Methodology
64
 Number of aerators in a raceway pond (Na)
Aerators are used in raceway pond for several reasons such as:
mixing, temperature control, CO2 dispersion and maintainig
proper oxygen depletion that can harm the microalgae. Therefor
We propose the use of one aerator per pond (Na=1), with capacity
of En =35KW.
Note : After the secondary treatment, and in order to harvest the microalgae biomass, it is
necessary to stop the growth: by reducing exposure to light, by covering the raceway basins
partially or completely with opaque materials such as shade sails and wait 3 hours before
directing the treated water to the disinfection basin, to allow the microalgae to settle naturally
to the bottom of the raceway ponds, enabling sedimentation. The proposed harvesting technique
is manual harvesting, throught the use of nets to delicately collecte the top layer of microalgae
biomass.
6.5.2.1. 2.Sizing of raceway pond intended for microalgae cultivation
Sizing calculation of Raceway pond intended for microalgae cultivation are as follows:
 Calculating of raceway pond surface area (S)
We have : S = L×W
With :
S : Surface area of raceway pond (m
2 ).
L : length of raceway pond (m).( we assume that : L= 5 w = 5×26= 130m).
W : width of raceway pond (m).( we assume that : W=26 m).
 Calculation of the raceway pond volume(V)
Wa assume that : V= 10% VT
With :
V : Volume of raceway pond intended for microalgae cultivation (m
3 ).
VT: Total volume of raceway ponds intended for secondary treatment (m
3 ).
We assume that the depth of this raceway pond is equal to : 0,5m.