Which of the following accurately describes membranes in water treatment?

Membranes in water treatment play a crucial role in the separation process, which is based on physical and chemical properties. This involves a physical barrier that allows for the selective passage of water while rejecting contaminants, such as suspended solids, bacteria, viruses, and dissolved salts, depending on the type of membrane and its pore size. This separation process is fundamental to various membrane technologies, including microfiltration, ultrafiltration, nanofiltration, and reverse osmosis, each with specific capabilities for treating water.

The application of membranes specifically capitalizes on the differences in size, charge, and chemical composition of particles compared to water molecules, effectively purifying the water. This method is key in producing safe drinking water and treating wastewater while minimizing the introduction of chemicals that could alter the water's composition in other treatment methods.

In contrast, the other choices pertain to functions that membranes do not provide. For instance, membranes do not engage in chemical disinfection themselves; rather, they physically separate pathogens from water. They also do not add minerals or control pH levels; in fact, some processes with membranes, such as reverse osmosis, can remove essential minerals from water, which is why remineralization steps are often introduced in water treatment systems. Thus,