Page 754 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Biological Reactions and Kinetics 709

nor other specialized organelles. Compare with
C 5 H 7 O 2 N þ 5O 2 ! 5CO 2 þ 2H 2 O þ NH 3
113 160 eukaryote (Apple Corporation, 2005).
COD(cell) ¼ 160=113 ¼ 1.42 mg COD=mg cells Archaebacteria: Microorganisms that are similar to
bacteria in size and simplicity of structure but rad-
Foregoing from Gaudy and Gaudy (1980, p. 59). ically different in molecular organization. They are
(2) The empirical cell formula, C 5 H 7 O 2 N, was given now believed to constitute an ancient intermediate
initially by Porges et al. (1956, p. 41), with MW group between the bacteria and eukaryotes. Also
(C 5 H 7 O 2 N) ¼ 113 g=mol; when ash was included called archaea (Apple Corporation, 2005).
they gave MW(C 5 H 7 O 2 N þ ash) ¼ 124 g=mol. (3) Biomass: Cell mass.
A cell formula that includes N and P is Biosynthesis: The conversion of substrate to cells. Such con-
C 60 H 87 O 23 N 12 P (Sherrard, 1973, p. 1973). version utilizes ATP, which is converted to ADP in
Benzene ring: (1) A six-carbon ring that provides the struc- the biosynthesis.
ture for a multitude of compounds called ‘‘aro- BNR: Acronym for biological nutrient removal, which refers
matic.’’ (2) Benzene, C 6 H 6 , is the ‘‘parent’’ to nitrogen and phosphorous. Although considered
compound of the aromatic group (Sawyer and since the 1950s, the technologies for nitrogen and
McCarty, 1967, p. 119). phosphorous removals emerged in practice during
Biochemical oxygen demand (BOD): The quantity of oxy- the 1980s.
gen used in the biological oxidation of organic mat- BOD: Biological oxygen demand, which is understood, as a
ter in a specified time, at a specified temperature, and rule, to mean the 5-day BOD.
under specified conditions (URS, 1973, p. K-1). The BOD 5 : A 5-day biological oxygen demand based on a stand-
parameter is measured by a specified procedure. ard laboratory test in which the oxygen concentration
A sample is placed in several 300 mL BOD bottles, in a BOD bottle is determined at t ¼ 0 and again at
all previously aerated. The dissolved oxygen is t ¼ 5 day after incubation at T ¼ 208C. The BOD 5
measured in 1–3 bottles and the others are incubated value is considered as being due to carbonaceous
at T ¼ 208C for 5 days. After 5 days the dissolved- oxygen demand.
oxygen concentrations are measured in the incubated BOD(ultimate): Ultimate biological oxygen demand. The
bottles. From the initial dissolved-oxygen concentra- BOD test is extended to 20 days. The BOD(ultimate)
tion and the final, the 5 day BOD is calculated. For value is considered as being due to the sum of
reference, the BOD test had been in use from some carbonaceous oxygen demand and nitrogenous oxy-
years when it was described by Metcalf and Eddy gen demand.
(1916, pp. 63–69). Bulking sludge: Sludge that is difficult to settle due to an
Biochemical pathway: A complex sequence of reactions that excess of filamentous organisms or excess water.
degrade an organic molecule to certain end products. Carbohydrate: (1) A class of compounds with the general
Examples include the citric acid cycle, also called the formula, C n (H 2 O) n but which applies only to simple
Krebs cycle or the TCA cycle. sugars, called monosaccharides (Campbell, 1991,
Biological oxidation: The process whereby organisms in the p. 72). (2) Polymers built of repeating sugar mol-
presence of oxygen convert organic matter to carbon ecules; glucose is the most common sugar
dioxide and new microorganisms (URS, 1973, p. K-1). (Campbell, 1991, p. 69). See also glucose.
Biological process: (1) A biochemical reaction process that Carboxyl group: An acidic carboxyl group is –COOH
utilizes organisms to convert a given ‘‘substrate’’ to (Rawn, 1989, p. 52).
desired end products, such as new cells, carbon Catabolism: (1) The spontaneous conversion of reactants,
dioxide, water. If the reaction is anoxic, i.e., ‘‘with- e.g., proteins, polysaccharides, lipids to products.
out oxygen,’’ the substrate may be ammonia, nitrite, (2) An example of such conversion by aerobic
or nitrate, with end products, nitrate, nitrite, and means is given by Rawn (1989, p. 243), who
nitrogen, respectively. If the reaction is anaerobic, shows three stages: (a) starting with proteins, poly-
the substrate is an organic compound that is con- saccharides, lipids, hydrolysis occurs to give amino
verted to carbon dioxide and methane. acids, mono and disaccharides, and fatty acids and
Biological terms glycerol, respectively; (b) the foregoing products are
Eukaryote: An organism consisting of a cell or cells converted by glycolysis to pyruvate and then to
in which the genetic material is DNA in the form acetyl CoA giving off an ATP; (c) the acetyl CoA
of chromosomes contained within a distinct feeds into the citric acid cycle and is oxidized to give
nucleus. Eukaryotes include all living organisms NADH, with products, ATP and NAD, and water.
other than the eubacteria and archaebacteria. Com- Other products, from Stage (a) are NH 3 (from amino
pare with prokaryote (Apple Corporation, 2005). acids), and carbon dioxide from Stage (b) and Stage
Prokaryote: A microscopic single-celled organism, (c). As contrasted to biosynthesis, catabolic path-
including the bacteria and cyanobacteria, which ways result in few end products (Rawn, 1989,
has neither a distinct nucleus with a membrane p. 262). (3) A simple definition: the breakdown of