What is a major concern regarding the presence of oil and grease in wastewater?

The presence of oil and grease in wastewater is a significant concern primarily because it may cause explosions and line blockages. When oil and grease enter sewer systems, they tend to float on the surface of water, accumulating and hardening over time. This accumulation can lead to substantial blockages in pipes, which may disrupt the flow of wastewater.

Moreover, in certain situations, when oil and grease are subjected to temperature changes, they can ignite, posing a serious explosion risk in confined spaces like sewers. This safety hazard further emphasizes the importance of managing oil and grease in wastewater effectively to prevent both operational and safety incidents.

Other choices provided present misconceptions about the effects of oil and grease. For example, while it may seem that oil and grease could potentially enhance some water treatment processes or improve nutrient balance, in reality, they usually hinder effective treatment and create challenges that impact overall wastewater management. Additionally, while corrosion could be a concern in some contexts, it is not as direct or immediate a risk as blockages and explosion potential. Understanding these risks helps in developing procedures for monitoring and controlling oil and grease levels in wastewater management systems.