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Following the flocculation, the stream enters a sedimentation tank, where the flocs begin to settle. This settling creates a "blanket" of flocs, which serves to trap more flocs and provide effective filtration as it grows. The floc blanket is an integral part of the AguaClara technology and enables the system to acheive much lower effluent turbidity.
Underdosing
An underdosed system occurs when the alum dosing is lower relative to the dosing conditions that are considered "ideal." In this situation, the flocs that are formed will be made up of a larger portion of suspended particles, which in our system are clay particles, and a smaller portion of the flocs will be composed of the alum. This results in a smaller floc and, consequently, a more dense floc blanket.
Overdosing
An overdosed system is accomplished by providing an alum dose that is at a higher concentration than what is considered to be the "ideal" dose. In this case, the flocs that are formed will have a higher alum-to-suspended-particle ratio. The flocs are therefore larger and more "fluffy" and the resulting floc blanket is less dense.