再生水中小球藻分解对水质特性及微生物群落的影响OA

This study investigated the environmental impact of algal decomposition in reclaimed water used for landscaping by simulating the release and decay of Chlorella vulgaris(at 3 g·L−1)over 22 days.Typical water quality parameters were monitored alongside high-throughput sequencing to analyze the release and decomposition patterns of carbon,nitrogen,and phosphorus,as well as the dynamics of the microbial community.The results showed that the decay coefficient of algae dry mass was(0.036±0.004)d−1.The mass concentrations of total nitrogen(TN)and ammonium nitrogen(NH3-N)in the water increased,with a mean daily increase rate of TN was 1.29±0.17 mg·(L·d)−1 over the 22-day period.Total phosphorus(TP)and orthophosphate(PO43−-P)levels remained stable for the first 13 days,after which TP increased at a mean daily rate of 0.45±0.04 mg·(L·d)−1.The average daily increase in chemical oxygen demand(COD)was(11.95±1.58)mg·(L·d)−1 in the first 13 days,ffollowed by a decrease of 1.46±0.50 mg·(L·d)−1 from day 13 to 22.Among them,the content of macromolecular organic matter(with a molecular weight greater than 100 kDa)decreased from 17.45%on the 13th day to 2.41%on the 22nd day.The content of organic matter with a molecular weight of 10～30 kDa increased from 1.42%to 25.54%,indicating that the macromolecular organic matter released by the decomposition of algae was degraded into medium-molecular organic matter in the later stage.In the microbial samples of the algae residue,the abundances of phyla such as Proteobacteria,Bacteroidota,and Firmicutes,as well as genera such as Monoglobus,Hirschia,and Steroidobacter,which are involved in the degradation of organic substances like polysaccharides,were higher on day 13 than those on day 0.FAPROTAX analysis further confirmed increased abundances of microorganisms involved in fermentation and dark hydrogen oxidation by day 13.These findings indicate that the degradation of organic matter from algal sources promoted the enrichment of some denitrifying bacteria and optimized the microbial community structure.