Development and operation of indigenous microalgal-bacterial consortium system treating eutrophic lake water:...

Natural water bodies such as the inland lake suffers from eutrophication due to excessive nutrient, particularly nitrogen and phosphorus. This study demonstrated an indigenous microalgal-bacterial consortium (IMBC) system to treat eutrophic lake. Three IMBC were enriched from eutrophic lake water or/and sediments, exhibiting superior growth and complete nutrient removals compared to two commercial microalgal species. Particularly, the IMBC3 enriched from lake water and sediment (volume ratio of 1:1) were found to simultaneously achieve 91.0 % settling efficiency, attributed to its larger flocs and surface physical properties (e.g., higher surface hydrophobicity (78.0 %), protein/polysaccharide ratio (10.7) and zeta potential (-19.1 mV)). Subsequently, a long-term photobioreactor using IMBC3 further demonstrated stable nutrient removal and cold tolerance year-around. The microbial community's shift towards cold-tolerant genera and alleviated photoinhibition likely enhanced nitrogen cycling efficiency during colder months. These findings offer a feasible alternative using the IMBC with good environmental adaptation to eutrophication mitigation in nature water.