The Egyptian Int. J. of Eng. Sci. And Technology,
Vol.12, No. 1 (Jan. 2009)
EIJEST
INCREASE OF SELF-PURIFICATION EFFICIENCY OF WATER
STREAMS USING ROTATING BIOLOGICAL CONTACTORS (RBC)
Diaa S. El Monayerie*, Nabil N. Atta*, Amro. A. El Baz* and Sami A. I. Dif**(1)
* Environmental Engineering Department,
Faculty of Engineering, Zagazig University, Egypt
** National Authority for Potable Water and Sanitary Drainage
ABSTRACT
Self-purification of water streams has an important role in enhancing drain water quality. This study proposes
external intervention to enhance the self-purification process. Two concrete channels were constructed on the
berm of a polluted stream to investigate the effect of using rotating biological contactor (RBC) discs on the
self purification efficiency of the stream. This RBC freely rotates under the effect of hydraulic discharge of
water in the two channels. Changing flow rates, spacing between stages of RBC and the number of stages
along the channels were considered to study their effect on the removal efficiency of chemical oxygen
demand (COD), dissolved oxygen and ammonia. Experimental results indicated that, under various flow rates
(20, 25, 30, 35 and 40 l/s) the highest percentage of COD was removed at a discharge value of 30 l/s. The
removal efficiency of COD using this flow ranged from (39.5 – 44.35%) compared to (6.3 – 16.5) in the
reference channel, with an enhancement ratio of about, 626 – 268%. Moreover the dissolved oxygen level
(DO) increased from 2.1 to 3.5 mg/l compared to 2.1 mg/l in the reference channel with an enhancement ratio
of about 167% and Ammonia concentration decreased from12.5 – 13.7 mg/l to 10.35 – 9.46 mg/l, compared
to relatively constant for the reference channel.
KEY WORDS: Aeration, Ammonia, Biofilm, COD removal, Dissolved Oxygen, Drain's water,
Organic Mater, Rotating Biological Contactors (RBC), Self-Purification.