Biodiesel wastewater treatment using nanofiltration membranes

Abstract

Water reclamation and reuse are economically and environmentally important issues for industries. Costly and ineffective treatments such as coagulation, flocculation, and/or biological treatment are the most widely used technologies for these processes. The aim of this paper is to study membrane separation to treat biodiesel wastewater as an alternative. To achieve this goal, two commercial nanofiltration membranes were used to treat medium-high strength wastewater. An Inopor Nano tubular ceramic membrane was used in a cross-flow module and a NF99HF Alfa Laval polymeric flat sheet membrane was used in a dead-end filtration cell. Wastewaters were prepared and treated with these membranes achieving maximum fluxes of permeate of 53.1 L h-1 m-2 for the ceramic membrane and 12.2 L h-1 m-2 for the polymeric membrane at 20 bar and 30 °C. The results shows a chemical oxygen demand retention between 80–85 % were obtained for both membranes, while the retention of ionic species due to changes in electrical conductivity was 76–89 %. Transmembrane pressure, organic load, hydraulic permeability, cross-flow velocity, wastewater characterization and fouling resistance-in-series analysis were also made and analyzed in detail in order to explore the actual use of nanofiltration.