What happens to the contaminants and some water in the RO process?

In the reverse osmosis (RO) process, contaminants and some portion of the water are effectively separated out from the purified water. The function of the RO membrane is to allow clean water to pass through while filtering out impurities and contaminants such as salts, bacteria, and larger particulates.

During this process, the contaminants that are filtered out, along with a certain percentage of water that does not pass through the membrane, are sent to the drain or back to the feed side. This is a critical aspect of the RO system, as it ensures that impurities are removed and do not remain in the purified water, which would compromise water quality for hemodialysis or other applications. The water that is sent to the drain contains these contaminants, preventing them from affecting the efficacy of the system and ensuring that the output water meets safety and quality standards.

In contrast, the other options suggest methods of handling the contaminants or water that are not typical in a standard RO process. Reusing filtrate, evaporating contaminants, or storing them for later use do not align with the operational principles of an RO system and do not contribute to maintaining the water quality necessary for hemodialysis.