Nanofiltration of ammoniacal wastewaters containing phenols and cyanide ions is investigated in order to obtain concentrate streams enriched in ammonium and phenol and permeate streams enriched in cyanide ions. This is achieved through the variation of the feed pH, when nanofiltration is run in concentration mode. The concentrate streams are further fractionated by steam stripping. The nanofiltration/steam, stripping integrated process allows the confinement of ammonium, phenol and cyanides into three separate streams that can be further subjected to specific treatments. The nanofiltration experiments were carried out with model solutions and with coke plant ammoniacal wastewaters in a DSS plate-and-frame Lab-Unit M20, equipped with HR-98-PP membranes. The wastewaters concentration till recovery rates of 53% yields a pH variation ranging from 9.4 to 8.8. The decrease to a pH of 9.0 is associated with the preferential permeation of the cyanide ions. Further pH decrease favors the displacement of feed solute equilibria towards positively charged and neutral species and due to electroneutrality requirements the cyanide can no longer permeate through the membrane. The pH of 9.0 is obtained for a recovery rate of 40%, where the cyanide enrichment in the permeates is maximal. Based on the solution-diffusion model a B parameter is estimated as being equal to 7.77 x 10(-7) (ammonium) and 6.03 x 10(-8) m/s (phenol). For the cyanide ions its value varies with the feed composition. (C) 2004 Elsevier B.V. All rights reserved.