Introduction
Nitrogen is causing eutrophication of water bodies worldwide
and domestic wastewater is among the major sources of nitrogen
disposal into the environment (de Godos et al., 2010). The major
effects of nitrogen pollution are manifested in eutrophication of
surface waters as well as pollution of ground water. Algal blooms
and proliferation of non desired aquatic weeds have been associated
with nutrient pollution (Bolan et al., 2009). Indirect effects
of nitrogen pollution range from the blue baby syndrome to fish
kills, from loss of aesthetic values of water to increased costs of
water treatment. The possibility of nitrous greenhouse gas emissions
from polluted water bodies has also been suggested (Gijzen
and Mulder, 2001; Martinez et al., 2009).
Many nations have adopted stringent effluent nitrogen standards,
which is associated with increased treatment costs and
demands upgrading of the already existing wastewater treatment
(WWT) systems or construction of new systems. Simple and cost
effective systems like wastewater stabilization ponds (WSP) in
the standard configurations will in most cases not meet discharge
standards. WSP research has shown large variations in performance
for nitrogen removal, but it remains unclear which mechanisms are
responsible for nitrogen removal under varying environmental