Study On Excess Sludge Treatment By Coupling Fenton And Ultrasonic

Sewage sludge is a byproduct of the biological treatment process and it has high moisture content, complex components. How to find cost-effective treatment and disposal of sludge has become a widespread concern of all parties.In the process of sludge reduction dispose, in order to exploit a simple and efficient method of sludge disintegration, a series of experiments study the efficiency of disruption of excess sludge by Fenton, low-frequency ultrasonic,Fenton synchronous coupled with ultrasound and the different coupling manners of Fenton with ultrasound.The experiment results of Fenton oxidise excess sludge show that when the intial p H is 3, the dosage of Fe2+is 0.8g/L, the dosage of H2O2 is 10g/L and the reaction time is 1h, the increases of SCOD, NH3-N, TP are 29.4 times, 28.8 times and 4.9 times higher than the sludge before reaction respectively, it has a high degree of sludge disintegration. MLVSS / MLSS declines 27.9% of the sludge before reaction, the degree of sludge stabilization gets raised. When not adjusting the p H, the dosage of Fe2+ is 0.8g/L, the dosage of H2O2 is 10g/L and the reaction time is 1h, CST declines 57.58% compared with the sludge before reaction, and sludge dewaterability is significantly improved obviously.The experiment results of which ultrasound affect on Fenton crack sludge show that when the pulse ratio is 4:1, the energy density is 0.08W/m L and the reaction time is 60 min, the degree of sludge disintegration is higher. The increases of SCOD, NH3-N, TP are 36.9 times, 33.4 times and 7.3 times higher than the sludge before reaction respectively. The ultrasound has little effect on MLVSS/MLSS and no acceleration to sludge stabilization. CST are increasing with the pulse ratio, energy density, reaction time enlargement, along with thesludge dewaterability deterioration.The result of analyzing solubility index, EPS and sludge microstructure shows that the degree of sludge disintegration by Fenton synchronous coupled with ultrasound is better than ultrasound or Fenton alone. In the process of sludge disintegration, MLVSS/MLSS values of the sludge treat by ultrasound method,Fenton method, Fenton synchronous coupled with ultrasound and the sludge before treatment are 0.433, 0.310, 0.312, 0.430, respectively. It indicates that Fenton method and coupling method have function on sludge stabilization, the ultrasound method has basically no effect on sludge stabilization. SV30 of the sludge treat by ultrasound method, Fenton method, Fenton synchronous coupled with ultrasound and the sludge before treatment are 90%, 76%, 86% respectively,having some improvement compared with the original sludge settle ratio of 94%.And the sludge settling only after ultrasound is the best. Comparing with the original sludge, Fenton method helps to enhance the sludge dewaterability,coupling method has little effect on the sludge dewaterability and the ultrasound method makes the sludge dewaterability worse.Three different coupling ways of US+Fenton, Fenton+US and sync method all have a strong effect on sludge disintegration and have small differences among different ways. Different coupling ways have mainly no effect on the content of organic matter in the sludge. After three coupling ways of US+Fenton,Fenton+US and sync method treating the sludge, MLVSS/MLSS are 0.308, 0.310,0.312 respectively. They all have significantly reduced comparing with the original sludge MLVSS/MLSS value of 0.430 and have a great improve on sludge stabilization. In the process of sludge disintegration, the total amount of EPS released into the supernatant are US+Fenton, Fenton+US, sync method from high to low and they are 241.67 mg / L, 216.29 mg / L, 186.78 mg / L respectively.It reflects that US+Fenton method is the best way to crack extracellular polymeric substance. After treating by US+Fenton, Fenton+US and sync method,SV30 of the sludge are 55%, 77%, 86% respectively, having a great improvement compared with the sludge before treatment and the settling of the sludge treating by US+Fenton is the best. The dewaterability of US+Fenton and sync method are similar, and CST are highter than the original sludge. They have no effect on improving sludge dewaterability. Fenton+US would make the sludge dewaterability deteriorate.