478
O.D. Brockett and P. Welsby
(a)SUMMER
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6
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10 HOURS 14 16 18 20 22 24
(
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6
8
10 HOUR
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—
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4S14
16 18 20 22 24
| |
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1
1
S14 16 18 20 22 24
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6
8
10HOURS14 16
18 20 22 24
-
6
8
10 RΦURS 1
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j Ί
4" 16
â
2 0 22
24
I
|
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l
2
4
6
8
10 HOURS 14 16 18 20 22 24
Fig. 2.
continous degradation of organic matter, which is shown by the production of methane,
carbon dioxide and nitrogen, as well as the generation of nutrients for metabolism by the
biomass at the sludge/water interface and the above pond liquor.
Redox Potential pf the sludge/liquor Interface
Measurements of redox potential of this region in both summer and winter periods are
shown in Fig. 3 (a) and (b), although electro-positive plateaux occur these are of much
shorter duration than in pond liquor. As before, there was a tendency for this zone to
become more electropositive in summer than in winter. The difference between
electronegative potentials developed in summer and winter is of the order of 120 mV.
The interface has a negative potential for periods at least twice as long as pond top liquor,
thus this region would favour anaerobic growth. The short positive intervals found,
particularly in summer, would allow limited activity of aerobic microorganisms" provided
they could withstand long anaerobic periods.
Redox Potential of Oxidation Pond Top Liquor
Fig. 4 (a) and (b) shows typical curves for summer and winter periods of redox
potential values 10-15 cm. below the surface. In both cases a diurnal pattern is well
established with oxidation pond top liquor being positive for longer periods in the
summer. At the same time there was a shift from more electronegative potentials (approx.
-320 mV) in winter to less electronegative potentials (approx. -190 mV) in summer.
The difference was similar to that found at the interface. In general oxidation pond top
liquor developed electronegative potentials in the late evening which lasted until about
O.D. Brockett and P. Welsby
(a)SUMMER
o-±\
2
4
6
β
10 HOURS 14 16 18 20 22 24
(
o - ±
o - i
o - i
0—
t>) V
' '
'
'
"
m
_
t
i
*T EF
l
ι
4
>
A
2
A
\
\
6
-_.
I
I
| t
- - H -
| _i
1 1
^ 10 HO
|
JR1
6
8
10 HOUR
|
|
I
-L4 J—
—
i i l l
4S14
16 18 20 22 24
| |
I I '
1
1
S14 16 18 20 22 24
-' I -
1
Ί
\
6
8
10HOURS14 16
18 20 22 24
-
6
8
10 RΦURS 1
I
j Ί
4" 16
â
2 0 22
24
I
|
I
Π
l
2
4
6
8
10 HOURS 14 16 18 20 22 24
Fig. 2.
continous degradation of organic matter, which is shown by the production of methane,
carbon dioxide and nitrogen, as well as the generation of nutrients for metabolism by the
biomass at the sludge/water interface and the above pond liquor.
Redox Potential pf the sludge/liquor Interface
Measurements of redox potential of this region in both summer and winter periods are
shown in Fig. 3 (a) and (b), although electro-positive plateaux occur these are of much
shorter duration than in pond liquor. As before, there was a tendency for this zone to
become more electropositive in summer than in winter. The difference between
electronegative potentials developed in summer and winter is of the order of 120 mV.
The interface has a negative potential for periods at least twice as long as pond top liquor,
thus this region would favour anaerobic growth. The short positive intervals found,
particularly in summer, would allow limited activity of aerobic microorganisms" provided
they could withstand long anaerobic periods.
Redox Potential of Oxidation Pond Top Liquor
Fig. 4 (a) and (b) shows typical curves for summer and winter periods of redox
potential values 10-15 cm. below the surface. In both cases a diurnal pattern is well
established with oxidation pond top liquor being positive for longer periods in the
summer. At the same time there was a shift from more electronegative potentials (approx.
-320 mV) in winter to less electronegative potentials (approx. -190 mV) in summer.
The difference was similar to that found at the interface. In general oxidation pond top
liquor developed electronegative potentials in the late evening which lasted until about