National League for Nursing (NLN PAX) Practice Exam

Which of the following processes is used to free contaminated water of bacteria?

1. Passing it through charcoal

2. Boiling it for several minutes

3. Filtering it through sand

4. Adding chlorine tablets

The correct answer is: Passing it through charcoal

The process of passing contaminated water through charcoal effectively removes bacteria due to the adsorption properties of activated charcoal. Activated charcoal has a large surface area and numerous micro-pores that allow it to trap and hold contaminants, including bacteria, as water passes through. This purification method is particularly useful in applications where chemical disinfection is not viable or desired. While boiling, filtering through sand, and adding chlorine are all methods that can aid in purifying water, they function in different ways. Boiling is a physical process that kills bacteria through high temperatures, filtering removes larger particles and some microbes depending on the filter media, and chlorine is a chemical disinfection method that can kill bacteria and viruses. However, the specificity of charcoal to adsorb a wide range of contaminants makes it a unique choice for effectively reducing bacterial presence in water.