Ultrasonic Treatment Of Biological Sludge To Obtain Carbon Source For Denitrification

Carbon source is a critical factor in biological denitrification. When the ratio of carbon and nitrogen is too low in wastewater, it must be applied carbon source to ensure the conduct of denitrification. In recent years, nitrogen content increase in urban sewage, it often occurs the problem of insufficient carbon source in biological denitrification. Approach to solve the question which need add carbon source in the sewage treatment process of low-carbon source in influent at home and abroad is dosing methanol, which increases operating costs. Sludge in wastewater treatment plant is rich in organic matter and energy, organic matter content as high as 60% ~ 70% in activated sludge particularly. With the increase of sludge in wastewater treatment plant in China, sludge production increased. The land filtration of large amount of sludge not only occupies land area, but also leeds to secondary pollution. It is very urgency to treat sludge with minimization, harmless, resource processing. In view of these facts, this paper studies the possibility of the organic matter in sludge as carbon source, while achieving sludge reduction, stabilization, resource.This paper investigated impact of the duty-cycle, sound energy density, the processing time and sludge pH value, temperature, concentration on ultrasonic treatment of sludge firstly. This is to optimize the ultrasonic extraction of sludge carbon source conditions. Studies have shown that the break rate of sludge increased with the increase of sound energy density; The time of the ultrasonic treatment is longer, the level of sludge break is higher; Effect of time of ultrasonic treatment is larger than energy density; In the same time of ultrasonic cell pulverizer work, SCOD(soluble chemical oxygen demand) in the supernatant of sludge and break rate of sludge increased with the increase of the duty cycle; The pH value affect of ultrasonic treatment of sludge, it can significantly improve the break effect in alkali conditions; Increase of sludge temperature when sludge treat by ultrasonic, will help break the cell; It can get more organic matter when take the high concentration of sludge to treat by ultrasonic.Studies on the components of the sludge supernatant after ultrasonic treatment have shown that organic matter content increased in supernatant; while soluble chemical oxygen demand increased, total nitrogen and total phosphorus also increased; After processing time of 40 minutes, the average of ratio of SCOD and TN was 18, bigger than the C/N ratio of biological denitrification required; The average of ratio of SCOD and TP was 70.45; nitrogen and phosphorus were suitably recovered by struvite precipitation. At the same time studied the changing of the nature of sludge mixture was found sludge particle size decreased; sludge temperature rise; sludge mixture pH value decreased when sludge have been treat by ultrasonic.Studied the effect of nitrogen removal when use the supernatant after ultrasonic treatment of sludge as a carbon source in biological denitrification in two bioreactors (Sequencing batch bioreactor, Biofilter). Studies have shown that when carbon is sufficient, it has a good nitrogen removal, but at the same time it will give the system additional nitrogen and phosphorus. So conditions are restricted to use such carbon sources.