Unlocking Biodegradability: Pretreatment of Dairy Industry Wastewater by Hydrodynamic Cavitation.

The effectiveness of traditional biological treatment methods is frequently restricted by the high organic content and poor biodegradability of effluent from the dairy industry. Enhancing such effluents biodegradability before biological treatment might greatly improve treatment effectiveness and environmental compliance. By investigating its effects on the biodegradability index (BI) under different operating conditions, this study aims to determine the effectiveness of hydrodynamic cavitation (HC) as a method of pretreatment for dairy effluent. Orifice plates with different geometries were used to create hydrodynamic cavitation, and the procedure was run at various pH levels, temperatures, and inlet pressures. A total of seven orifice plate designs were tested. BI was calculated before and after treatment under each condition to assess the improvement in biodegradability. At an intake pressure of 2 bar, the highest improvement in BI was noted, rising from 0.34 to 0.58. At 1 bar, BI improved from 0.36 to 0.52, while pressures above 2 bar led to a decline in BI, establishing 2 bar as the optimal pressure Among the orifice plates, the configuration with three holes with 3 mm diameter resulted in the highest BI increase from 0.35 to 0.66. Additionally, operation at 30°C and pH 10 yielded the most favorable results in terms of biodegradability enhancement. Hydrodynamic cavitation has demonstrated strong potential as a pretreatment method for dairy wastewater, significantly improving its biodegradability under optimized conditions. This enhancement can contribute to more effective biological treatment and support sustainable wastewater management in the dairy industry.