3. Identification of input raw materials and design of appropriate ratios of mixing
The selected input neutralization sludge (NS) belonged to hazardous waste (HW) with designation A, B and C.
Hodul [3] characterized NS as a waste arising after neutralization of waste acids from various industrial processes
that contain hazardous substances. These selected NS are produced because of the process of the surface treatment
of steel materials as by-products. Al-Tabbaa and Perera [2] and Hodul [3] reported that for purposes of the
classification of their negative effects on the environment the leaching test, the determination of the concentration
of pollutants in the dry and also determination the dry matter content must be carried out. NS-A (Fig. 2 (a))
showed high concentrations of dissolved solids in an aqueous extract (5250 mg/l) and aqueous extracts of NS-B
and NS-C contained about 3000 mg/l dissolved solids (Table 1). Leachate pH of all the NS ranged from 9 to 11.
None of the NS have exceeded the parameters corresponding to the leachability class IIa according to Regulation