Plants employing trickling filters, activated sludge, and spray irrigation present a possible health hazard to their employees due to

The presence of trickling filters, activated sludge, and spray irrigation in wastewater treatment processes can create conditions where airborne microorganisms are prevalent. In these environments, employees are at risk of inhaling these microorganisms, which can include bacteria, viruses, and other pathogens associated with treated waste.

Understanding that wastewater contains a diverse array of microbes, the aerosolization of these pathogens during treatment processes increases the likelihood of respiratory exposure. Inhalation of airborne microorganisms poses a significant health hazard, particularly for workers who are in close proximity to treatment operations.

Therefore, the correct answer relates to the risk posed by inhaling airborne microorganisms, highlighting the importance of proper safety measures and personal protective equipment for employees working in these areas. This focus on airborne exposure underscores a critical aspect of occupational health in environmental sanitation.