concentration increased. From these results, it can be estimated that the m-NOEC of
TMAC is 1 mg/L.
7.1.5 Soap
The addition concentration of soap was adjusted to 10, 30, 50, 100, 150, and 200 mg/
L, and it was added on the 16th day of the stable state into the microcosm. Soap
supplied to this experiment was composed of sodium fatty acids (C8–C18). The
endpoint was the population density (structural parameter) measured using an optical
microscope and counted from the start of culturing on days 0, 2, 4, 7, 14, 16, 18, 20,
23, and 30, and it was evaluated from the results of B 16–30 (days 16–30), which was
the ratio of abundance and population density (N 30 ) on the 30th day. Using the
structural parameter, the same density of microorganisms was maintained in the
10 mg/L and 30 mg/L soap addition systems as in the control system. Cyclidium
glaucoma disappeared at concentrations of up to 50 mg/L 2 days after the addition of
soap, but its population slowly recovered 4 days after the addition of soap and was
Fig. 7.3 Time course of P/R ratio in SDS-added microcosm N-system
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K. Murakami et al.