| Wastewater treatment is the head environment problem in our country. While we are doing wastewater treatment, we will face another difficult problem of sludge treatment. The residual activated sludge derived from petrochemical wastewater treatment plant contains not only inorganic matters, such as sulfureted hydrogen, heavy metal, halogen and their compound, but also organic matter such as hydroxybenzene, aldehyde, aromatic hydrocarbon, heterocyclic compound, and few water-fast oil matters. These sludge was more easy to pollute soil, groundwater and propagation, and more difficult treatment than ordinary municipal sludge.In this paper, influences of ultrasound on sludge anaerobic digestion were discussed basically. The water content of sludge is usually high, so the paper also examined influences of ultrasound on sludge dewatering. The application of ultrasound technology in wastewater and sludge treatment was hot. Ultrasound technology has a lot of advantages, such as moderate conditions, quick reaction velocity, broad application, and no pollution, and so on.In the sludge dewatering experiment, the paper studied the effects of cation poly- acrylamide (CPAM), ultrasound, and the combine of CPAM and ultrasound on sludge dewatering. The experimental results showed CPAM had good flocculation and sedi- mentation, but the CPAM dosage was much, and the sludge treatment cost was high. The combine of ultrasound and CPAM could improve sludge dewatering. At ultrasou- nd intensity of 470 W·m-2 for 2 min, the water content of sludge decreased from 97.2% to 81.3%, the sludge volume reduced 60%, the dosage of CPAM economized about 30%.In the sludge disintegration experiment, the paper studied detailedly the effects of ultrasound intensity, sonication time, ultrasound frequency, pyrogenation induced by ultrasound on sludge disintegration. The experimental results indicated ultrasound intensity and sonication time were two important factors on sludge disintegration, and...
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