What is the term for raw water that has undergone pretreatment before entering membrane arrays?

• A. Feedwater
• B. Permeate
• C. Effluent
• D. Influent

Answer: (A)

The term for raw water that has undergone pretreatment before entering membrane arrays is "feedwater." Feedwater refers specifically to the water that is prepared and conditioned to remove contaminants and prepare it for further processing, such as filtration or membrane treatment. This pretreatment is crucial, as it helps in enhancing the efficiency and longevity of the membrane systems by reducing fouling and scaling.

Permeate refers to the treated water that passes through the membrane, while effluent typically refers to the treated water that is discharged from a treatment system. Influent, on the other hand, describes the incoming water entering a treatment facility before any processing or pretreatment occurs. Understanding these distinctions highlights the role of feedwater as a critical step in the water treatment process, especially in systems utilizing membrane technology.