Chemical synthesis processes of the pharmaceuticals industry produce wastewaters which are variable in character and highly strong. In-plant controls are important and highly effective in determining the final wastewater quality. At any rate several stages of treatment comprised of physical, chemical and biological are required to obtain a reasonable degree of treatment. The problem is further complicated in small-scale plants due to low volume of wastewaters and dilution requirements. In this study, a small-scale pharmaceuticals plant producing three common active materials was experimentally evaluated to assess the waste management alternatives. The processes were evaluated and a source-based pollution profile was prepared. Paracetamol wastewaters were found to be readily biodegradable. Omeprazole wastewaters could be biologically treated only after significant chemical treatment. Mephenoxalone wastewaters were in no case biologically degradable. Paracetamol and pretreated Omeprazole wastewaters could be biologically treated down to several hundreds of ppm COD at as high as 0.5 g COD/g VSS day F/M ratio after several fold dilution. Results of the study were evaluated and discussed. (C) 1999 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reserved.