classified, it was classified as being in a state of system collapse with 80% sewagetreated plant drainage and a system transition with 40% and 20% sewage-treated
plant drainage. Additionally, when diluted to 20%, it was nearly identical to the
control system. The sewage derived from plant drainage was demonstrated to have a
substantial effect on the microcosm. The influence of sewage-treated water from
domestic or plant drainage on the microcosm was also clearly confirmed from the
appearance of the microcosm during the culturing process. For sewage-treated water,
the substances that may be influenced by precise values of heavy metals and other
chemicals were analyzed, and it was suggested that copper, nickel, and
chlorothalonil may influence the added substances (Fig. 9.5).
9.3.3 Rice-Washed Effluent
A large amount of nitrogen and phosphorus are included in cleansed rice drainage.
These are causative agents of eutrophy and lead to red tides and blue tides—
Respiration(mg O 2 /day)
Production(mg O
2 /day)
0
30
25
20
15
10
5
0
5
10
15
20
25
30
0
30
25
20
15
10
5
0
5
10
15
20
25
30
0
30
25
20
15
10
5
0
5
10
15
20
25
30
0
30
25
20
15
10
5
0
5
10
15
20
25
30
control
20%
40%
80%
Fig. 9.5 Time course of P/R ratio in sewage-treated plant drainage added microcosm
174
Y. Inamori et al.