Role of membranes and activated carbon in the removal of endocrine disruptors and pharmaceuticals

Endocrine disrupting chemicals and pharmaceuticals represent two classes of emerging contaminants that are ubiquitously present in municipal wastewater effluents. Some of these contaminants have been shown to impact aquatic organisms at trace concentrations (i.e., ng/L). Moreover, the public has expressed human health concerns regarding the presence of emerging contaminants in water reuse projects. The primary objective of this investigation was to determine the efficacy of various membranes and activated carbons for the removal of endocrine disruptors, pharmaceuticals, and personal care products. A suite of structurally diverse target compounds was selected for evaluation based largely upon occurrence and molecular structure. Several membrane types and applications were evaluated at pilot- and/or full-scale, including: microfiltration, ultrafiltration, nanofiltration, reverse osmosis, electrodialysis reversal, membrane bioreactors, and combinations of membranes in series. Granular activated carbon was evaluated at bench-scale using rapid small scale column tests and at two full-scale utilities. Microfiltration and ultrafiltration were found to reject very few target compounds; however, some loss of steroidal type compounds was observed. Nanofiltration and reverse osmosis were capable of significant rejection of nearly all target compounds, though compounds were detectable at trace levels in permeates. Granular activated carbon was highly effective at removing all target chemicals. However, break-through curves clearly demonstrated that compounds with greater hydrophilicity breach activated carbon faster than hydrophobic compounds. In full-scale applications, the impact of regeneration was observed as activated carbon filters that received regular regeneration had minimal breakthrough of organic contaminants, while non-regenerated filters displayed no removal of target compounds. Findings confirm that membrane and carbon processes are capable of greatly reducing the concentrations of emerging contaminants; however, several compounds are detectable in membrane permeate and carbon effluent.