[Experimental research on indirect thermal drying process of sewage sludge]

Technical parameter, condensed steam water quality and flue gases were studied and organic compound hydrolysis mechanism was discussed. During experimental study, observed that the relationship between water content of sewage sludge and residence time have a negative exponential function. The condensed steam water has a high-concentration organic content. Total organic carbon (TOC), volatile fatty acid (VFA) and NH3 -N of the water were very high and the pH value was between 9 and 9.5. VFA and NH3 -N come from two sections: (1) In the 110 - 130 degrees C temperature range, hydrolysis of protein occurred with the formation of VFA and NH3 -N; and (2) In the 140 - 150 degrees C, fats hydrolyzed into VFA. There was no gaseous pollution produced in the whole experimental progress.