CHARACTERISTICS RESEARCH OF SLUDGE MICRO-BUBBLE DRYING AND DERIVED FUEL

At present, incineration method is one of important means of sludge "four-disposal principles (reduction, stabilization, harmlessness and resource), which is rarely applied in sludge landfill. However, the existing problem is high water content of sludge resulting in high drying cost and unsatisfactory burning effect. In this study, a foaming agent (sodium lauryl sulfate, SDS) was employed for micro-bubble drying of the sludge and pulverized coal was added as the combustion supporting material, further researching change of water content and heat value in the process of sludge foaming. The properties of sludge-derived fuel were analyzed by X-ray diffraction and thermogravimetric techniques. The results show that suitable introduction of foaming agent (SDS) improves the formation of micro-bubble structure of sludge, enhances the water evaporation area in interior of the sludge and facilitates the contact between pulverized coal and sludge particles as well as greatly promotes the heat of combustion for sludge drying and mixture of coal and sludge. Moreover, when SDS/sludge (g"g-1) is 0.25, water content of dewatered sludge is decreased from 77.9% to 55.1% and low heat value of the sludge derived fuel increases by about 47%. In addition, the result also shows that the weight loss ratio is positively correlated with the low heat value of the fuel, that is to say, the adding of SDS improves the low heat value, thereby, promoting the reducing quantity of the fuel in a certain control range of temperature.