Which of the following processes involves the use of pressure differences for filtration?

Membrane filtration is a process that utilizes pressure differences to separate contaminants from water. In this process, water is pushed through a semi-permeable membrane, which acts as a barrier to particles, pathogens, and other dissolved substances based on size and charge. The pressure applied creates a driving force that enhances the flow of water through the membrane while retaining the contaminants on one side. This method is effective in removing a wide range of particles, including bacteria and viruses, making it a crucial technology in water treatment processes.

Other processes such as coagulation, sedimentation, and biological treatment do not primarily rely on pressure differences for filtration. Coagulation involves adding chemicals to aggregate particles into larger flocs, which then can be removed by sedimentation. Sedimentation allows particles to settle under gravity, and biological treatment relies on microorganisms to break down organic matter, neither of which employs pressure-driven filtration as the core mechanism.