The DOC concentration (Fig. 1(d)) remained below 125 mg/L at
29–99 mg/L TN, while DOC concentrations in the RN175 and
RN245 tests were 231 and 340 mg/L, respectively. The concentration
of DOC was steady for some time prior to a gradual increase.
This increase in DOC occurred during the growing process, when
C.vulgaris produces extracellular polymer substances that cannot
be degraded by C.vulgaris (Babel et al., 2002; Paralkar and Edzwald,
1996). The highest removal rate was 0.059 mg DOC/(mg N d), at
246 mg/L TN (Table 3).