Nitrate and the selected pesticides, trifluralin, fenitrothion and endosulfan (alpha + beta) removal was studied in an up flow biological denitrification reactor packed with wheat straw as carbon source and support particles for microorganisms. A high removal efficiency was observed for the selected pesticides and nitrate in the biological denitrification continuous reactor. During the continuous study, 23.4% of the initial weight of wheat straw was lost and 24 g was exhausted per gram of nitrogen removed. Adsorption capacity of wheat straw was determined by batch column experiments and compared with activated carbon (AC) adsorption under similar conditions. In order to remove colour, dissolved organic carbon (DOC) and nitrate from the water, activated carbon adsorption studies were performed in a batch unit. (C) 2004 Elsevier Ltd. All rights reserved.