The pH values recorded in 2009 were higher than those
recorded in 2012. The outlet pH values of the maturation pond 6
were generally higher than the outlet of the CW in the data
recorded in 2009. The pH in the effluent of the maturation pond
6 ranged from 7.42 to 8.38 while that of the effluent of the CW ranged
from 7.41 to 7.74. The increase in pH in maturation ponds was
expected because in this shallow pond algae blooms tend to
remove CO2 from water during the day for use in photosynthesis
and release O2. This increases pH as the carbonate-bicarbonate
equilibrium is destabilised (Mashauri et al., 2000). This difference
between maturation 6 and CW were not observed in 2012 as the
outlet pH values from maturation 6 and CW did not differ much.