A very interesting paper on use of algae to treat wastewater.
Slide No. 2 and 3 give the total power consumption by Wastewater treatment plants.
The investment required for new plants is estimated at US $ 20 Billion in the next 10 years. (Slide 4).
Slide 8 clearly states 'ENERGY SAVINGS REQUIRED' - this is exactly the problem that Nualgi addresses - reduction in capital cost, reduction in power consumption and even generation of income from wastewater - either food in form of fish or biodiesel.