Wastewater from kraft paper mills contains high concentrations of volatile fatty acids (VFAs), which contribute significantly to odour pollution and environmental degradation. Effective VFA removal is crucial for improving the quality of wastewater and minimizing its ecological impact. This study compares the performance of three aeration methods—mechanical aeration (MA), diffused air aeration (DAA), and combined diffused air and mechanical aeration (CDAMA)—for reducing VFAs, odour intensity, and key wastewater parameters such as chemical oxygen demand (COD), biological oxygen demand (BOD), and pH. A laboratory-scale aeration system (6-L capacity) was used to evaluate the treatment efficiency of each method. Among the methods tested, CDAMA achieved the highest removal efficiency, reducing VFAs, odour intensity, COD, and BOD by 65.9%, 70.59%, 72.14%, and 72%, respectively, indicating enhanced organic matter degradation. The combined approach improved oxygen transfer and microbial activity, thereby enhancing treatment performance. DAA demonstrated moderate success, with 62.12% VFA, 58.8% odour, 70% COD, and 69.94% BOD removal, although its performance was limited by lower mixing efficiency. MA showed the lowest efficacy, achieving 54.5% VFA, 53.5% odour, 66.3% COD, and 66.29% BOD reduction owing to its lower oxygen transfer capability. These findings confirm that CDAMA is the most effective aeration method, offering substantial improvements in VFA removal, odour reduction, and organic pollutant degradation. The study highlights the potential of optimized aeration strategies for improving wastewater treatment in the kraft paper mill industry, contributing to odour mitigation and environmental sustainability.