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On-Site Wastewater Treatment and Disposal Systems - Forced ...

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solution. It can be used to remove either ammonium or nitrate nitrogen<br />

from wastewaters. This process has been employed in full-scale water<br />

<strong>and</strong> wastewater treatment plants for several years (61)(67)(68), but<br />

there is no long-term experience with the process for nitrogen removal<br />

in onsite applications.<br />

Nitrogen removal by ion exchange has potential for onsite application,<br />

since it is very effective <strong>and</strong> is simple to operate. Unfortunately, per-<br />

iodic replacement of the exchange media is expensive <strong>and</strong> regeneration of<br />

the media onsite does not appear to be practical at this time. <strong>Site</strong><br />

conditions <strong>and</strong> climatological factors should not limit its application.<br />

a. Ammonia Removal<br />

Ammonia removal may be achieved by employing the naturally occurring ex-<br />

change media, clinoptilolite, which has a high affinity for the ammonium<br />

ion (61). Laboratory experience has shown that packed columns of cli-<br />

noptilolite resin (20 x 40 mesh) will effectively remove ammonium ion<br />

from septic tank effluent without serious clogging problems (2). Regen-<br />

eration with 5% NaCl was successful over numerous trials. BreaktQrough<br />

exchange capacity of this resin was found to be about 0.4 meq NH4 /gram<br />

in hard water at application rates of 10 bed volumes per hr. (This<br />

value will vary, increasing with decreased hardness.) Very large quan-<br />

tities of resin are required to treat household wastewaters (approxi-<br />

mately 10 lb per day). <strong>Treatment</strong> of segregated graywaters substantially<br />

lower in ammonium concentration decreases the amount of resin needed.<br />

This process employs a packed column or bed of the exchange resin fol-<br />

lowing a septic tank. The waste is pumped from a sump to the column in<br />

an upflow or downflow mode on a periodic basis. <strong>On</strong>ce the resin has been<br />

exhausted, it is removed <strong>and</strong> replaced by fresh material. Regeneration<br />

occurs offsite.<br />

Operation <strong>and</strong> maintenance of this process requires routine maintenance<br />

of the pump <strong>and</strong> occasional monitoring of ammonium levels from the pro-<br />

cess. Replacement of exhausted resin is dictated by wastewater charac-<br />

teristics <strong>and</strong> bed volume. There are insufficient data at this time to<br />

delineate labor, power, <strong>and</strong> resin requirements.<br />

b. Nitrate Removal<br />

Nitrate removal from water may be achieved by the use of strong <strong>and</strong> weak<br />

base ion exchange resins (68)(69). There are very little data available<br />

192

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