Chlorella vulgaris has been used in the biological treatment of some pollutants and heavy metals in municipal wastewater

Abstract

This study aims to prove the ability of Chlorella vulgaris to treat some pollutants such as nitrates, nitrites, phosphates, ammonia, the chemical oxygen requirement and some heavy metals such as cadmium and copper present in the water of municipal wastewater treatment plants. Water samples were taken from Al-Rumaitha Central Water Treatment Plant, Al-Muthanna Governorate, Iraq. Contaminated water was added to the algal culture after the algae reached the Stationary phase after 10 days of growth. The tests were performed on the water after two periods, the first after 4 days of the algae reaching the Stationary phase and the second after 8 days before the arrival of the algae to the Death phase. The results showed a high efficiency of Chlorella vulgaris in treating polluted water. The removal percentage after 4 days of exposure period was as follows: BOD5 86.6%, nitrate 62.9%, nitrite 14.7%, ammonia 94.2%, and phosphate 86.2%. As for the heavy elements, they were as follows: copper 98.9%, cadmium 94.75%. After 8 days of the treatment process, the efficiency of the algae was better than the previous days, where the results showed the following removal percentages, BOD5 88.4%, nitrate 63.7%, nitrite 23%, ammonia 97.9%, phosphate 87.3%. As for heavy metals, the percentages were as follows: copper 99.2%, cadmium 97.9%. The results of this study showed the efficiency of Chlorella vulgaris in the treatment process and its high ability to remove pollutants from water, especially nutrients and heavy metals, and green algae is a promising, highly efficient and environmentally friendly biological treatment technology. Keywords: heavy metals, Chlorella vulgaris, wastewater