. (1999, pp. 907–947).
p. G21). Rotifer: (1) An organism of the class Rotifera, which are
Pyruvate: (1) Pyruvate is a metabolic intermediate; under multicellular, strictly aerobic, and ingest small par-
aerobic conditions, pyruvate is further oxidized by ticulate matter, such as bacteria and algae, and other
the citric acid cycle and NAD is again regenerated living or dead organic matter of similar size