Animal sources of pathogenic microorganisms include waste from slaughtering house and meat processing facilities, runoff from pasture land and feedlots, and rats or other animals that frequent sewers. Pathogenic microorganisms are only a small percent of the total microorganisms entering a wastewater treatment facility but can cause serious illness among workers that can be spread to friends and family. Each type of microorganism has its own survival requirements, but in general most of the significant pathogenic microorganisms survive longer at lower temperatures, in cleaner water and at near normal pH. Parasites are generally more resistant than other types of microorganisms to wastewater and sludge treatment processes. At wastewater treatment facilities, these microorganisms are found not only in the wastewater but throughout the working environment. High numbers are found in poorly ventilated enclosed area where the wastewater is agitated or sprayed, and near sludge processing areas.
Airborne microorganisms are in the highest concentration near aeration tanks.
However, studies indicate that the highest levels of fungi, such as Aspergillus, are found in sludge processing areas, especially sludge composting areas. Bacterial Hazards Salmonella. Symptoms include headache, diarrhea, and abdominal cramps. Fever, nausea, and vomiting may also frequently occur. Symptoms usually develop in 12 to 36 hours but can occur from 6 to 72 hours after infection.