Application of waste ashes to agricultural land } effect of incineration temperature on chemical characteristics

Incineration is one of the most important methods of municipal waste disposal. During incineration, various reactions of composition and decomposition may occur; the physical and chemical properties of municipal wastes may change to a great extent. In the present study, 15 samples, including food scraps FS., animal wastes AW. and sewage sludges SS. were collected from various places in Japan, incineration treatments at 5008C, 8508C and 10008C were conducted in laboratory, and pH, EC, P content, various P forms, anions and soluble metals were determined. The results indicated that average pH increased by 1.09, 1.84, 2.27 and EC decreased by 4.6, 4.6, 5.6 ds my1 at 5008C, 8508C, 10008C, respectively, pH increased in the sequence of AM)SS)FS, and the decrease rate of EC was in the order of FS)SS)AM. Compared with no treatment NT., water-soluble P decreased greatly at all three temperatures; available P increased at 5008C, but decreased to the original level at 8508C and 10008C; the amount of Ca-P, Fe-P and Al-P decreased and residual insoluble P increased greatly at 8508C and 10008C; no significant change of total P was found at all three temperatures. However, water-soluble HPO42y and Cly decreased greatly, the decrease ratio of Cly was in the sequence of SS)FS)AM at 5008C, and FS)SS)AM at 8508C and 10008C; no significant difference was found for HPO42y among all three treatment temperatures; water-soluble SO42y decreased at 10008C, but there was no significant change at 5008C and 8508C. Moreover, water-soluble Na, Mg, K, Ti, Mn, Fe, Ga, Cd, Zn, Ba, Pb, Sr, W and 0.1 M HNO3 soluble Al, K, Cr, Mn, Fe, Zn, Sr, Ba, Pb, Be, Ga, Rb, Cd, Sn, Sb, Ta, Tl, Bi, Na, Co, Ni, Sc, Cs decreased, but water-soluble Ca, Cr, Co, Ni and 0.1 M HNO3 soluble Cu, Ca, V, Mo, W, Th, U, Hf increased at 5008C, 8508C or 10008C.