This paper describes biotreatability tests for treating a wastewater stream generated by wood-floorindustries after cleaning and washing of machinery used to apply urea–formaldehyde resins ontowood-fiber boards. A biological system consisting of an anaerobic – intermittently aerated reactor inlab-scale was constructed. Since the investigated wastewater is intermittently generated, the systemwas designed to operate in batch mode. The treatment focused on removal of formaldehyde and COD,as well as the efficiency of nitrification–denitrification. The proposed cheap and relatively simple-tooperatebiological system achieved COD and formaldehyde removal rates of 65 ± 11% and 93 ± 4% respectively.In spite of anaerobic ammonium removal and denitrification, the intermittently-aerated reactorshowed poor performance for nitrification. Therefore, a better understanding of constraints for the processimprovement is necessary. Regardless the constraints faced during the investigation, the proposedsystem can be considered feasible to partially reduce a great amount of biodegradable compounds inurea–formaldehyde-based wastewaters. However, to comply with strict threshold limits for industrialeffluent discharges, the use of biological treatment combined with more advanced processes is neededto achieve a better quality of the final effluent.This paper describes biotreatability tests for treating a wastewater stream generated by wood-floorindustries after cleaning and washing of machinery used to apply urea–formaldehyde resins ontowood-fiber boards. A biological system consisting of an anaerobic – intermittently aerated reactor inlab-scale was constructed. Since the investigated wastewater is intermittently generated, the systemwas designed to operate in batch mode. The treatment focused on removal of formaldehyde and COD,as well as the efficiency of nitrification–denitrification. The proposed cheap and relatively simple-tooperatebiological system achieved COD and formaldehyde removal rates of 65 ± 11% and 93 ± 4% respectively.In spite of anaerobic ammonium removal and denitrification, the intermittently-aerated reactorshowed poor performance for nitrification. Therefore, a better understanding of constraints for the processimprovement is necessary. Regardless the constraints faced during the investigation, the proposedsystem can be considered feasible to partially reduce a great amount of biodegradable compounds inurea–formaldehyde-based wastewaters. However, to comply with strict threshold limits for industrialeffluent discharges, the use of biological treatment combined with more advanced processes is neededto achieve a better quality of the final effluent.