DESIGN AND OPTIMIZATION OF A SYSTEM FOR SLUDGE DEWATERING AND INCINERATION.

摘要

Vacuum filtration was adopted as a basis for studying sludge dewatering. The importance of operational and equipment variables in the vacuum filter operation was analyzed and tested at the Amherst Wastewater Treatment Plant using their in-process sludge.; Mathematical models were developed which predicted the solids yield rate with an accuracy of (+OR-) 2.8 percent. The sludge cake dryness followed the mathematical model and was found to exhibit a semi-logarithmic relationship with the cake drying time and the cake weight per unit area per revolution.; Cationic polymers such as Stockhausen 536K, 334 KKS, and Nalco were found to be effective for sludge conditioning. EIMCO polypropylene filter media POPR-929, POPR-852F, and POPR-854F gave a relatively higher filtration rate, a drier cake, and a better filtrate clarity than that did other filter media.; The capillary suction time technique was proven to be inexpensive, accurate, and quick in determining polymer types and doses, and could be used to replace the traditional Buchner Funnel Test. The specific resistance of the sludge could be related to the corresponding CST by using an established curve.; Co-dewatering of the sludge by adding pulverized coal provided a technically feasible and economically viable process for disposing of the dewatered sludge by incineration. Coal served as a dewatering aid for vacuum filtration and, because it is an excellent fuel, it also served as the supplemental fuel for sludge incineration. Coal additions increased the net sludge solids yield and imposed no additional solids burden on the vacuum filter. Coal additions at a coal-to-sludge ratio of approximately one increased the cake dryness from 12.7 to 22.2 percent solids, which was over the self-sustaining point of combustion. In addition, the heating value of the filter cake substantially increased due to the higher cake solids content and the high calorific content of the added coal. Besides, the filtrate quality slightly improved without additional chemical conditioning and the sticking tendencies of the sludge were reduced which promoted cake release and discharge.; An economic analysis indicated that an annual energy savings of approximately {dollar}191,000 could be realized for the Amherst Wastewater Treatment Plant by employing the co-dewatering technique. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI