Study On Accoustic Sludge Reduction And Pollutant Removal Efficiency

In view of the problems such as the excess sludge,high treatment and disposal cost,it is very necessary to deal with it properly.If use sound waves can realize sludge reduction and increase the removal rate of pollutants,it will have great practical significance to reduce the cost of treatment and disposal,reduce the secondary pollution caused by residual sludge to the environment,apply the technology to the sewage treatment plants at home and abroad and promote the development of sludge treatment and disposal techniques in the future.It is found that the average value of the sludge concentration is 4501.81mg/Lin the control group,and the low concentration of the sludge is 4533.88mg/L under the effect of low frequency sound wave,therefore the results showed that the low frequency sound wave can not realize the sludge reduction effectively.While the average value of 7693.47mg/L in the control group,the average value of sludge concentration is 7446.82mg/L;The results showed that the sludge disposition can decreased by3.21%when the low frequency sound waves are in high sludge concentration environment.When use high frequency sound waves to explore the effect of sludge reduction,the results showed that the average value of sludge concentration is 4662.31mg/L in the control group while the high frequency sound wave under low sludge concentration,while the average concentration of the sludge is 4626.06mg/L in the high frequency acoustic wave group;Therefore,it is not obvious to use the high frequency acoustic wave on sludge reduction under the low sludge concentration condition.As for ultrasound,when the ultrasonic density is controlled at 1.0W/mL and ultrasonic time at 150s,sludge reduction effect is the best-12.16%.Compared with sound wave,ultrasonic reduction of sludge is more effective.Compared with the control group,the removal efficiency of low frequency acoustic wave on COD and TP was almost unchanged in low concentration environment,but the removal efficiency of NH₄⁺-N decreased slightly.When low frequency sound waves were in the high concentration sludge environment,the removal efficiency of COD,NH₄⁺-N and TP were not obvious.Compared with the control group,the removal rate of COD,NH₄⁺-N and TP were almost no difference between the high frequency sound wave and the low concentration or high concentration environment.As for ultrasonic wave,when the ultrasonic density is 0.5W/mL and ultrasonic time at 90s,120s,150s,the removal rates of COD,NH₄⁺-N and TP are 89.89%,86.84%,86.59%,90.78%,91.67%,92.01%,96.28%,96.06%,94.69%,while the removal rates of COD,NH₄⁺-N and TP are 90.64%,88.72%,.90.58%;91.92%,92.68%,93.60%;96.85%,96.34%,95.28%in the control group.When the ultrasonic density increases to 0.75W/mL and ultrasonic time at 90s,120s,150s,the removal rates of COD,NH₄⁺-N and TP are reduced by 3.02%,3.31%,1.74%,3.23%,2.71%,2.75%,0.88%,1.96%,1.77%respectively compared with 0.5W/mL.When the density of sound energy continues to expand to 1.0W/mL and ultrasonic time at 90s,120s,150s,the removal rates of COD,NH₄⁺-N and TP are reduced by 0.85%,0.20%,0.50%,0.23%,-0.77%,4.49%,0.46%,0.13%,-0.74%respectively compared with0.75W/mL.It can be seen that the enhanced acoustic energy density can not improve the removal efficiency of pollutants effectively.