Algal growth and nutrient uptake are not only affected by the
availability of nutrients, they also depend on complex interactions
among physical factors such as pH (Azov and Shelef,
1987), light intensity, temperature (Talbot and De la Nou¨ e,
1993), and biotic factors. The first biotic factor significantly
influencing algal growth is the initial density, it is expected that
the higher the algal density, the better the growth and the higher
the nutrient removal efficiency (Lau et al., 1995). However,
the high algal density would lead to self-shading, an accumulation
of autoinhibitors, and a reduction in photosynthetic efficiency