Research On The Rheological Property And Drying Dynamic Of Dewatered Sludge

Due to development of industry and increase of population, the output of sewage sludge, as the by-product of wastewater treatment plants, has been increasing greatly. In order to prevent consequent pollution and make effective use of sewage sludge, sludge treatment and disposal has become one of the most important tasks for environmental protection. There are three sludge disposal methods, which are currently used, i.e. recycling in agriculture, land filling and incineration, and each of them needs to go through the drying technology. How to dry the municipal sludge economically and efficiently is a popular topic in the science field.Firstly the research is focused on the measurement of viscosity of dewatered sludge by trial-produced viscosimeter, then viscosity results can be used to decide that the sticky phase is about 54wt%-64wt% water content The changing characters of mass and lost-mass ratio versus temperature and heating time were investigated by differential thermal and thermal-gravimetric analysis (DTG) in the course of sewage sludge drying. And the drying course is explained by reaction kinetic, which assumes water is the production of drying, the apparent activation energy for drying can be obtained, and several analytical means show that the apparent activation of sewage sludge is approximate the drying decalescence of it, which is available of studying the drying character of dewatered sludge on the energy side.Based on experimental thermo gravimetric curves of cylindrical sewage sludge derived from a small-scale device, expression of water-loss rate and time can be gained according to the principal of isothermal reaction kinetic, from which we can see that linear relation between polynomial contains water-loss rate and drying time. The slope is decided by drying temperature and diameter of cylindrical sludge, we can draw their relation expression and test its exactness by experimental data. The slope computed by expression can estimate the drying time, which is important of researching sludge drying kinetic.