Micellar enhanced ultrafiltration in the treatment of dye wastewater: Fundamentals, state-of-the-art and future perspectives

Abstract

The rapid development of dye using industries (textile, paper, plastic, leather, printing, cosmetic, food and pharmaceuticals etc.), poor effluent management and disposal techniques have led to excess amounts of wastewater polluted with toxic dyes and heavy metal ions. The discharge of large volumes of toxic wastewater into the environment, particularly from small scale industries, causes extensive damage to natural ecosystems and human health. Therefore, the removal of these hazardous pollutants from effluents is of interest prior to release into natural water bodies. Micellar enhanced ultrafiltration (MEUF) shows a great potential as an effective, environmentally-friendly and sustainable operation in treatment of dye wastewater, particularly for diluted stream, for water reclamation and resource recovery. MEUF has been successfully investigated for removal organic dyes and heavy metal ions from aqueous solution, in single or binary system. In this review, we aim to provide an overview of the recent development, state-of-the-art and future perspectives of MEUF for treatment of dye wastewater. This article critically reviews the performance and capability of MEUF process in the treatment of dye wastewater with the consideration of the basic principles, transport modelling, membrane fouling, technical viability, and parameters affecting micellization, optimization of feed, process throughput and removal efficiency. The effects of type of surfactants, membranes, initial feed concentrations, operating conditions etc. on the process performance are reviewed. This review presents the evidence of simultaneous removal of co-existing pollutants (dyes and heavy metal ions) in dye wastewater using MEUF and also explores the feasibility and efficiency of biosurfactant instead of chemical surfactant. Besides, several ways to improve process efficiency are discussed along with the technical challenges and future opportunities for treating dye wastewater. Long-term performance of the MEUF system, membrane fouling, transport modelling, cost analysis and application on real wastewater should be paid more attention in the future studies.