Research On Drying Characteristics Of Electro-osmosis Dewatered Sludge

Sludge drying technology has become a key step for sludge treatment anddisposal, and sludge drying plays an increasingly important role in sludgemanagement system. Sludge thermal drying is the most widely using technology.However, high energy consumption has become a constraint factor of using sludgethermal drying technology. Electro-osmotic dehydration technology as a newsolid-liquid separation technology is gradually developed. If sludge moisture contentcan be cut down to a certain value by electro-osmosis dewatering, the required powerconsumption will increase dramatically. High energy consumption has also become aconstraint factor of using electro-osmosis dewatering. Electro-osmosis dehydrationand thermal drying technology can be used to dispose sludge, in any combination.This way could use the advantage of efficient separation attributed to electro-osmosisdehydration technology, and reducing energy consumption of the early thermal drying.But the researches of dewatered sludge drying and drying models are rarely studied.This paper tries to put electric dewatered sludge and sludge pre-processedwithout electro-osmotic dehydration as the research objects, when the initial moisturecontents of that sludge are similar, and sludge shear stress analysis and thecomparison and analysis of drying curves between sludge pretreated byelectric-osmotic dehydration or not are starting points to explore and analyze thedrying characteristics of sludge at different temperatures, in order to determineelectric dewatered sludge drying model, and establish energy computing applicationsof the sludge thermal drying-burning process and sludge electric dehydration-thermaldrying-burning process.The result shows that, electro-osmosis dehydration contribute to the reductionof sludge shear stress and the decrease of adhesion characteristics; In the early stagesof drying, sludge pretreated by electric-osmotic dehydration has faster drying ratethan sludge without electric-osmotic dehydration, but the distance between them willbe decrease with the process of drying; Drying rates of electric dewatered sludgewhose cathode surface upward or anode surface upward show larger gap in thepreheating and plateau zones, but in the decreasing rate zones of both curves havesimilar drying rates. No matter the sludge is preprocessed by electric dehydrationsludge or not, the performance of drying rates are similar under the40℃,60℃, but sludge pretreated by electric dehydration technology shows higher drying rate than thesludge pretreated without using electric dehydration, while the temperatures are80℃,100℃, and120℃. Logarithmic model and exploratory model MZ can be better fit fordewatered sludge and sludge preprocessed without using electro-osmotic dehydration,but the values of fitting parameter of exploratory model MZ show better. In addition,the energy of sludge thermal drying-burning process and sludge electricdehydration-thermal drying-burning process can be calculated by the energy-application software, under some certain condition.