Hydrodynamic cavitation‐ UV combined process of recirculating cooling water disinfection: Process performance, kinetics, data‐driven evaluation, and engineering applicability assessment

Abstract The combined process of hydrodynamic cavitation and ultraviolet (HC–UV) was evaluated for reducing culturable bacteria in industrial recirculating cooling water. Using cooling water collected from a power plant, laboratory experiments were conducted over throat diameters of 3–5 mm, inlet pressures of 0.2–0.4 MPa, and system temperatures of 20–40°C, with the UV power fixed at 20 W. Under the representative comparison condition of a 3 mm throat diameter, 0.3 MPa inlet pressure, and 20°C system temperature, HC–UV achieved 99.89% inactivation of culturable bacteria within 15 min from 3.62 × 10 4 CFU mL −1 , outperforming HC alone and UV alone. At 30 min, the observed log reduction exceeded the independent‐action expectation by 2.417 log units. Kinetic analysis showed nonlinear inactivation well described by a modified Weibull model with a residual term ( R 2 = 0.987). To further characterize multivariable coupling and temporal dependence, a convolutional neural network–long short‐term memory (CNN‐LSTM) model was developed using multivariate time‐series data. Among the four models, CNN‐LSTM yielded the highest R 2 and the lowest RMSE and MAE, with R 2 = 0.9598, RMSE = 0.0650, and MAE = 0.0416, supporting prediction and operating‐parameter evaluation within the investigated experimental range. In a representative pilot‐scale operation, the culturable bacterial count decreased from 3.96 × 10 5 to 7.0 × 10 3 CFU mL −1 , corresponding to a 98.23% reduction, with estimated energy consumption of 0.80 kWh m −3 and 0.46 kWh m −3 log −1 , excluding the submersible pump. These results provide preliminary evidence for the pilot‐scale applicability of HC–UV treatment in recirculating cooling water.