Membrane technology for the recovery of contaminated single-phase acidic detergents

• A variety of operating conditions on UF and NF modules’ performance was evaluated.
• Purified acidic single-phase detergent maintained its cleaning properties.
• Operating conditions affect the quality of recovered detergent.
• Lactose rejection was higher on ceramic UF modules than on polymeric UF ones.

Pressure-driven membrane processes were investigated for the recovery of contaminated cleaning solutions (an acidic single-phase detergent). The experiments were performed in a semi-pilot membrane installation in cross-flow regime with the use of UF and NF differing in their configuration, MWCO and membrane material. The performance of the modules was characterised in terms of their retention characteristics, hydraulic efficiency and tendency to fouling. The influence of long-term filtration time and process conditions (transmembrane pressure, cross-flow velocity and temperature) on these parameters was evaluated. The results revealed that the recovery of spent acidic single-phase detergent is possible with the use of membrane processes. The permeates maintained their basic cleaning properties. The retention of protein from spent detergent amounted to 98.4–100%; however, the separation effectiveness of lactose was more varied (49.5–99.1%) and depended to a greater extent on MWCO and module material.