Phycoremediation: An eco-friendly algal technology for bioremediation and bioenergy production

Substantial amount of the refractory organics; inorganic nutrients, mainly nitrogen and phosphorus; heavy metals; etc. is discharged in conventional wastewater treatments. The concentration of such contaminants in the discharged wastewater depends on the performance and maintenance of the wastewater treatment plants (WWTPs). Though further reduction in such contaminants is possible with an aid of some of the advance technologies and skilled manpower, it makes wastewater treatment more expensive. More importantly, the running and maintenance of WWTPs are uncommon in economically weaker countries especially in the rural areas. This leads to the hunt of economically viable and environmentally sustainable alternative wastewater treatments. The truism nowadays is to recognize the emergence of phycoremediation as an alternative. Algae-based bioremediation has been found excellent for the nutrient, organic, pathogen, heavy metal, etc. removal from various types of wastewater. Green microalgae possess the unique potential of high photosynthetic activity compared to food crops and terrestrial plants. Therefore, such systems are capable of high biomassproduction through CO₂ sequestration from the air and nutrient and organic sequestration from water. The microalgal cells contain comparatively high lipid contents; thus, algal biomass serves as an excellent feedstock for biofuels. Therefore, the choice of algal species possessing excellent phytoremediation potential as well as capable of producing high biomass is important to consider while designing the phycoremediation-based treatment systems. In this chapter, a concise partial overview of the potential and uniqueness of phycoremediation in treating various types of water and production of algal biomass for biofuels has been discussed. The environmental sustainability and economic viability aspects of phycoremediation, factors influencing the wastewater treatment, and the limitations of such technologies are covered briefly.