An assessment of the cleaning solutions' purification by membrane filtration

摘要

The results of the purification of contaminated cleaning solutions (a single-phase detergent) emanating from a diary industry were reported. Flat-sheet ultrafiltration (UF) and nanofiltra-tion (NF) membranes that differed in their molecular weight cut-offs were evaluated for their potential use in the recovery of cleaning solutions. The experiments were performed in a stirred cell operating in a dead-end filtration mode. The membranes were tested under different transmembrane pressures (0.5-4bar), mainly for the purpose of: (ⅰ) a long-term evaluation of membrane hydraulic performance, (ⅱ) an assessment of fouling tendency, (ⅲ) an evaluation of the quality of the recovered solution in comparison with the fresh detergent, and (ⅳ) an assessment of the chemical stability of a polymer material. Studies have demonstrated the usefulness of membrane filtration using polymeric membranes for the recovery of a single-phase detergent for the purpose of its reuse in cleaning systems. The recovered detergent maintained its basic cleaning properties, i.e. high pH, high concentration of NaOH and low value of surface tension. Moreover, the NF membranes and the tight UF membranes showed a high separation of specific milk components and organic matter expressed as TOC and COD.