Abstract:
Traditional methods of ammonium removal from
municipal wastewaters rely on
naturally occurring biological processes, where ammonium is converted into less
harmful substances before
being released into the environment. These processes are
extremely effective at nitrogen removal but are less responsive to shock loads, in
which case
they can fall short of achieving the required effluent quality. In recent
years research has been conducted into the possibility of using ion exchange
technology as a complementary process for the. removal of ammonium from
wastewater streams. Much of the research has been concerned with the
.performance
of
naturally occuring materials, zeolites, with much of the work being undertaken at
laboratory scale using synthetic solutions. This study investigates the performance of
the modified
media, MesoLite, using real and synthetic solutions, at both laboratory
and
pilot scale, in the presence of competing cautions. Initial studies were performed
under batch conditions to assess the effect of a number of
parameters such as contact
time, solution ammonium concentration and pH on the uptake of ammonium on to
MesoLite. This was followed
by a investigation into a number of design parameters
under
dynamic conditions, leading to a pilot scale examination of the potential of the
process to be used for the application of removing ammonium from low concentration
wastewater treatment works effluents.
Subsequent experiments were performed pilot
scale to
investigate the benefit of using the ion exchange process for ammonium
removal from
high strength liquors arising from the sludge dewatering process.
Results indicate that a
range of parameters affects the performance of the media and
optimum performance is observed at high ammonium concentrations with increased
contact time at
pH 6-7. Results also show that MesoLite was successful in removing
ammonium from
high concentration sludge liquors, giving a total capacity of 47-51 g
+ -1 + -1
NH4 N kg and a operational capacity of 27 36 g NH4 N kg . The treatment of
low concentration effluents return a total
capacity of 19 g NI-14+-N kg`1 and a
operational capacity of 9.5 g NI-14+-N kg`1. However, this reduced capacity is offset by
the
significant increase run time, from 1.5 to 22 days, and a increase in the amount
of
liquid treated from 140 bed volumes to in excess of 6000 bed volumes.