การรั่วไหลของโลหะหนักจากก้อนหล่อแข็งของเสียที่เตรียม โดยการกระตุ้นเถ้าแกลบดำด้วยด่าง

Abstract

       This paper investigated leaching of heavy metals from the solidified wastes using black rice husk ash and hydrated lime as solidification binders at the ration of 55:45. Sodium silicate solution containing SiO₂ and Na₂O at the mass ratio of 3.0 was used to activate the pozzolanic reactions at 1.5 wt.% of the binders. Heavy metal sludge was added at 0, 30 and 50% by weight of total solid. Release of heavy metals from the solidified wastes was done by extraction with synthetic acid rain having an initial pH of 3.0 and extracted for 10 times. Experimental results showed that pH of the synthetic acid rain after each extraction from the solidified wastes without and with sodium silicate solution increases to be in the range of 12.44 - 11.68 and 12.42 – 11.47, respectively. In addition, heavy metals release was found to increase when the amounts of heavy metal sludge in the solidified wastes increase. Cumulative concentrations of Cu, Fe, Pb and Cr released from the solidified wastes activated with sodium silicate solution and containing 30 and 50 wt.% of total solid were 0.22, 2.10, 1.13, 0.54 mg/L and 0.29, 2.13, 1.20 และ 0.68 mg/L, respectively. However, the cumulative concentrations of heavy metals in the leachate extracted from all samples for 10 times were not exceeding the regulatory limit of the Ministry of Industry.