Industrial Pollutants: Heavy Metals and Their Salts

Introduction Heavy metals and their salts (Cu, Zn, Hg, Pb, Co, Ni) are widely used industrial pollutants. In the waters they come from natural sources (rock surface, soil and groundwater), and waste water and sediments from many industrial companies, which are contaminated by smoke emissions. Heavy metals are often encountered as trace elements in natural water and water. It depends on significant changes in geochemical conditions. Heavy metals are very stable.

One of the main causes of waterborne heavy metal contamination is release of heavy metal ions including industrial waste to water sources. This is usually a direct result of inefficient treatment of the heavy metal removal process. The occurrence of aquatic pollutants (such as heavy metals) is related to changes in the immune system of fish and the incidence of infections. Water is immersed in waste such as pollutants and heavy metals. All toxic substances reaching dangerous levels are heavy metals (Regine and Volesky, 2000). Even certain heavy metals at very low levels can have a significant impact on the structure and function of the immune system, which is about as harmful as the direct toxicity (Saxena et al., 2009).

Water heavy metal contamination is a serious environmental problem that modern society faces. Worldwide, heavy metal contamination is increasing in the environment due to an increase in the number of industries (Chidambaram et al., 2009). Industrial wastewater is discharged into sewage, river and irrigation water, which causes serious pollution and health damage (Baddesha and Rao 1986). Many industrial wastewaters contain heavy metals such as cadmium, lead, zinc, cobalt and chromium. The most toxic heavy metals are absorbed and accumulated as free metals in various plant parts. This may adversely affect plant growth and metabolism (Barman and Lal 1994). When these metals are incorporated into the food chain, people and cattle are seriously affected to cause bronchitis and cancer (Khasim et al., 1989; McGrath and Smith, 1990; Nath et al., 2005) . Among the heavy metals, chromium plays an important role in polluting our water environment system.

Over the past two decades, people have paid great attention to the management of environmental pollution caused by harmful substances such as heavy metals. Purification of heavy metals in soil and water around industrial plants has long been a problem. Numerous methods have been developed for removing heavy metals from liquid waste, such as precipitation, evaporation, electroplating, ion exchange, membrane processes, etc. However, these methods are processes representative of unpredictable metal ion removal, high reagent requirements, and biotechnology innovation, such as a cost-effective and excellent tool for removing heavy metals from aqueous solutions It has disadvantages.