native freshwater microalgae play a crucial role in biofuel production due to their unique characteristics and environmental suitability. this study investigated the diversity of microalgae species in various freshwater ecosystems across northwestern ontario, canada and evaluated the nutrient removal, bioremediation and subsequent biomolecule production. microalgae are known for their biochemical diversity, synthesizing an extensive range of compounds including proteins, lipids, carbohydrates, vitamins, pigments, and bioactive molecules in chapter one, we provided a comprehensive review on the microalgae cultivation and harvesting techniques along with pretreatment methods for the extraction of biomolecules. in chapter two, we isolated 75 potential microalgal isolates and characterized these stains to identify those with high potential for lipid and biomolecule production capacity through a combination of microscopy, molecular techniques, and biochemical analysis and identified the optimal light condition for the biomass and lipid production. among these isolated strains, a five microalgae strains with higher lipid production and growth were identified using molecular and morphological approaches. among four different photoperiods, 16l:8d light/dark cycle produced significantly higher biomass and lipids for chlorella sorokiniana, chlorella vulgaris, and chlamydomonas sp. [...]