CWEA Advanced Water Treatment Practice Test

Ultraviolet (UV) disinfection is highly dependent on the clarity of the water being treated. In water containing high levels of suspended solids, the effectiveness of UV treatment can be significantly impaired. This is primarily because suspended particles can absorb or scatter UV light, which hinders the light’s ability to penetrate the water and effectively inactivate pathogens.

When these suspended solids are present, they can indeed form deposits on the UV lamps, leading to reduced intensity of the UV light reaching the water. If the lamps are covered with deposits, less UV light can effectively disinfect the water, thereby compromising the treatment process. The significant reduction in disinfection capability due to the presence of these solids underscores the importance of maintaining clean water conditions for effective UV treatment.

In contrast, while filtering out solids before UV treatment can enhance the disinfection process, it does not eliminate the challenges posed by high concentrations of suspended solids. The other options do not accurately address the relationship between UV effectiveness and water quality in terms of suspended solids.