Photocatalytic and membrane processes are strong candidates for improving conventional water treatment processes. These advanced treatment methods are capable of removing many pollutant chemicals as well as pathogenic microorganisms. The objective of this work was to study the performance of small scale UV/TiO2 photocatalytic pilot plant process in treating secondary and tertiary treated effluent from a wastewater treatment plant in Bahrain. The performance was evaluated in terms of the efficiency of removing a chlorine resistant parasite, namely, Strongyloides Stercolaris, in addition to reducing the chemical oxygen demand (COD). The effect of pH and exposure time were considered. The performance of the UV/TiO2 was compared with small pilot scale ultrafiltration (UF) and reverse osmosis (RO) membrane processes. Treatment of the samples with each of the UV/TiO2, UF and RO processes resulted in a complete removal of the S. stercolaris parasites. Moreover, the chemical oxygen demand was reduced by about 50, 64 and 86% with each of UV/TiO2, UF and RO. The specific power consumption of the UV/TiO2 process was estimated to be about 4.0 kWh/m(3) for each of UV/TiO2 and sea water RO (SWRO)and 1.0 kWh/m(3) and 0.9 kWh/m(3) for each of brakish water RO (BWRO) and cross flow UF, respectively. The UV/TiO2 process produces no waste stream, whereas the RO and UF processes generate waste streams which are concentrated in the microorganisms and suspended organic matter, which result in a disposal problem. (C) 2003 Published by Elsevier B.V.