There was a positive relationship between the cell density of
C.vulgaris and NHþ4
–N at below 148 mg/L NHþ4
–N (Fig. 3(e)). The algal
concentration peaked at 2.12 g/L at 148 mg/L NHþ4
–N. Cell density
of C.vulgaris sharply decreased to 1.62 g/L at 194 mg/L NHþ4
–N.
Initial pH in wastewaters was in the range of 9.0–9.3, but later
fluctuated between 6.5 and 7.5 (data in supplemental materials).
The decrease of pH in the first day was regarded as a consequence
of balance of CO2 in wastewater. Our finding is different from that
of Liang et al. (2013) who observed that the pH of single algae
culture was kept increasing over testing time. The reasons
accounting for this inconsistency may be attributable to the higher
buffer capacity of sterilized wastewater than that of artificial
wastewater.