Treatment of spent emulsion from a cable factory by an integrated UF/NF membrane system

The potential of using the integrated membrane system based on ultrafiltration (UF) and nanofiltration (NF) in purification of effluents from a cable factory was investigated. The UF experiments were performed using tubular membranes taking into consideration the composition of the treated effluents. The UF process was carried out within the range of parameters recommended for oil emulsion. The application of UF membranes with MWCO of 100 kDa results in the complete rejection of suspended solids and the retention of oil and lubricants at a level of 99%. The UF membranes employed exhibit a 96% passage of copper ions, which is the major component of spent emulsion. The average permeate flux during the UF pretreatment of wastewater produce during copper wire drawing amounts 45 l/m2h for the transmembrane pressure of 2 bar. The resulting UF permeate was further purified by NF to achieve the retention of remaining pollutants (oil and lubricants) and to reduce the content of copper ions. As a result of the NF process, the content of organic compounds in the permeate determined as TOC was below 1 mg/dm3, and the rejection of copper ions obtained with the AFC30 membrane was at a level of 92%. The quality of permeate obtained by the application of an UF/NF integrated membrane system allows the direct reuse of treated water for fresh emulsion top up.

The application of UF membranes made from PAN, PVC and PVDF with MWCO in the range of 50–100 kDa results in the complete reduction of suspended solids and the rejection of oil and lubricant at a level of 99%. The UF membranes demonstrate good flux stability during the pretreatment of spent copper wire drawing emulsion. These membranes allow production of the permeate with the SDI index recommended for spiral-wound modules. An outstanding advantage of the proposed combination of the membrane processes is the complete rejection of suspended solids, oil and lubricants. As a result of the NF process, the content of organic compounds in the permeate determined as TOC was below 1 mg/dm3, and the rejection of copper ions obtained with AFC30 membrane was at a level of 92%. Purification of the UF permeate in the NF process resulted in treated water which can be directly reused for fresh emulsion top up.