Filter Foam Sheet Experiments with Coagulated Particles
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
Experiments
A preliminary experiment was run to determine if better filtration performance could be achieved after dosing 5 NTU raw water with alum. A very high dose of alum was used, 25 mg/L, which is fairly unrealistic. To achieve this alum dose level, it would be necessary to install another alum doser prior to the filtration unit.
Experiment 1: 25 mg/L Alum Dose
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.
Experiment Set 2: Depth Filtration
The 5 NTU raw water turbidity level was acheived using the raw water turbidity process.