Advanced Technologies for Treating Highly Concentrated Dairy Industry Wastewater

The adoption of water-saving technologies in dairy industry facilities has created a challenge in effectively treating their high-strength wastewater. One approach to addressing this issue involves the implementation of integrated treatment technologies. This study aimed to identify the most effective wastewater pretreatment solutions for discharge into municipal sewer systems or natural water bodies. We analyzed current methods and technologies for treating high-strength effluents generated by dairy plants, proposed, and experimentally validated the performance of a custom-designed aeration-settling tank with increased hydraulic height and jet aeration for use at dairy wastewater treatment facilities. For high-strength effluents with chemical oxygen demand (COD) values ranging from 2000 to 5000 mg/dm³, where discharge into municipal sewer systems is intended, the proposed technology and proprietary infrastructure proved suitable. These include flotation-settling tanks and aeration-settling tanks with increased hydraulic height (6–10 m) equipped with surface jet aeration. When discharging into natural water bodies, a two-stage biological treatment process is necessary, utilizing the same aeration tank configuration followed by post-treatment through polystyrene-based filtration systems. Field testing of the proposed system demonstrated its capacity to increase the concentration of activated sludge in the aeration zone to 5–6 g/dm³ and to efficiently separate sludge mixtures. This results in high oxidative capacity of the treatment infrastructure, with COD removal rates reaching up to 2200 g/(m³ day), and enables effective nitrogen compound removal via simultaneous biological nitrification−denitrification. This is achieved by forming an aerobic zone in the upper part and an anoxic (anaerobic) zone in the lower part of the unit. The authors also investigated the flocculating and disinfecting properties of polyhexamethylene guanidine salts, confirming their applicability at various stages of wastewater treatment. These compounds neutralize potentially harmful microorganisms, promote the sedimentation of suspended solids, and eliminate residual odors and coloration. Based on these findings, the authors propose a treatment technology for high-strength dairy wastewater (COD 2000–5000 mg/dm³) that combines physical and biological methods. This integrated approach ensures efficient treatment before discharge into either municipal sewer systems or open water bodies.