Pilot Study On Alkali Ultrasound Sludge Reduction

The treatment of sewage sludge is an important part of biological treatment process. Due to the high cost of terminal treatment, source reduction is very important. Our research group found that in the sludge lysis process, low energy density of ultrasound on the penetration of alkali to the sludge has a very good role in promoting, maintaining a cost-lysis. It provides an effective way for the source of the sludge reduction. Based on previous laboratory studies, we established a sewage treatment capacity of 400 m3/d of CAS system with the alkali ultrasonic technology. The system's treatment capacity of concentrated sludge is 2 m3/d and alkali dosage is 1.97 g NaOH/L sludge. The pH of sludge after the alkali dosing is about 11.9. After three section of 20 Hz, 400 W of ultrasonic treatment, the sludge's SCOD dissolution value is ranges from 270 mg/L to 2600 mg/L and the increases SCOD is about 2300 mg/L. The lysis of alkaline ultrasound system is in the rate of 15%. Liquid TN, ammonia nitrogen, TP has a greater release.In the first 8 hours of acidification, the pH of the sludge was declined sharply and after 40 hours this trend leveled off in a stable phase of acidification. The sludge's BOD/COD value changed from 0.17 to 0.21 after acidification. It indicated that acidification increased the biodegradability of sludge. Meanwhile, the amination reaction could get a good result in the process of hydrolysis and acidification,Excess sludge reduction process based on the lysis growth could be realized by recycling the acidified sludge back to the aeration tank. The CAS treated sewage 400 m3/d, the amount of the whole system's sludge emission was 10.68 m3/d (the concentration is 8.09 g/L), discharged sludge 86.40 kgSS a day. Net plus sewage sludge of Jizhuangzi, the actual effect of sludge reduction was 60.2%.The test results also showed that the alkali ultrasound system released a mount of TN, TP, COD and other substances. They increased the burden on activated sludge treatment system and together with inclined tube sedimentation tanks in the running for some time after the treatment effect decreasing, the effluent water quality became deteriorated. But, overall, the water quality of the system was normal. The effluent water quality of Alkali ultrasound systems includes SS, TN, ammonia nitrogen, pH and other indicators were good and could comply with the Class A of the national standards for effluent discharge level.