POLLUTION OF ENVIRONMENT WITH HEAVY METALS, AND THEIR TOXICITY EFFECT

Abstract

Heavy metals are toxic materials and their compounds may cause harm to the environment as well humans. It has carcinogenic effects through its bioaccumulation over several years in plants and some specific organs of humans and animals such as liver, lungs, brain and kidneys, causing serious damage of these organs’ tissues ending with cancer and/or kidneys failure. Copper, zinc, cobalt and manganese are examples of heavy metals which are resulted from metabolism, but it can be toxic if their normal limit is exceeded.The key sources of environmental pollution due to heavy metals are the release of factory waste, laundry water and sewage flowing into rivers. This is in addition to the smoke released by factories, as well as combustion released from car exhausts and electrical generators into the air. Biological treatment using microorganisms such as bacteria (e.g. Actinomycetes), fungi (e.g. Aspergillus niger) and blue-green algae or cyanobacteria (e.g. Anabaena variabilis) are the most successful methods for the removal of heavy metals. The natural wastewater treatment systems are increasingly being used as alternative method for traditional treatment procedures due to their high efficiency, less maintenance costs and low running costs.