Experimental studies on effect of Heavy Metals presence in Industrial Wastewater on Biological Treatment

Biological Wastewater Treatment is one of the most important parts of wastewater treatment and microorganism has importance role in biological treatment. Microorganisms effect in metabolism of various organic compounds and other elements. Such microbiological parameters as the number, weight and activity of microorganisms can be good indicators of wastewater contamination with heavy metals. Heavy metals are known as harmful pollutants in Wastewater having a negative effect on Biological Wastewater Treatment plant including microorganisms. Some heavy metals, e.g. lead, even at low levels are toxic for microorganisms. As a rule, heavy metal has a negative effect on the growth of water microorganisms as it can greatly depress their numbers. On one hand, the number of microorganisms depends on the total content and concentrations of particular forms of heavy metals. On the other hand, it is conditioned by several other factors, quantity and quality of organic matter, especially carbohydrate rich organic matter, pH, total exchange capacity, nutrient availability, moisture, temperature and oxygen availability. Heavy metals shift the structure of microbial populations, impoverish their diversity, and affect species composition, reproduction and activity of indigenous microorganisms. Contamination of wastewater with high rates of heavy metals caused a significant decrease in the numbers of bacteria in biological system. It is obvious that heavy metals are very danger contaminant in wastewater and disorder of biological wastewater treatment is as a result of this pollution.