Study On Enhancement Of Sludge Dewaterability Using Microwave Combined With Flocculation

As countries in the world to strictly control sewage discharge standards and at the same time strengthening the sewage treatment,the increase in sludge production and the environmental pollution have become the focus of environmental protection.Nowadays,the key problem of sludge disposal is how to efficiently remove the moisture which accounts for the majority of the excess sludge weight in the wastewater treatment plant.This paper is based on microwave technology and flocculant conditioning technology,and through the study of the combined use of both on sludge dewatering performance,to explore more effective sludge dewatering technology.In this paper,under the premise of microwave treatment,different kinds of flocculants were added to study the improvement of sludge dewatering performance.By comparing the pretreatment of different power and time of microwave chemical reactor and the dosage of different flocculants,then find PAC is the best flocculant.By researching single factor variables such as Microwave power,Microwave processing time,Drug dosing quantity and the initial pH value,to Explore the factors affect the performance of sludge dewatering,and through the orthogonal experiment to further determine the influence of various factors on the performance of sludge dewatering order:dosage of PAC>Microwave power>Microwave processing time>PAC processing time.In the meantime found under the best conditions of sludge dewatering performance can be significantly improved,the higher the microwave power,the shorter the time required to reach the optimal dehydration conditions,the better the effect.The experimental result shows the best combination of microwave and PAC is that dose 0.25g PAC per 100ml sludge,fewer minutes later,heat the sludge 15 second under microwave whose power is 650 watt,after cooling to Room temperature,then start to test the SRF and the moisture content of the sludge cake,the combination can significantly improve the sludge dewatering performance,compared to the original sludge,the moisture content decreased by 21.95%and the SRF decreased from 2.95 X 1012m/kg to 0.35 × 1012m/kg,decreased by 88.1%.To further analyze the mechanism of the combination of microwave and PAC,this study also explored the effect of Zeta potential,the flocculate structure in sludge,and the composition of the EPS on sludge dewaterability.lt was demonstrated that there's link between dewaterability and Zeta potential.When microwave whose power is 650W combined with PAC,the average of |?| was 0.90mv.The ? potential of the sludge particles declined compared to original sludge,thus improving the sludge dewatering performance.On the other hand,When microwave combined with PAC,The average value of fractal dimension(D2)of sludge also increased,the higher power of microwave,the larger fractal dimension(D2),when 650 watt microwave combined with PAC,the average value of fractal dimension(D2)of sludge increased from 1.25 to 1.55,which indicated that the sludge dewatering performance was related to the sludge floc structure.The more dense the sludge floc was,the smaller the sludge particle clearance was,the better the settleabilityof sludge and the dewatering rate of sludge was.After co-conditioning of microwave and PAC,the contents of EPS and LB-EPS in sludge reduced considerably,and the ratio of LB-EPS/TB-EPS reduced as well.The contents of LB-EPS was related to the flocculation capability of sludge,the ratio of LB-EPS/TB-EPS was also related to the degree of sludge dewatering,thus can prove that the reduction of the contents of LB-EPS and the ratio of LB-EPS/TB-EPS was beneficial to enhance sludge dewaterability.