New Zealand Journal of Agricultural Research abstracts
Ammonium removal from wastewaters using natural
New Zealand zeolites
M. L. NGUYEN
C. C. TANNER
National Institute of Water & Atmospheric Research Ltd
P. O. Box 11 115
Hamilton, New Zealand
Abstract Ammoniacal nitrogen (ammonia and ammonium) in
agricultural wastewaters can promote eutrophication of receiving waters and be
potentially toxic to fish and other aquatic life. Zeolites, which are hydrated
aluminum-silicate minerals, have an affinity for ammonium ions
(NH4+) and are, therefore, potentially useful in removing this
contaminant from wastewaters. The major objectives of this study were to
evaluate the capacity of two natural New Zealand zeolites (clinoptilolite and
mordenite) to remove NH4+ from a range of wastewaters under both
batch and flow-through conditions. Effects of two zeolite particle size ranges
(0.25-0.50 mm and 2.0-2.83 mm) on NH4+ removal performance were also
investigated. Results obtained from the batch adsorption experiments indicated
that both zeolites tested, regardless of their particle sizes, were equally
effective (87-98%) at NH4+ removal from domestic wastewaters or
synthetic solutions containing NH4+ concentrations of up to 150 g
NH4-N m-3. However, mordenite showed more effective NH4+
removal than clinoptilolite for dairy and piggery wastewaters, and for
synthetic solutions containing high NH4+ concentrations (350-750 g
NH4-N m-3). At all equilibrium NH4+ concentrations tested
(0.2-300 g NH4-N m-3), NH4+ removal by both mordenite and
clinoptilolite was significantly (P < 0.0001) reduced by the presence
of competing sodium (Na+) cations in the synthetic solutions. The
maximum amounts of NH4+ removed by coarse and fine clinoptilolite
and coarse and fine mordenite, calculated by the Langmuir model, were 5.77 and
5.74, and 8.09 and 8.28 g NH4-N kg-1, respectively. In the slow
flow-through experiment (0.47 mm min-1), NH4+
breakthrough (>1.2 g NH4-N m-3) for both zeolite sources
(regardless of their particle sizes) did not occur even after receiving 40 bed
volumes (BV) of wastewaters containing 100 g NH4-N m-3. The
NH4+ removal at this breakthrough was approximately 99 g NH4-N
m-3 of wastewater throughput, which equates up to 5.8-6.5 g NH4-N
kg-1 zeolite. In contrast, at a faster loading flow rate (15.9 mm
min-1), the breakthrough was almost immediate (1 BV) for coarse
zeolites and after 22 BVs for fine zeolite. The NH4+ breakthrough
capacity for fine mordenite was 2.0-4.4 g NH4-N kg-1 zeolite. Fine
zeolites were more effective than coarse zeolites in removing wastewater
NH4+ (95% and 55% removal, respectively), even after receiving 64 BV
of wastewater.
Keywords zeolite; clinoptilolite; mordenite; ammonium
removal; wastewater; dairy effluent; piggery effluent; synthetic effluent;
agricultural wastewaters
New Zealand Journal of Agricultural Research, 1998, Vol. 41: 427-446
0028-8233/98/4103-0427 $7.00/0 (c) The Royal Society of New Zealand
1998
PDF file of entire paper: medium quality (1596K); (scanned from paper original: notes about this process)
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