Recently, the existence of toxic materials in our environment has caused severe concern to the living organism. The main causes for the contamination of such toxic materials in the environment are rapid industrialization and agricultural activities. The different toxic entities present in the environment mainly depend on the nature of the industry. However, some of the common generated toxic pollutants present in the water bodies are heavy metal ions, phenol, dyes, pesticides, insecticides, detergents, and a wide spectrum of aromatic compounds. Among those substance, heavy metals have been reported the major one for the last few decades. So, these heavy metals must be removed from the environment by proper techniques to save the society. The chapter deals with the different toxic material removal technologies and mathematical modeling.
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Arsenic, cadmium, copper, chromium, zinc, lead, nickel, mercury, etc. are such type of heavy metals which have lethal effects to the living beings. Due to its non-biodegradability nature and tend to accumulate in living organism, thus enter into the food chain. The concentration of such type of toxic heavy metals in the water bodies must be reduced and the industries are advised to treat their effluents before discharged to acceptable level into the environment.
Arsenic is one of the important toxic heavy metal that contaminated in water, especially groundwater. It has been recognized as a major water pollutant. The main source of arsenic in the environment from smelting, rock sediments, energy production from fossil fuels and mining industries etc. The toxicological effect of it in the living beings are gastrointestinal symptoms, bone marrow depression, disturbances of cardiovascular and nervous system functions, hepatomegaly, hemolysis, melanosis and liver tumor etc. So it is very important to eliminate from our environment.
U.S. Environmental Protection Agency classified that cadmium is a probable human carcinogen. It is entered into the environment from refining, mining, pigments, plastic, alloy manufacturing, smelting and electroplating industries etc. The discharged cadmium in effluent absorbed and accumulated by microorganisms. Eventually, it is transferred to living beings through food chain. It causes Itai-Itai diseases, renal disturbances, lung insufficiency, bone lesions, cancer, hypertension, weight loss etc.
Catalytic activity of a number of enzymes is controlled by copper. But it is toxic when deficient or in excess in the living beings. Electronics plating, printed circuit board manufacturing, copper polishing, wire drawing, paint manufacturing wood preservatives and printing operations industries are the main source of copper in wastewater. Excessive copper accumulation causes neurotoxicity, reproductive and developmental toxicity, acute toxicity, dizziness and diarrhea etc.
Chromium exits mainly trivalent and hexavalent oxidation states in the aqueous solution. Microorganism accumulates trivalent chromium as an essential trace metal nutrient but hexavalent state is a great concern because of its toxicity. The major source of hexavalent chromium are leather tanning, electroplating, metal processing, textile dyeing, paints and pigments, wood preservatives, steel fabrication and canning industries etc. It is reported as carcinogenic, teratogenic, mutagenic, epigastric pain nausea, vomiting, severe diarrhea, producing lung tumors etc.
Zinc is a micronutrient, essential for physiological and biochemical processes of living tissue. It enters into the water bodies from mining and manufacturing process industries. Too much concentration of zinc causes gastrointestinal distress, short term ‘‘metal-fume fever”, diarrhea, nausea, etc.
There is large number of non-biodegradable toxic heavy metal existing in our environment but lead is one of the them which enter into the living being through the food chain. It damages brain, causes anorexia, anaemia, malaise, loss of appetite, diminishing IQ etc. The main source of this toxic heavy metal in the environment is battery manufacturing, electroplating, ammunition, pigments industries etc.
Trace amount of nickel is required for humans and animals but medical science reported that in excess concentration it can be very toxic, even carcinogenic. Nickel containing effluents enter in the environment from electroplating, paint formulation, mineral processing, non-ferrous metal, porcelain enameling, copper sulphate manufacture and steam-electric power plants industries etc. Lung cancer, chronic bronchitis, reduced lung function etc. are caused by the toxic effect of nickel.
One of the highly toxic heavy metal in our environment is mercury. It has high tendency to effects the neurological and renal disturbances, kidney damage, impairment of pulmonary function, corrosive to skin, eyes, muscles etc. Once mercury enters into the food chain, it accumulates into the humans and animals. Minamata disease was caused by mercury pollution in Japan (1953-1960). The most toxic species are, however, organic mercury, especially CH3Hg+ as it is soluble in fat, lipid of membranes and brain tissue. The main source of this toxic heavy metal are volcanic eruptions, weathering of mercuriferous areas, battery production, naturally-caused forest fires, mining and metallurgical processes, fossil fuel burning, biogenic emissions, paint and chloralkali industries etc.