The reduction of waste sludge in SBR by ultrasonic treatment

A new process for reduction of waste sludge by ultrasound has been demonstrated. In former studies, ultrasound was mainly used for dehydration of waste sludge. Otherwise, it has been reported that ultrasound could efficiently provide a chance for excess sludge removal in reactor directly. Therefore, ultrasound was suggested to reduce waste sludge in SBR reactor in this paper. The results showed that ultrasound was used to reduce sludge produced in Sequencing Batch Reactor (SBR, in short), and the generation of sludge was just 2.5 mg/L·d in average, the excess sludge yield in SBR was increased much lower than that in SBR with excess sludge untreated. Moreover, the influent COD was reduced from 600 mg/L to 59 mg/L under the condition of ultrasonic intensity 1.5 W/mL, ultrasonic time 15 min, reflux ratio 5:16. The effluent COD could achieve one-degree emission standard based on the contamination emission standard for urban waster water treatment plant of China (GB18918-2002).