Characterization of algal organic matter as precursors for carbonaceous and nitrogenous disinfection byproducts formation: Comparison with natural organic matter.

Algal organic matter (AOM) and natural organic matter (NOM) from a typical eutrophic lake were comprehensively investigated in terms of their physico-chemical property, components and disinfection byproduct formation potentials (DBPFPs). The relationships between specific chemical properties of AOM and NOM with their corresponding DBPFPs were further evaluated during chlorination. Results indicated that AOM had lower specific UV absorbance (SUVA) but richer organic nitrogen contents than NOM. Fluorescence excitation emission matrix spectroscopy further demonstrated that AOM were chiefly composed of aromatic protein-like and soluble microbial byproduct-like matters, while NOM were mainly contributed from humic acid-like and soluble microbial byproduct-like substances. Although the molecular weight (MW) distribution of AOM and NOM showed no significant difference, size-exclusion chromatography with organic carbon as well as organic nitrogen detection (LC-OCD-OND) revealed that AOM were concentrated with the fraction of building blocks and NOM had higher concentrations of biopolymers and humics (HS). Moreover, AOM displayed higher DBPFPs than NOM, especially for nitrogenous DBPFP (N-DBPFP). MW < 1 kDa fractions both in AOM and NOM contributed the largest proportion to the formation of carbonaceous disinfection byproducts (C-DBPs). In addition, Pearson correlation analysis showed that bulk parameter SUVA was significantly relevant to the formation potentials of trihalomethane both in AOM and NOM, but was ineffective for carbonaceous DBPFP (C-DBPFP) prediction. Dissolved organic nitrogen contents in biopolymer and HS characterized by LC-OCD-OND had strong correlations with N-DBPFPs from AOM and NOM, indicating that LC-OCD-OND quantitative analysis could improve the prediction accuracy of the DBP formation than bulk parameters during NOM and AOM chlorination.

[Transformation of Disinfection Byproduct Precursors During the Wastewater Regeneration Processes].

Disinfection byproduct(DBP) precursors during the wastewater regeneration processes were separated into hydrophilic fraction(HPI), hydrophobic fraction(HPO) and transphilic fraction(TPI) with macroporous resin. DBP precursors in these water samples were characterized with fluorescence excitation emission matrix, Fourier transformation infrared and nuclear magnetic resonance, and were further tested for their DBP formation potential(DBPFP) after chlorination. The results indicated that main DBP precursors in sewage were humic acid and aliphatic hydrocarbons, and were mainly dominated by HPI. Primary treatment(sedimentation) could effectively remove hydrophobic humic acid through the mutual exclusion between HPO and water. The removal of humic acid would lead to the obvious reduction of carbonaceous disinfection byproduct formation potential(C-DBPFP). In addition, nitrogenous disinfection byproduct formation potential(N-DBPFP) was found to be increased due to the increase of DON/DOC value. Although secondary treatment(biotreatment) was effective in removing humic acid and aliphatic hydrocarbons, it could produce a large amount of soluble microbial products(SMP), which led to the enhancement of HPO percentage. And the accumulation of SMP resulted in the significant increase of C-DBPFP and N-DBPFP. Humic acid and hydrophobic SMP could be removed by the advanced treatment(cloth filtration), leading to the reduction of HPO percentage and the increase of HPI percentage. The decrease of humic acid and hydrophobic SMP would cause the reduction of C-DBPFP and N-DBPFP in the advanced treatment.

Content determination of the flavonoids in the different parts and different species of Abelmoschus esculentus L. by reversed phase-high performance liquid chromatograph and colorimetric method.

BACKGROUND: This research will establish the ultraviolet colorimetric method to determine the total flavonoid content in different species and different parts of Abelmoschus esculentus L. MATERIALS AND METHODS: We establish the reversed-phase high-performance liquid chromatograph (RP-HPLC) method to determine the content of the three flavonoid glycosides in different species and different parts of the A. esculentus. Adopt the NaNO2-Al (NO3)3-NaOH colorimetric method to determine the total flavonoid content; at the same time, adopt the RP-HPLC method to determine the contents of the three flavonoid glycosides. Using the methods of ultraviolet colorimetry and RP-HPLC, we determined and analyzed the total flavonoid content and the content of the three flavonoid glycosides in different species and different parts of A. esculentus. RESULTS: There are great distribution differences of the total flavonoids and the three flavonoid glycosides in different species and parts of A. esculentus. Among them, the content of the effective constituents in the flower is relatively high, next is in the fruit. In the different species of A. esculentus, the content of the flavonoids of finger relatively high. The HPLC method established in this research is simple and convenient and its results are accurate and reliable. In addition, it has a very good repeatability. CONCLUSION: The results provided the reference data for the medicinal use of A. esculentus and it can be used in quality analyzing of its effective constituents.