Eutrophication, driven by excessive inputs of nutrients such as nitrogen and phosphorus, represents a significant global aquatic ecological challenge that requires immediate attention. Among the various remediation strategies available, microbial remediation has gained increasing interest due to its high efficiency, environmental friendliness, and sustainability. TThis study isolated three aerobic denitrifying and polyphosphate-accumulating strains (Y1: Pseudomonas orientalis; Y2: Serratia marcescens; Y3: Bacillus simplex) from the sediments of Caohai Lake in Guizhou Province, China, to enhance bioremediation efficacy in eutrophic waters. We systematically evaluated an immobilized composite microbial consortium, assessing its performance in nitrogen and phosphorus removal, as well as its stability in natural lake water. Orthogonal experiments identified an optimal composite ratio of Y1∶Y2∶Y3 = 3∶2∶1. Under conditions of sodium acetate as carbon source, a C/N ratio of 12, a temperature of 30°C, and a pH of 9, the removal rates of ammonium nitrogen (NH4+-N) and soluble reactive phosphorus (SRP) reached 73.2% and 90.6%, respectively. The immobilized microbial agent, formulated with 20 g/L sodium alginate (SA) and 30 g/L activated carbon (AC) as carriers, along with 10 g/L calcium chloride (CaCl2) as crosslinking agent, exhibited favorable stability and mass transfer performance. Scanning electron microscopy (SEM) observations confirmed the successful colonization of microorganisms within the carrier. After immobilization, the removal rates of SRP (99.3%) and NH4+-N (90.7%) increased by 22.1% and 13.2%, respectively, compared to free microbial communities. In conclusion, the synergistic effects between the composite microbial consortium and immobilization technology significantly enhanced the removal of nitrogen and phosphorus from aquatic systems, presenting a promising microbial remediation strategy for controlling eutrophication in karst lakes such as Caohai Lake.
Zhao et al. (Sun,) studied this question.