Bioremediation of Heavy Metals through Fresh Water Microalgae: A Review

Industrial development has created a serious problem by emitting waste water containing many different kinds of pollutants including heavy metals. There are several chemical and physical processes for heavy metals removal but bioremediation technology has also good prospect. As the waste water from different industries is deposited in the rivers nearby so aquatic flora are needed to be studied more to be used to remove all these heavy metals. Freshwater microalgae are one of the potential organisms which can be safely used without any hazard to the environment. Instead of that the algal flora will help to reduce the carbon component in the waste water, as well as to remove the nitrate and phosphate component, whereas the oxygen cotent will increase in the water. There are various reports about the heavy metal uptake capacity of microalgae by different means, by adsorption or by intercellular uptake which are ultimately detoxified by metallothioneins or phytochelatins or are sequestered into the vacuoles or polyphosphate bodies. There are various Marine Algal flora which can really remove various heavy metals from aquatic environment, but we are more concerned about the heavy pollutants in rivers and waste water bodies where the fresh water microalgae can be used successfully. High Rate Algal Ponds or Algal Turf Systems are being used successfully for removal of pollutants in some places. But more studies should be done for using other combined technologies like immobilized algal cultures along with other to improve the different pollutants removal capacity by freshwater microalgae. Transgenic algae production must be attempted to increase their potentiality in these aspects by manipulating the detoxifying mechanisms. In this review article a brief account has been presented about the present status in this area of research and some suggestions what may be attempted in future to implement this technique to make our environment pollution free.