What distinguishes direct filtration from indirect filtration?

Direct filtration is characterized by the absence of a sedimentation step in the treatment process. This means that the water is treated by passing it directly through filters without first allowing solids to settle out in a sedimentation basin. This method is typically employed when the source water is relatively clean, as it allows for a more straightforward and efficient treatment process.

In contrast, indirect filtration involves a sedimentation process, where heavier solids settle out before the water is filtered. This additional step can help in reducing the load on the filters, but it also adds complexity, time, and space requirements to the treatment process.

The requirement for direct filtration is particularly crucial in systems handling water with low turbidity, as the absence of sedimentation can lead to quicker processing and potentially lower operational costs. This distinguishes it from indirect filtration, where the sedimentation phase serves to improve overall water quality before filtration.