Removing pathogens is the most critical part of wastewater treatment. Pathogens are organisms that cause disease; they include viruses, protozoa and bacteria. Examples in wastewater include salmonella, Vibrio cholera, Entamoeba histolytica, and cryptosporidium, although almost all disease organisms could be present in wastewater.Viruses are organisms too small to be seen by light microscopy. They are an obligate parasite, dependent on a host cell for its metabolic and reproductive needs. Pathogens may be found in wastewater generated anywhere in the house. Any human contact with water results in the potential to add pathogens to the environment. Because of their role in
