Methodology
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 Calculation of the total mass of microalgae in raceway pond (Xa)
We have : Xa in raceway ponds intented to the secondary treatment is equal to 6777
Kg, therefor we assume that Xa in the cultivation raceway pond is equal to : 7000kg.
 Calculation of the concentration of microalgae in the raceway pond
We have :
[Xa]=
𝑋 𝑎
𝑉
 Number of aerators in a raceway pond (Na)
We assume the need of two aerators (Na=2) in the raceway pond intended for
microalgae cultivation, with capacity of : En =44KW.
The raceway ponds calculation results are mentioned in the tables 21(Chapter 3).
6.5.3. Tertiary treatment (disinfection)
Tertiary treatment is any chemical, physical or biological treatment that supplements primary
and secondary treatment in order to eliminate pathogens, bacteria and viruses.
According to the wastewater treatment plants in Algeria, sodium hypochlorite (bleach) is the
most widely used disinfectant at this stage of treatment, due to its availability on the market and
its low cost. For the Taoura WWTP, I propose disinfection with sodium hypochlorite.
In order to improve water contact with the disinfectant solution, a number of baffles will be
built inside the basin to increase water flow. Therefore, i propose 3 baffles, each 5m long and
2m wide.
 Chlorine injection dose (Dcl)
The chlorine dose required under normal conditions for treated effluent is
5 to 10 mg/l for a contact time of 30 minutes.
A dose of Dcl=10 mg/l for a contact time of tc=30 min is assumed.
 Daily chlorine dose (Dj)
The chlorine dose for disinfection is determined by the following function:
Dj = Qaver.d×Dcl
With:
Dj : chlorine dose for disinfection (Kg/d).