AUTHOR: EMEL KILIÇ –CHEMICAL ENGINEER ( HACETTEPE UNIVERSITY)
CHEMICAL DIVISION MANAGER – CAG KIMYA TURKEYHEAVY METALS POLLUTION IN WATERGenerally the water pollution is described as the presence in water of enough harmful or objectionable material to damage the water's quality.
Common Metals and their sources
THE EFFECTS OF HEAVY METALS TO HUMAN HEALTHHeavy metals are natural components of the Earth's crust. They cannot be degraded or destroyed. To a small extent they enter our bodies via food, drinking water and air. As trace elements, some heavy metals (e.g. copper, selenium, zinc) are essential to maintain the metabolism of the human body. However, at higher concentrations they can lead to poisoning. Heavy metal poisoning could result, for instance, from drinking-water contamination (e.g. lead pipes), high ambient air concentrations near emission sources.
Heavy metals can enter a water supply by industrial and consumer waste, or even from acidic rain breaking down soils and releasing heavy metals into streams, lakes, rivers, and groundwater. Now we are going to describe the kinds of heavy metals, their dangerous levels and the effects of these heavy metals to human health and environment. The most pollutans heavy metals are Lead, Cadmium, Copper, Chromium, Selenium and Mercury.Lead In humans, Long term exposure can occur acute or chronic damage to the nervous system on humans. Cadmium In humans, long-term exposure is associated with renal disfunction. High exposure can lead to obstructive lung disease and has been linked to lung cancer,and damage to human’s respiratory systems. Copper is an essential substance to human life, but in high doses it can cause anemia, liver and kidney damage, and stomach and intestinal irritation. Effect of the Mercury is to cause damage to the brain and the central nervous system. Chromium is used in metal alloys and pigments for paints, cement, paper, rubber, and other materials. Low-level exposure can irritate the skin and cause ulceration. Long-term exposure can cause kidney and liver damage, and damage too circulatory and nerve tissue. Chromium often accumulates in aquatic life, adding to the danger of eating fish that may have been exposed to high levels of chromium. Selenium causes to damage to circulatory tissue, and more severe damage to the nervous system.Mercury causes damages to the brain and the central nervous system,causes psychological changes and makes development changes in young children. Normally Mercury is a toxic substance which has no known function in human biochemistry. AN ALTERNATIVE TECHNIQUE TO REMOVE HEAVY METALS FROM WATERThe techniques of removing heavy metals from water are ordered as following,*chemical oxidation *ion exchange *reverse osmosis *electrochemical applications On the other hand, one of the alternative techniques to remove the heavy metals from the water sources is BIOSORPTION. Biosorption is a property of certain types of inactive, dead, microbial biomass to bind and concentrate heavy metals from even very dilute aqueous solutions. Microorganisms are used in biosorption. They take heavy metals into their cell surface or inside of bodies. That means microorganisms collect the heavy metals into inside. Sources of Biomass for Biosorption
Organisms for BiosorptionThere is a wide variety of microorganisms, including bacteria, fungi, yeast, and algae, that can interact with metals and radionuclides and transform them through several mechanisms Examples of toxic heavy metals accumulating microorganismsOrganism * Element Citrobacter sp. * Lead, Cadmium Thiobacillus ferrooxidans * Silver Bacillus cereus * Cadmium Bacillus subtilis * Chromium Pseudomonas aerugina * Uranium Micrococcus luteus * Strontium Rhisopus arrhizus * Mercury |
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Water pollution has many sources and characteristics. Humans and other organisms produce bodily wastes which enter rivers, lakes, oceans and other surface waters; Industry is creating new chemicals each year, all of which eventually find their way to water. In high concentrations these wastes result in bacterial contamination and excessive nutrient loading (eutrophication). Inorganic industrial wastes are much tricker to control and potentially more hazardous Industries discharge a variety of toxic compounds and heavy metals, and wastewater from industrial process may also be too hot or too low in dissolved oxygen to support life.
Heavy metals are dangerous because they tend to bioaccumulate. Bioaccumulation means an increase in the concentration of a chemical in a biological organism over time, compared to the chemical's concentration in the environment. Compounds accumulate in living things any time they are taken up and stored faster than they are broken down (metabolized) or excreted.