What is the range of virus removal achieved by primary sedimentation?

Primary sedimentation typically involves the physical separation of solids from wastewater through gravity settling. During this process, larger particles and some microorganisms, including viruses, can be removed from the wastewater.

The range of virus removal that results from primary sedimentation is significantly influenced by several factors, including the characteristics of the wastewater, the size and type of viruses present, and the specific design and operational conditions of the sedimentation tank. Studies indicate that primary sedimentation can achieve an approximate virus removal efficiency within the range of 0-30%. This means that while some viruses can be removed, the efficiency is relatively low in comparison to other treatment processes that follow sedimentation.

This level of removal can be attributed to the fact that many viruses are much smaller than the particles that settle out during sedimentation. Consequently, while primary sedimentation does provide some degree of virus removal, it is often not sufficient to significantly reduce viral loads without subsequent treatment processes, such as secondary or tertiary treatment.