Immobilization of Heavy Metals in Industrial Waste by Solidification/Stabilization Methods

Abstract

          Heavy metals are essential in many manufacturing processes such as production of automotive batteries, chloralkali, and fluorescent lights. As a result, industrial wastes containing heavy metals can create problems to the environment and human beings because of their indestructible nature. Heavy metals can easily enter the food chain and continue up ultimately affecting human beings (Valenti, 1992, Okrent and Xing, 1993). Many kinds of heavy metal can cause the development of different types of cancers. For example, arsenic, nickel, cadmium, chromium, and beryllium can increase the risk of lung cancer in humans. In addition, the ingestion of inorganic arsenic compounds has been shown to increase the risk of skin cancer in human beings. Furthermore, the exposure of humans to the oxide of cadmium has been shown to increase chances for development of prostate respiratory, and genito-urinary cancers (Okrent and Xing, 1993)          Unlike the preceding toxic metals, mercury will not cause cancer, but will induce the development of “Minamata disease”, which occurred during the 1950s in Japan. Furthermore, mercury can cause central nervous system disorder, numbness, impaired speech, paralysis, oleformity, coma and death (Chang et al., 1993).          Because of the release of heavy metals into the environment, it has become necessary to develop and implement suitable procedures for the treatment of heavy metal-bearing wastes prior to disposal. There are many common processed for the treatment of heavy metal wastes such as cheating by the strong binding compound, trimercapto-s-triazine (Ayoub et al., 1995), acid-extraction treatment system (Kastanek et al., 1994), and solidification/stabilization (Chang et al., 1993 and Twidwell et at., 1994). The latter method is the most common one used to prevent heavy metals from leaching into the environment.