may be a result of a lower concentration of Total Nitrogen within

the whole system.    As the lab analyses become available for the

mid-winter period we will see if the lower temperature is indeed

limiting the nitrification and denitrification processes.

4.2 Site 2

     At Site 2, the recirculating sand filter was installed in

August of 1992 and the pump was started in early November. As can

be seen in Figure 4.5, the nitrate levels in the pump chamber of

the recirculating sand filter began to rise appreciably within a

couple of weeks.    This coupled with a corresponding decrease in

ammonia levels again indicates that the nitrifying bacteria had

become adequately established to nitrify the ammonia-N to nitrate-

N.

      We feel that the nitrate levels rose faster in this system

 than the other system because although the pump in the sand filter

 was not started until early November, effluent from the septic tank

 was being applied to the top of the sand filter since the system

 was first installed. This would allow the nitrifying bacteria to

 have become somewhat established within the sand filter before the

 pump within the sand filter was originally started.

      By comparison, no effluent was applied to the top of the sand

 filter at Site 1 until early October when the pump within the sand
 filter was originally started.     This meant that the nitrifying
 bacteria had no chance at becoming established in the sand filter

 until the pump began pumping effluent to the top of the sand

 filter.


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