The aim of the study was to assess the course and efficiency of aerobic thermophilic treatment of a high-strength (COD = 35 9 O(2)/l) effluent from potato processing. A comparative analysis was conducted of the treatment effects achieved using batch, repeated-batch (with cell recycle and medium replacement) and continuous treatment operations. The analysis consisted in (I) examining the extent of removal for the major parameters of the wastewater: COD, TOC, TN and TP (chemical oxygen demand, total organic carbon, total nitrogen and total phosphorus), and (2) determining the impact of oxygen deficit on the formation and assimilation of organic acids in the course of the three treatment operations. When use was made of the repeated-batch operation, the values of the COD and TOC removal rates were more than twice as high as those obtained with the continuous process, and more than five times as high as those obtained with the batch process. (C) 2009 Elsevier Ltd. All rights reserved.