The Research On Factors Of Affecting Sludge Adhering Behavior And Brief Analysis Of Sludge Adhering Mechanism

As the by-product of municipal sewage treatment, sewage sludge had brought to cities lots of environmental problems. First of all, although had been mechnically dewatered by filtration, sewage sludge still contented much water which caused problems in transporting, disposing and also in investment. It is necessary to dry the sludge to reduce its moisture content and volume. Sludge adhering behavior is a phenomena that sludge would adhere on the drying devices during sludge heat drying. It reduces the effect of heat transfer when drying the sludge and block the evaporation of water in the sludge and reduce the velocity of sludge drying and result in the waste of energy. At the same time sludge adhering behavior can affect the life of drying devices or destroy the devices directly.It discusses the effect of sludge moisture content on sludge adhering behavior with different conditions in this paper. And the effect of clarify of sludge(digested and undigested), drying methods(direct drying and indirect drying) and heat drying temperature on adhering behavior is also discussed. The result of the experiment shows that:Sludge moisture content is the most important factor affects the adhering quality. The change of adhering quality comply the rule that at the initial stage moisture content of sludge is high and adhering quality is small, then adhering quality increases as the moisture content decreases. Sludge adhering quality reaches to maxisum while the moisture content is about 60%. After that, the adhering quality decreases as the moisture content decreases. Sludge adhering quality is very small while the moisture content is about 30%.The effect of heat drying temperature on adhering quality is random, the temperature isn't a primary factor of affecting the adhering quality of sludge heat drying.Adhering quality of undigested sludge is more than that of digested sludge at each time of the heat drying process with different drying methods or different temperatures.Adhering quality of sludge dried indirectly is more than that of sludge dried directly.Also the mechanism of sludge adhering behavior is discussed in this paper. Adhering mechanism of gooey is used to explain that of sludge.