FRODUC
t is apparent that the disposaloofssewage i
marine waters must raise the level of oxidizable or
ganic carbon in the water, but the degree to which the
elis raised, the times of maximum input, and the
sistence of the organic carbon have been unclear.
uch matters are of importance for two reasons: 1) Some
the organic carbon introduced by the sewage is in
irticulate form and invites the attachment and prolif
ration of bacteria; 2) if sewage deposits a great exc
organic carbon, there will be an increased demand or
oxygen for its oxidation and an accompanying stress
aerobic organisms. The objectives of this study have
en consonant with the above considerations. Readily
oxidizable organic carbon was measured by its abilit
to reduce dichromate
IATERTALS AND NETHOD
Oxidizable carbon was determined by the col-
imetric method described by Parsons and Strickland (1
with the following modifications. Three mls. of unfilter
amwe
15X1.5 cm. test tubes and heate
vith one ml.
phosphoric acid in a hot water bath at
00
C for thirty minutes. Then one ml. of sulfuric aci
chromate oxidant was add
to the above,and the solution
was heated as before for an additional sixty minutes. En
tinctions were measured in a l cm. cell in a Beckman DU
at 440 mu. Oxidizable carbon was determined from a standar
curve constructed by measuring the extinctions of various
glucose concentrations. The linearity of this curve made
the following equation applicable:
grams carbon/3 mls= Ex G, where E is the mean
extinction of triplicate determinations and G is the con
stant for a given oxidant solution. In this series o
xperiments two oxidant solutions were used. For the
first of these, G-260, and for the second, G-310. In
general, G- 10 x glucose concentration which yields ar
extinction of .100. Even samples containing fine particu-
late matter gave results within that limit
Biological Oxygen Demand (BOD) was determined by
standard methods (2) with only a three hour incubation
eriod before titration.
namics of organic carbon and BOD were studie
as follows. The samples were well-aerated or maintaine-
under anaerobic conditions by bubbling nitrogen gas
at a similar rate. Incubation was at 14 C, the temperature
of ambient sea water
The preparations were sampled at
intervals for the organic carbon or oxygen determinations
lguresl and 2 compare the rate of decomposition
organic carbon under anaerobic and aerobic conditions
287
Notice that the level of organic carbon, even in th
undiluted sewage, does not greatly exceed the level
carbon in raw sea water. Figure 1 indicates that the rate
f decomposition is fastest at the beginning of the perio
udied, and the initial decomposition rate becomes greater
as the sewage concentration increases. It is apparent from
the second figure that dichromate-oxidizable organic carbon
appears to be generated during incubation under aeration.
gure 3 compiles the data obtained when adsorption
of organic material to surfaces was controled by incubatin
ml. aliquots of sample in the same test tubes later
used for carbon analysis. Results indicate that falling
carbon levels are attributable to genuine decompositior
not simply adsorption
Changes in BOD with time were observed in sewage
iluted to 1/10 and 1/100. See Figure 4
inally, a study was made of the levels of oxidizable
arbon in sewage drawn from the Monterey facility at the
same hours on three consecutive days. Results appear in
igure 5. Apparently there is no predictable cycle
SCUSSTOI
It is important that under aerobic conditions the
vel of organic carbon detectable by dichromate reductior
is unlikely that organic carbon synthesized
scillates.
It
Co, fixation can account for this effect because the
riods of oscillation are too short to be explained or
25.
gges
The periodic ir
microbial growth
dichrom
naterial susceptible
ria
un
organic n
ane
eadi
oxidizabl
the amounts
hard
However
n the environmen
asse
in these materials suggest t
qualitative change
oxygen content of waste waters may
interest that these qualitat

under anaerobic condition
wi.
sewag
dil

that the amoun
mater
crease
oxidation increa:
rob
periodic increa:
increas
hroma
rial indiate
xidizabl
actio
artial oxidatio.
by microbial
anic mater
nore susceptit
an
lation as w.
dation
ichromate ox
ious
utions
at higher
reatment plant
organic carbon
tribution to
onten
water
ampl
maximum
nput of organic car
e
me
environment from the outfall are not predictable
Anaerobes can decompose organic carbon.
4) Under aerobic conditions, organic carbon in se-
water and sewage undergoes qualitative changes making it
resistant to microbial and dichromate oxidation.
S
ONLEDGE
would like to express my appreciatior
lips for his continued guidance an
John
also extende
upervision.
ratitude
ss Elaine Anselmo, who shared some of the incon
venience of late test hours. This work was suppoi
by the Undergraduate Research Program of
par
inal Science Foundation
Grant GY-4369
trickland
and Parsons, T.R. A Manua!
Sea Water Analysis
Ottawa:
Fisheries Research Bo
f Canada, 1965, pp
137-140
Standa:
Methods for the
xamination of Water and Wast
Wate
Vew York: American Public Health Association,
1965, pp. 415-418.
dichromate-oxidizable or
Changes
tter under anaerobic conditions
hanges in dichromate-oxidizabl
rga
tter under aerobic conditions
dichromate-oxidizab.
tter maintained:
Dof sewage under aerobie
itions
Amount of dichromate-oxidizable org
itter in Monterey effluent at inte
three consecutive
bulated numbers are in term
grams of carbon/ml
25

o
40
30
20
50
40
30
20
10
Sewage 1/1
4
Sewage 1/3
11 22
11 22
Ho urs
0
Sewage 1/5
4
Sea Water
4
11 22
11
22
268
9





o
50
40
30
20
50
40
2
g. 2
Sewage 1/1
4
Sewage
4
11 22 26
22 26
Hours
Sewage
4
Sea Water
4
11 22 26
22 26
68
50
30
20
10
0
50
40
30
e
e5
20

.

50
40
20
10
Sea Watet
2 4
6 8 10 12 14 16 18 20 22 24 26 28
Sewage
11/10
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Sewage 1/100
6 8 10 12 14 16 18 20 22 24 26 28
24
Hou rs
266
5
40
30
20
10
00
S

O(
2(
Fig
Sewage 1/10

Sewage 1/100
6
12
16
Hours
67
Body of table gives organic carbon in  grams/ml.
raw sea water ran
ent o
oxidizable car
the period studied
uri
lagrams
om3