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Abstract
The conventional water resources in Egypt are limited to mainly the Nile
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River and groundwater. Egypt is optimizing the use of freshwater and
exploring the use of new non-conventional sources of water, such as
agricultural drains. Bilbeas and El-Qalyoubia drains are two of the most
polluted water streams in Egypt. One of the proposed methods to enhance the
drain self-purification capacity is the use of submerged biofilter (SB).
Four streams pilot were installed at KP 35.0 of Bilbeas drain, and two streams
were installed at KP 12.0 of El-Qalyoubia drain. The experimental work was
divided into two stages. Stage ”1” was carried out in Bilbeas drain during the
period (December 2005- July 2006). It included four runs, each two runs
preceded by start up period. whereas stage ”2” was done during the period
(June 2007- July 2007), and included one run preceded by start up period.
At Bilbeas drain three of the streams were equipped with three different
types of media (pall rings, star shape and gravel) working as SBs while the
fourth remained without any media to provide a corresponding reference for
the natural purification. The three biofilters had the same total surface area of
media -for biofilm growth, the same width, and depth, but differed in length
in the flow direction. The four streams were operated at the same time under
the same flow rate.
Results of the hydraulic study showed that, Pall rings medium has the
highest hydraulic conductivity (Kc) value of about 5.55 m/s, compared to 2.40
and 1.51 m/s for Star shape medium and Gravel medium respectively.
Pall rings biofilter achieved the highest percentage of flow passing through
the clean media to the total applied flow rates (8.7 - 19.0%), followed by Star
shape biofilter (8.6 - 18.0%) of the total applied flow rates, and finally gravel
(2.6 - 5.1 %).
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