Study On The Release Of Nitrogenous Disinfection By-products Precursors Of Algal Water Under Environment Stress Conditions

In recent years China’s industry have made great progress, while the corresponding sewage management and treatment technology is very imperfect, eutrophication of water bodies is very serious and shows the trend of continued worsening. Nitrogen-containing organic compounds and nitrogenous disinfection by-products(N-DBPs) in drinking water is a hot topic at present in the fields of water treatment. In eutro PHic water algal grows vigorous and with the features of negative charge, hydro PHilic, steric effect and small proportion, therefore algal is very stable and difficult to remove in the water environment, bring a series of challenges for drinking water treatment and algal metabolites released by the cells during growth contain much organic nitrogen species, and they are considered as important N-DBPs precursors. While the algal under stress environment conditions, algal under great disturbance, the structure and properties of organic compounds are undergoing tremendous change, aggravating the difficulty of water treatment. this study mainly focus on the algal cells and algae organics matter(AOM), Analysing the trend of algal concentration and algae organic properties, and research the influence factors and formation mechanisms of N-DBPs in the chlorination process. establish the relationship between AOM and N-DBPs, provide data support for the release of metabolize organic matter under stress condition and follow-up experimental study of N-DBPs in the chlorination process.Select the most representative cyanobacteria of microcystis aeruginosa as the research object, Observe and analyze the Algal mor PHology, 3D fluorescence spectroscopy, DON, TOC and molecular weight distribution of AOM.The DON concentration of EOM Rise slowly at first and then sharply rising during the algal growth process. EOM in exponential PHase and decline PHase has similar molecular weight distribution, mainly in <1k Da and>100k Da areas. While EOM in stable mainly concentrated in the <30k Da area. Small changes the molecular weight distribution of IOM changes little during the growth period, mainly concentrated in <1k Da and >100k Da areas.Kinds of fluorescent substances in EOM changes little during the growth period, mainly humic substances and soluble microbial products; The fluorescent material of IOM was mainly aromatic proteins and soluble microbial products, DON accounted for the largest proportion of IOM in stable period.Through the analysis of EOM 3D fluorescence spectra, the stress effect on algae is mainly reflected on concentration but not species of organic matter in EOM. after environment stress, there is no new organic matter in EOM and the characteristic peaks of IOM in I and II fluorescence area(Ex<250nm, Em<380nm) did not appear too. This shows that algal concentration’s decrease mainly due to the abnormal metabolism of algal cells under stress conditions, algal eventually exhaust itself and decay to death. in microscope, algal itself of different posture, severe atro PHy, pale volume, while the broken and death due to the destruction of direct PHysical of the stress conditions is less. The mor PHology of N in EOM varied significantly under stress condition, compared with normal condition DON increased significantly, SUVA decreased, after stress effect Macromolecules hydro PHobic material was significantly reduced, small molecule hydro PHilic substances increased significantly, more likely leading to the formation of DBPs in the chlorination process.Compared with normal condition, EOM chlorinated N-DBPs generation has significantly differents. the production of N-DBPs increased significantly under High temperature, low temperature, hypoxia, UV irradiation, no significant change under strong agitation, and Substantially reduced under shading. The concentration of DON in EOM has different degrees of increase after environment stress, while N-DBPs generated of per unit mass EOM has significantly reduced except for hypoxia stress, shading stress minimum.UV254 of EOM decrease significantly after chlorination disinfection, The organic substances in EOM was almost destroyed, the characteristic peak of EEM also disappeared after chlorination, And there is some correlation between UV254 of EOM before disinfection and N-DBPs generation, but under weak relevant, R2 under natural and artificial stress conditions are 0.464,0.496 respectively.TCNM has the highest rate of generation during four kinds of typical N-DBPs monitored, TCNM accounted for 77.6 percent of total N-DBPs production under normal condition, 1,1,1-TCP、DCAN、TCAN 12.3%、8.8% respectively, TCAN minimum only 0.2%; TCNM is also the main N-DBPs under natural and artificial stress conditions.