Ultrasonic-acidification coupled backwash-mixing technology in wastewater filtration system: Determination and...

A filtration system is crucial for recycling wastewater, with the filter as its core component. However, traditional filters struggle with rapid cleaning due to wastewater complexity, which challenges the sustainable operation of filtration systems. This study proposes a new method of mixed ultrasound assisted acid backwashing, however, the optimal cleaning parameters for this method are not yet clear. We evaluated the effects of various cleaning factors on filter cleaning parameters using single factor and response surface experiments. We evaluated the effects of ultrasound, acid washing, and backwashing, both individually and in combination, on filter performance, assessed by hydraulic performance recovery (HPR) and dirt removal rate (Drr). The results showed that backwashing yielded the best Drr (80.34 %), acid washing achieved the highest HPR (96.03 %) at low pH, and ultrasound demonstrated superior overall performance, improving HPR by 4.6 % over backwashing and Drr by 23.45 % over acid washing. The combined method enhanced cleaning efficiency, achieving complete recovery in some cases and increasing Drr by up to 28.44 %. Key cleaning parameters-ultrasonic duration, backwash time, and pH, were identified as most influential, and a response surface model was developed to optimise them. This study demonstrates the synergistic effect of ultrasound and acidic backwashing, providing a novel approach to improving filter cleaning and advancing the integration of acoustic energy in wastewater treatment systems.