Question

The use of which one of the following membranes can check bacterial growth problems during reverse osmosis since higher operating temperatures are possible with these membranes?

• A. Polyvinyl
• B. Non cellulose acetate
• C. Cellulose acetate
• D. Acetate oxide

Hint:

Dairy Membrane Materials:
Non-Cellulose Acetate (Polyamide Composite) = Operates at HIGH TEMP ($50-65^\circ\text{C}$), suppresses microbial growth.
Cellulose Acetate = Limited to $< 30^\circ\text{C}$, susceptible to bio-fouling and enzymatic hydrolysis.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Polymeric membrane materials in dairy reverse osmosis: synthetic thin-film composite non-cellulose acetate membranes (polyamide, polysulfone) withstand high operating temperatures ($50-65^\circ ext{C}$) and wide pH ranges (2--11), inhibiting microbial bio-fouling.
Key Formula or Approach:
\[ \text{Cellulose Acetate (CA): } T_{\max} \le 30 - 35^\circ\text{C (Prone to Bio-fouling)} \quad \longleftrightarrow \quad \mathbf{Non\text{-}CA \text{ (Polyamide/Polysulfone): }} T \approx 50 - 65^\circ\text{C (Sanitary Run)} \]

Step 2: Detailed Explanation:
In membrane technology and dairy reverse osmosis (RO) concentration:
1. Cellulose Acetate (CA) Membranes: Thermally and chemically labile; restricted to low operating temperatures ($< 30^\circ - 35^\circ ext{C}$) and narrow pH ($4 - 7.5$). Operating at ambient $25^\circ - 30^\circ ext{C}$ promotes severe bacterial growth, slime formation, and bio-fouling on membrane surfaces.
2. Non-Cellulose Acetate (Synthetic Thin-Film Composite Polyamide Polysulfone) Membranes (B): Feature exceptional thermal, chemical, and mechanical stability. They operate reliably at elevated temperatures ($50^\circ ext{ to } 65^\circ ext{C}$):
- High-temperature operation suppresses mesophilic bacterial proliferation, checking bio-fouling during continuous processing runs.
- Increases water flux by lowering milk fluid viscosity.

Step 3: Final Answer:
Hence, Non cellulose acetate membranes can check bacterial growth problems, corresponding to option (B).