Potential of Local Algae Strains for Possible Hydrogen Production and Phytoremediation of Wastewater /

Abstract

Due to rapid urbanization, population explosion and widespread industrialization, the twin problems of energy security and global warming are gaining momentum as dependency on fossil fuels continues. Increased greenhouse gas emissions along with release of untreated wastewater from different sectors pose a serious threat to sustainable environment. As the global search for solutions to these problems continues, wastewater treatment by microalgae is an attractive option which achieves two goals simultaneously: Phyto-remediation and biomass as a feedstock for biofuel production. Furthermore, many algal species have the ability to generate hydrogen gas in anaerobic mode due to the presence of hydrogenase enzyme. This process is an electron dependent reaction which commences upon the photolytic splitting of water molecules which releases electrons and protons in photosystems of algal chloroplasts. In the absence of oxygen, these electrons are transported to hydrogenase that reduces protons and generates renewable fuel hydrogen gas. Using this background knowledge, this study is designed to explore the hydrogen production and wastewater phytoremediation ability of local algae strains. The local algal strains were first isolated and preserved, then cultivated aerobically under ambient conditions in synthetic growth medium (BBM) till exponential growth phase. Afterwards, these strains were exposed to anaerobic conditions for the maximum transfer of electrons towards hydrogenase to determine hydrogen potential. Afterwards, as another research objective, local algae strains were subjected to cultivation in institutional and textile wastewater samples acquired to determine their phtyoremediation ability along with hydrogen gas potential. Results showed all strains having hydrogen generation ability and good removal efficiency of major nutrients (phosphates, sulfates, nitrates), BOD and COD from wastewater, thereby improving overall water quality. In addition, algal biomass was harvested and used for lipid extraction and determining other biofuel potential via FTIR analysis. Hence this study reflects an environmentally safe alternative for treating wastewater which is not only cost effective, but also yields far better results in reducing water pollution and providing potential sources of biofuel.