The management, separation, and recovery of particulate matter from treatment processes can take a number of forms. In high-value systems where particulate matter is re-used and fluid volumes are relatively small the flow is often centrifuged. In systems where fluid volumes are large, then gravitational separation can be used to provide a cost effective solution. This is normally achieved in settlement ponds where flow speeds are reduced and suspended materials are allowed to settle out.
Settlement ponds must periodically be drained, and the resulting consolidated material (often toxic and requiring special disposal treatment) is removed mechanically. In flood management systems these types of ponds are increasingly taking the form of managed wetlands.
Effective settlement in ponds can require the use of baffles to distribute flow to make best use of the available volume. If the surface is open to the environment, then the influence of high winds must be considered in the design of the pond as high surface stresses can re-entrain settled sediments and limit the efficiency of the gravitational separation.
CFD Solutions Ltd uses CFD to improve the design of settlement ponds and other systems designed for low and high volume solids separation.