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Surrogate measurements based on excitation-emission matrix fluorescence spectra (EEMs) and ultraviolet-visible absorption spectra (UV-vis) were used to monitor the evolution of dissolved organic matter (DOM) in landfill leachate during a combination of biological and physical-chemical treatment consisting of partial nitritation-anammox (PN-Anammox) or nitrification-denitrification (N-DN) combined with granular active carbon adsorption (GAC). PN-Anammox resulted in higher nitrogen removal (81%), whereas N-DN required addition of an external carbon source to increase nitrogen removal from 24% to 56%. Four DOM components (C1 to C4) were identified by excitation-emission matrix-parallel factor analysis (EEM-PARAFAC). N-DN showed a greater ability to remove humic-like components (C1 and C3), while the protein-like component (C4) was better removed by PN-Anammox. Both biological treatment processes showed limited removal of the medium molecular humic-like component (C2). In addition, the synergistic effect of biological treatments and adsorption was studied. The combination of PN-Anammox and GAC adsorption could remove C4 completely and also showed a good removal efficiency for C1 and C2. The Thomas model of adsorption revealed that GAC had the maximum adsorption capacity for PN-Anammox treated leachate. This study demonstrated better removal of nitrogen and fluorescence DOM by a combination of PN-Anammox and GAC adsorption, and provides practical and technical support for improved landfill leachate treatment.

Anammox-based processes have been intensively studied for the nitrogen removal from leachate, but less attention was paid to monitoring the evolution of leachate organics. In this study, fluorescence Excitation-Emission Matrix (EEM) measurement coupling with Parallel Factor Analysis (PARAFAC) analysis was used to supplement the routine monitoring in order to reveal more insights into pollutants removal during the leachate treatment by a one-stage partial nitrification-Anammox process (PNA). During this PNA process, up to 96% of total nitrogen and 43% of COD were removed, indicating the potential of PNA process to simultaneously remove nitrogen and organics. Fluorescence intensities and ratios clearly showed the dynamics of influent fluorophores during seasonal variations, where a high amount of protein-like compound was observed during summer months. Protein-like compound was preferentially removed (43–63%) in the PNA process, whereas humic/fulvic-like compounds exhibited recalcitrance to biodegradation. The increase of oxygen supply promoted protein-like compound degradation, which could be associated with the aerobic oxidation pathway. Furthermore, the protein-like compound removal was linearly correlated with the reduction of NH4+-N at limited oxygen conditions (i.e., air flow rate ≤1.6 Lgas/h/Lreactor) (r = 0.97, n = 65). The fluorescence directly extracted at Ex/Em:230 nm/345 nm was strongly correlated with the biodegradable chemical oxidation demand (BCOD) (r = 0.92, n = 204), showing its high potential as an indicator for biodegradable organics. Given the relatively weak correlation between fluorescence parameters and COD, EEM coupled with multivariate partial least squares (PLS) modeling was proposed and exhibited good predictive power for COD, as exemplified by a mean error of 4.5%.

Acrylonitrile (C3H3N) widely used in chemical raw materials has biological toxicity with –CN bond, so it is the key to removal of cyanide from acrylonitrile wastewater. In our previous research and investigation, a strain was identified as Arthrobacter nitroguajacolicus named ZJUTB06-99 and was proved to be capable of degrading acrylonitrile. In this paper, the strain ZJUTB06-99 was domesticated with acrylonitrile-containing medium and its decyanidation and denitrification in simulated acrylonitrile wastewater were studied. The intermediate product of acrylonitrile in degradation process was identified through gas chromatography–mass spectrometer, as well as the biodegradation pathway of acrylonitrile in wastewater was deduced tentatively. The kinetics equation of biodegradation of acrylonitrile was lnC = − 0.1784t + 5.3349, with the degradation half-life of acrylonitrile in wastewater by 3.885 h. The results of this study showed that the optimum levels of temperature, pH and bacteria concentration to attain the maximum biodegradation were obtained as 30 °C, 6 and 100 g/L, respectively. The disadvantages of the biodegradation with this strain and its possible enhanced method to degrade acrylonitrile in wastewater were also discussed.