What type of pollutants can cause obstruction in flow systems?

Solid or viscous pollutants are the primary types of pollutants that can cause obstruction in flow systems. This is due to their physical properties; solid pollutants can accumulate and physically block pathways, drains, and conduits, leading to reduced flow or complete blockage. Viscous pollutants, which have a higher resistance to flow, can also hinder the normal movements of fluids through pipes or channels, contributing to pressure build-up and operational difficulties in wastewater treatment facilities and natural waterways.

While gaseous and liquid pollutants can have significant environmental impacts, they typically do not cause physical obstructions. Gaseous pollutants tend to disperse into the atmosphere and generally do not block flow systems. Liquid pollutants, although they can contaminate water bodies, do not tend to obstruct flow in the same way that solids do. Particulate matter may affect systems indirectly by settling out and potentially causing some obstruction, but it is the solid and viscous materials that are primarily responsible for direct blockages.