Which parasite is removed less effectively by primary sedimentation?

Primary sedimentation in wastewater treatment primarily focuses on the removal of solids through sedimentation. During this process, larger and heavier particles settle to the bottom, while lighter particles and pathogens may remain suspended in the liquid.

Entamoeba histolytica is a protozoan parasite that can exist in a cyst form, which is resistant to environmental conditions and may not settle out during the sedimentation process as effectively as larger organisms. This cyst form can remain suspended in the wastewater and may not be adequately removed by primary sedimentation alone.

In contrast, parasites like Ascaris and Taenia, which are larger helminths, tend to be more effectively removed during primary sedimentation due to their size and weight. Schistosoma, while also relatively small, has a different life cycle stage that may be more susceptible to removal through sedimentation processes.

Therefore, because of the characteristics of Entamoeba histolytica as a protozoan, it is less effectively removed during primary sedimentation compared to larger helminths.