Research On Drying Characteristics Of Electroosmosis Dewatered Sludge

This research investigated the drying characteristics of electoosmosis dewateredsludge, and calculated the energy consumption of electroosmosis dehydration underdifferent conditions, so as to elect the dehydration type of the lowest energyconsumption. In addition，this research tried to make dewatered sludge under differentoperation conditions rewater, evaluated the drying characteristics of rewatered sludge,providing reference for the secongd drying of retwatered sludge.Through the drying experiments of electroosmosis dewatered sludge, thisresearch investigated the drying characteristics of electroosmosis dewatered sludgeunder different operation conditions, including voltage gradient, electroosmoticdehydration degree and drying temperature. The results show that electroosmosicdehydration is helpful to improve the drying rate of sludge, and the effects becomemore apparent along with the rising of volitage gradient, electroosmotic dehydrationdegree and drying temperature. The drying process of electroosmosis dewateredsludge only experiences warm-up period and reduction period, hardly experienceconstant speed drying period. The changes of drying sludge’s apparent characteristicsin drying process also have certain effects. The experiment shows that theelectroosmosis dewatered sludge under the actual voltage gradient of2.96V/mm anddehydration to the moisture content of67%have the best drying characteristics whenconstant temperature of105℃.The energy consumption calculation of the electroosmosis dehydration anddrying process shows that the average specific energy consumption of electroosmosisdehydration progress increases with the rising of volitage gradient and electricityosmotic dehydration degree. And the specific energy consumption of drying progressincreases with drying temperature’s rising. The dehydration progress with the actualvoltage gradient of1.97V/mm，dehydration to the moisture content of67%andconstant temperature of30℃has the minmum energy consumption among alldehydration progresses in the experiment.This research maked dewatered sludge rewater to simulate the situation ofdewatered sludge in damp ervironrment, and evaluated the drying characteristics ofrewatered sludge after mechanical dehydratin and drying treatment. The rewatered sludges are the original sluge，the original sluge with constant temperature of30℃drying and the electroosmosis dewatered sludge with the actual voltage gradient of1.97V/mm，dehydration to the moisture content of67%and constant temperature of30℃.The moisture content of rewatered after mechanical dehydratin are81.12%,75.72%,70.07%, respectively, being lower than that of machinery dewatered sludgein municipal sewage plant. Moreover, during the drying period of the moisture contentfrom20%to67%, the drying rate of rewatered sludge is higher than that of primarysludge and electroosmosis dewatered sludge with the actual voltage gradient of1.97V/mm and dehydration to the moisture content of67%. This shows thatelectroosmosis dehydration and drying treatment have irreversible damage effects onsluge’s structure, making the water binfing’s capacity of sludge weaker.