Polyacrylamide is a versatile water-soluble polymer that finds widespread applications in various industrial and environmental processes. It works primarily due to its high molecular weight and functional groups, specifically in terms of its ability to flocculate, or coagulate, particles and enhance solid-liquid separation. 

When polyacrylamide is added to a solution or suspension, it interacts with the particles or colloids present. Anionic polyacrylamide, in particular, carries negatively charged functional groups along its polymer chain. These groups can attract and bind to positively charged ions, such as metal salts, or positively charged particles suspended in the medium.

In water treatment processes, polyacrylamide is often used to aid in clarification, dewatering, and sludge thickening. As it is added to a water or wastewater sample, the anionic polyacrylamide molecules adsorb onto the suspended particles, forming larger agglomerates or flocs. This process is known as flocculation.

The formation of flocs helps in several ways. First, it brings together smaller particles to form larger, more settleable aggregates. Second, it increases the size and weight of the particles, facilitating their settling or separation from the liquid phase. Finally, the flocs formed by polyacrylamide can help trap fine particles, colloids, and even dissolved substances, improving the overall water quality.

In addition to flocculation, polyacrylamide can also act as a viscosity modifier, meaning it can increase or decrease the viscosity of a liquid. This property is useful in various industrial processes, such as drilling fluids, enhanced oil recovery, and papermaking.

Overall, polyacrylamide's ability to flocculate and modify the viscosity of solutions makes it a valuable tool in a wide range of applications, including water treatment, mining, petroleum, agriculture, and many more. Its versatility stems from its tunable properties, allowing it to be customized based on specific process requirements and desired results.