Purification of Phenolic-Laden Wastewater from the Pulp and Paper Industry by Using Colloid-Enhanced Ultrafiltration

The removal of three phenolic pollutants with variable degrees of chlorination from water was investigated: 2-monochlorophenol (MCP), 2,4-dichlorophenol (DCP), and 2,4,6-trichlorophenol (TCP). These compounds are often found in pulp and paper mill wastewater effluent. Colloid-enhanced ultrafiltration (CEUF) techniques were investigated for wastewater purification. Pollutants can associate with colloids: surfactant micelles or surfactant–polymer complexes solubilize nonionic compounds. In this application of CEUF, the micelles or surfactant–polymer complexes are ultrafiltered from solution with solubilized chlorinated phenol pollutant. An advantage of surfactant–polymer complexes, compared to only surfactants, is reduction of surfactant monomer (unaggregated surfactant) concentration. These surfactant monomers can pass through the ultrafiltration membrane, reducing the purity of the product water. Excellent solute rejections are observed for both micelles and surfactant–polymer complexes, generally exceeding 90% for DCP and TCP, even exceeding 99% in some cases. The ratio of the solubilization constant in micelles to that in surfactant–polymer complexes varied from approximately 1 to 5. In micelles, rejection increases in the order MCP