In order to obtain conditions that better resemble those of an AguaClara plant, an alum dosing system and a rapid mix tube were added to our experimental setup. Ideally, these slightly larger and "stickier" particles are more likely to be trapped in the foam resulting, in a lower effluent turbidity.
Figure 1: Experimental Setup with Alum Dose
Preliminary experiments were run to determine if better filtration performance could be achieved after dosing 5 NTU raw water with alum.
A series of experiments were run at a constant flow rate with a low, realistic alum dose of 1.5 mg/L in order to determine whether foam filtration acted as either a function of depth, or a function surface area.
The 5 NTU raw water turbidity level was achieved using the raw water turbidity process.