Enzymatic cleaning restores the performance of biofouled membranes at mild conditions
Nicholas Popolizio, Xingpeng Zhang & Jeffrey Melzer
Semiconductor manufacturers require the highest water quality for their process. Multiple purification steps are required to achieve this level of ultrapure water, and those usually include multiple reverse osmosis (RO) membrane stages. To ensure reliability of both flow capacity and quality, membrane fouling from both inorganic and organic contaminants must be ensured using online chemical treatments as well as offline cleaning strategies. Biological fouling of membrane is an issue many ultrapure water treatment systems struggle with. Efficient cleaning of biofouled RO membranes is traditionally conducted using aggressive chemicals such as biocides, strong alkaline and oxidizing cleaners, that can damage the membrane. Another cleaning approach, less common but less damaging, involves the use of enzymes. Enzymes can be powerful targeted catalysts designed to break down organic macromolecules into smaller ones during normal clean-in-place (CIP) operations. Optimized enzymes formulations can provide many benefits such as reduced operational cost from longer run length in between CIPs, lower chemical consumption, extended membrane life and mitigated environmental impact from spent cleaning chemicals discharge. Optimized enzymes formulations provide many benefits such as reduced operational cost from longer runlength in between CIPs, lower chemical consumption, extended membrane life and mitigated environmental impact from spent cleaning chemicals discharge. This paper reviews the mechanisms of RO membrane biofouling, an overview of the traditional and novel membrane biofouling control (including and cleaning strategies and a comparison of the performance and benefits of both approaches through the presentation of a field application of enzymatic membrane cleaners in a semiconductor manufacturing effluent treatment facility.