Micellar-enhanced ultrafiltration of dairy wastewater with anionic and nonionic surfactants

Abstract

In this study, the potential of MEUF process has been analyzed to treat a real dairy wastewater. For this purpose, linear alkylbenzene sulfonate (LAS) and Triton X-100 (TX-100) have been used as anionic and nonionic surfactants, respectively. The ranges of 2–3.5 bars and 0–4 mM are selected for transmembrane pressure (TMP) and surfactants concentration, respectively, to investigate their effects on the permeate flux as a function of operating time. Moreover, it is revealed experimentally that rejection of pollution indices including chemical oxygen demand (COD) and total dissolved solid (TDS) is affected by TMP and feed surfactant concentration, while turbidity is remained relatively unchanged. According to the experimental results analysis, the increase of feed surfactant concentration has negative and positive effects on the permeate flux and rejection efficiency, respectively. TMP enhancement also leads to the higher flux values but it does not necessarily improve the rejection. Furthermore, the effectiveness of anionic surfactant in pollution indices elimination is more than the nonionic one. In the treatment combination assessed for the factors, the best rejection values of COD, TDS, and turbidity using LAS surfactant with polyacrylonitrile (PAN-350) 20-kDa poly(ethylene glycol) membrane are almost 93, 52, and 99.9%, respectively.

Keywords:

• MEUF
• Surfactant
• Dairy wastewater
• Permeate flux
• Rejection

Acknowledgments

The author wishes to thank Mr A.S. Asgari, M. Khandan, M.R. Skandari, and Mrs S. Sharifi for their kind helps.