Purifying Heavily Polluted River Water Using Immobilized Native Photosynthetic Bacteria

Black putrid river water is often found in densely populated regions with rapid economic development and population growth. This study proposes immobilized native photosynthetic bacteria (PSB), a group of bacteria that can survive in and simultaneously purify a wide range of polluted water bodies, as a novel method for treating heavily polluted river water. A native photosynthetic bacterial (PSB) colony that is a mixture of Rhodovulum strictum and Thiococcus pfennigii was isolated from river sediment (River Zaoyu, Beijing), enriched, and immobilized to purify heavily polluted river water. Consequently, the immobilized PSB was used to treat heavily polluted river water (from the River Zaoyu), with results showing a 70.5% reduction in chemical oxygen demand (COD) in 120 h. The removal efficiency of sulfide and ammonia nitrogen reached 91.7% and 28.3% in 48 and 24 h, respectively. In addition, the dissolved oxygen concentration rose from 0.31 to 1.52 mg L−1 in 48 h. Moreover, the heavily polluted river water became much less turbid following immobilized PSB treatment. This study demonstrates that the applicability of PSB in purifying heavily polluted river and immobilizing microorganisms like the PSB could be a prospective approach to enhance their performance in water bodies with low carbon, low dissolved oxygen (DO), high nitrogen, and high phosphorus.