高密度蓝藻厌氧分解过程与污染物释放实验研究

摘要

采用批次培养实验模拟高密度蓝藻堆积发生的厌氧分解过程,分析蓝藻的分解速率及污染物释放规律.厌氧分解实验中,设置三组蓝藻初始密度分别为2.23×1012、1.19×l013、4.47×1013cells/L,得到叶绿素a的分解速率常数分别为0.074、0.133、0.081 d-1.蓝藻厌氧分解过程中水体呈酸性,电导率呈上升趋势,最高值为949μS/cm.化学需氧量持续升高,而UV254值先升高后降低,说明水体中有机物浓度增大,并逐渐由大分子分解为小分子有机物.蓝藻厌氧分解释放出大量溶解态氮、磷,溶解态有机氮逐渐被降解为无机氮,铵态氮含量占90％以上.研究表明,高密度蓝藻堆积发生厌氧分解可释放大量有机物和溶解态营养盐至水体中,并且随着蓝藻密度升高,污染物释放强度增大.因此水华期间应及时打捞蓝藻,以避免蓝藻大量堆积死亡导致水源区水质下降并影响自来水出水质量.%The anaerobic decomposition of high-density cyanobacteria and the kinetics of contaminants release were investigated based on a set of batch tests in this study. The results showed that the degradation rates of chlorophyll-a ( Chl. a were 0. 074, 0.133, and 0.081 d-1 , respectively, at different cyanobacterial densities of 2.23 × 1012 , 1.19 × 1013 and 4. 47 ×1013 cells/L, respectively. The chemical oxygen demand increased while the UV254 value increased initially and then decreased, suggesting that the release of organic compounds increased, but the molecules of which were reduced gradually during the degraded process. Accordingly , the pH of incubation solution remained acidic and the conductance increased, up to 949 μS/cm. The decomposition of cyanobacteria resulted in a high release of nitrogen and phosphorus. Moreover, dissolved organic nitrogen was degraded gradually into inorganic nitrogen form, in which the amount of ammonia nitrogen accounts for 90% . The results demonstrate that the anaerobic decomposition of high-density cyanobacteria can release a large amount of organic compounds and nutrients into water, furthermore the release of contaminants increases with the increasing density of cyanobacteria. Therefore, to avoid high-density cyanobacteria deteriorating water quality and even threatening drinking water safety, we need to remove cyanobacteria timely when algal bloom occurs in the lake which is served as water resource.