TITLE:
Dynamics of Nitrogen Transformation and Removal in a Pilot High Rate Pond
AUTHORS:
Aloyce W. Mayo, Emmanuel E. Hanai
KEYWORDS:
High Rate Ponds, Nitrification, Denitrification, Nitrogen Transformation, Nitrogen Removal
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.6 No.5,
April
21,
2014
ABSTRACT:
The
transformation and removal of nitrogen was studied in a pilot high rate pond
with a surface area of 10.2 m2 and water depth of 60 cm. The pilot
unit received wastewater from an existing field scale primary facultative pond
at the University of Dar es Salaam. Wastewater samples were collected from the
influent and effluent of high rate pond and were analyzed for physical-chemical
parameters in the laboratory and in situ. An appropriate model complexity was selected, from which a conceptual model was
then developed to model various processes in the system using STELLA 6.0.1
software. The study demonstrated that dominant nitrogen transformation
processes in HRP were
nitrification and denitrification, which transformed 0.95 and 0.87 gN/m2·d,
respectively. These were followed by mineralization (0.37 gN/m2·d),
ammonia uptake by microorganisms (0.34 gN/m2·d), volatilization
(0.30 gN/m2·d), sedimentation (0.24 gN/m2·d), and
regeneration (0.15 gN/m2·d). Uptake of nitrate was not observed
because of microorganisms preference for ammonia, which was abundant in the
pond. The major nitrogen transformation mechanisms in high rate pond were
denitrification, net sedimentation and volatilization, which accounted for
69.1%, 7.1% and 23.8% of the total permanent removal mechanisms of nitrogen in
High Rate Pond.