Bioremediation of Wastewater Using a Novel Method of Microalgae Immobilized on Twin-Layer Recirculation System (TLRS)

Abstract

Effluent is a general term used to represent the water with poor quality that contains more amounts of pollutants and microbes. The effluent is discharged into the nearby water bodies; it can cause serious environmental and health problems to human beings. Bioremediation is an ecofriendly technique to reduce the pollutant and other contaminants present in effluents. Effluent treatment involves several processes which can be classified as physical, chemical and biological based on the method adopted for treatment. Physical treatment includes sedimentation (clarification), screening, aeration, filtration, skimming, flotation and degasification. These treatment methods consume more energy and it involves higher costs. Chemical treatment includes chlorination, ozonation, neutralization, coagulation, adsorption and ion exchange. These methods could be expensive as well as harmful to the environment. Biological treatment is the best option for treating high-strength wastewater, because it is cost-effective, efficient and successful cleaning technique for treatment of effluents. The successful operation of biological waste treatment processes depends on the use of bacteria, algae, fungi, protozoa, etc. Microalgae are one of the best bioremediators for the treatment of effluent. Algal group are playing a very important role in bioremediation process. It has the capacity to produce oxygen during photosynthesis and it also provides the basis for maintenance of good water quality by means of self-purification, especially in those deeper surface waters that are still clean and healthy. During their growth, they trap sunlight and CO₂ from the environment for their photosynthesis. Bioremediation using microalgae has a number of positive applications over the conventional methods as it is cost-effective and useful in treatment of wastewater, in CO₂ sequestration, in sanitation and also in the production of renewable sources of energy such as biodiesel, biofuel, glycerol, methane gas, hydrogen gas, biofertilizers, etc.