compared with the 50% and 100% addition systems. The abundance of predatory
micro-animals decreased in the 50% addition system, more than in the 25% addition
system. The abundance of the producers, Chlorella sp., Scenedesmus quadricauda,
and Tolypothrix sp., decreased in the microcosm, and the top predator, Philodina
erythrophthalma, became extinct in the 100% addition system. From these results,
the m-NOEC of the structural parameter was estimated as 25%. As a functional
parameter, the P/R ratio was close to 1 in all microcosm systems. In comparison with
the control system, the system bioactivity (i.e., the value of DO) of the 25% addition
system rose and then decreased before finally stabilizing; that of the 50% addition
system rose and then decreased to 0, and that of the 100% addition system decreased
to 0 immediately after the addition of drainage water. Put succinctly, the bioactivity
of the microcosm increases to maintain itself with low drainage input but cannot rise,
and it collapses with high drainage input. From these findings, the m-NOEC of the
functional parameter was estimated as 25%. Dilution of more than four times was
judged as necessary to discharge this drainage safely (Fig. 9.10).
a)25%
b)50%
c)100%
Respiration(mg O 2 /day)
Production(mg O
2 /day)
18
14
12
10
8
4
2
0
6
20
16
0 2 4 6 8 10
16
12 14
18 20
Respiration(mg O 2 /day)
Production(mg O
2 /day)
0 2 4 6 8 10
16
12 14
18 20
18
14
12
10
8
4
2
0
6
20
16
Respiration(mg O 2 /day)
Production(mg O
2 /day)
0 2 4 6 8 10
16
12 14
18 20
18
14
12
10
8
4
2
0
6
20
16
Fig. 9.10 Time course of P/R ratio in metal processing plant effluent added microcosm-WET test.
(a) 25% (b) 50% (c) 100%
182
Y. Inamori et al.
micro-animals decreased in the 50% addition system, more than in the 25% addition
system. The abundance of the producers, Chlorella sp., Scenedesmus quadricauda,
and Tolypothrix sp., decreased in the microcosm, and the top predator, Philodina
erythrophthalma, became extinct in the 100% addition system. From these results,
the m-NOEC of the structural parameter was estimated as 25%. As a functional
parameter, the P/R ratio was close to 1 in all microcosm systems. In comparison with
the control system, the system bioactivity (i.e., the value of DO) of the 25% addition
system rose and then decreased before finally stabilizing; that of the 50% addition
system rose and then decreased to 0, and that of the 100% addition system decreased
to 0 immediately after the addition of drainage water. Put succinctly, the bioactivity
of the microcosm increases to maintain itself with low drainage input but cannot rise,
and it collapses with high drainage input. From these findings, the m-NOEC of the
functional parameter was estimated as 25%. Dilution of more than four times was
judged as necessary to discharge this drainage safely (Fig. 9.10).
a)25%
b)50%
c)100%
Respiration(mg O 2 /day)
Production(mg O
2 /day)
18
14
12
10
8
4
2
0
6
20
16
0 2 4 6 8 10
16
12 14
18 20
Respiration(mg O 2 /day)
Production(mg O
2 /day)
0 2 4 6 8 10
16
12 14
18 20
18
14
12
10
8
4
2
0
6
20
16
Respiration(mg O 2 /day)
Production(mg O
2 /day)
0 2 4 6 8 10
16
12 14
18 20
18
14
12
10
8
4
2
0
6
20
16
Fig. 9.10 Time course of P/R ratio in metal processing plant effluent added microcosm-WET test.
(a) 25% (b) 50% (c) 100%
182
Y. Inamori et al.