Which of the following is an example of a non-chemical feedwater treatment method?

The correct answer is ultrafiltration. This method is considered a non-chemical treatment since it primarily relies on physical processes to remove contaminants and particulates from water without the addition of chemical agents. Ultrafiltration utilizes a semi-permeable membrane that allows water and certain small dissolved substances to pass through while rejecting larger molecules, bacteria, and suspended solids. This technology is effective for purifying water and reducing turbidity, making it an essential part of feedwater treatment in various applications.

In contrast, the other options listed involve chemical processes or adjustments. Chemical dosing entails adding substances to water to achieve desired chemical characteristics or to remove impurities. Filtration, while it may seem physical, typically refers to conventional processes that may involve chemical aids. pH adjustment specifically involves adding chemicals to alter the acidity or alkalinity of water, ensuring that it falls within acceptable parameters for industrial use. Thus, ultrafiltration stands out as a purely physical method in the context of feedwater treatment.