Reactive dyes rejection and textile effluent treatment study using ultrafiltration and nanofiltration processes

Ultrafiltration and nanofiltration processes were used to treat synthetic reactive dyes aqueous solutions and a raw textile effluent supplied from rinsing baths of Spanish textile industry. The influence of the reactive dyes molecular weights and the effect of the used membranes types and cut-offs were investigated with regard to the permeate flux at different transmembrane pressures (2–7 bar for UF and 4–15 bar for NF). The extent of colour retention, COD and conductivity was determined in order to monitor the membrane's separation efficiencies aiming at waste water treatment, water reuse and chemical usage minimisation. High COD retentions (80–100%) were achieved using UF and NF processes. Good conductivity rates (80%) and high COD and colour retention rates (> 90%) were obtained for both NF 200 and NF 270 membranes for all studied dyes solutions. An improvement of the rinsing wastewater quality was obtained using UF and NF processes.

► Synthetic dye solutions and raw textile effluent were treated by UF and NF membranes.
► We study the effect of MW of dyes and the type of membranes versus the permeate flux.
► High COD retentions were achieved using UF and NF processes.
► An improvement of the wastewater quality was obtained using UF and NF processes.