URBAN WASTEWATER TREATMENT BY FRESHWATER MICROALGAE CHLORELLA VULGARIS

Wastewater is produced by human activities in urban, agricultural, and industrial sectors.Nowadays, collecting wastes and removing pollutants from various wastewaters is emphasized as they can potentially contaminate food and water resources. Wastewaters are also considered a very favorable environment for the growth of various types of pathogenic microorganisms. Relatively large volumes of organic and inorganic (mineral) substances are unfortunately released to wastewaters by various industries, having detrimental effects on human health if they enter the food cycle of humans or animals. Accordingly, it seems essential to manage and remove pollutants from wastewaters. Despite improved conventional water treatment technologies, most wastewater treatment plants face a major challenge regarding required standards for removing nitrogenated and phosphate nutrients to discharge and reuse treated wastewater. High energy consumption, prolonged operation, carbon emissions, and large sludge volumes are other obstacles. Most countries have enacted strict laws for treating urban wastewater, either for reusing or discharging treated wastewater to water resources and the environment. Recently, there has been a great interest in microalgae to replace conventional wastewater treatment methods or use in combination with activated sludge due to their high potential for removing pollutants and reducing nutrients up to low concentrations. Microalgae prevent eutrophication by removing nitrogen and phosphorous [۱, ۲]. For the first time, Ostwald found the role of microalgae in treating wastewaters, and microalgae were first cultured in wastewater in the ۱۹۷۰s to remove nutrients [۳, ۴]. Microalgae have been extensively used in wastewater treatment in the past five decades, highlighting their role as much as conventional wastewater treatment processes. This study investigates the role of Iranian local microalgae Chorella vulgaris in removing nutrients from raw urban wastewater (amine and phosphorous compounds), the growth of microalgae in the presence of naturally found bacteria in wastewater and produced biomass weight. Raw urban wastewater samples were obtained from the West Town wastewater treatment plant after initial sedimentation. Batch tests in a shaking incubator were performed to evaluate the removal of nutrients and microalgae growth in wastewater. Coliform bacteria remaining in the culture medium were also examined.