This monograph delineates the retention mechanisms of emerging trace organic contaminants by several nanofiltration (NF) and reverse osmosis membranes. Retention of neutral trace organics by a tight NF or RO membrane is dominated by steric (size) exclusion, whereas both electrostatic repulsion and steric exclusion govern the retention of negatively charged trace organics by a loose NF membrane. Speciation of trace organics may lead to a dramatic change in retention as a function of pH, with much greater retention observed for ionized, negatively charged trace organics. Retention of the...