Characterization of landfill leachate by spectral-based surrogate measurements during a combination of different biological processes and activated carbon adsorption.

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.

Sustainable hydrochar as an efficient persulfate activator for cost-effective degradation of bisphenol A.

This study explored Mason pine-derived hydrochar (MPHC) as an effective adsorbent and persulfate (PS) activator for degrading bisphenol A (BPA). Increasing MPHC dosage from 0.25 to 2.0 g L-1 raised BPA removal from 42% to 87%. Similarly, at the same MPHC dosage range and fixed PS concentration (8 mM), BPA removal by MPHC/PS increased from 66% to 91%. Additionally, at a fixed MPHC dosage (1.0 g L-1), higher PS concentrations (2-32 mM) resulted in an overall BPA removal increase from 78% to 99%. The optimal pH for BPA removal by MPHC was at pH 3, while for MPHC/PS was at pH 9. BPA degradation by MPHC was optimal at pH 3, whereas MPHC/PS was at pH 3 and pH 9. Additionally, pH 7 favored BPA adsorption for both MPHC and MPHC/PS. The study also considered the influence of coexisting anions and humic acid (HA). PO43- and NO3- influence adsorption on MPHC, but these anions' effect on MPHC/PS is limited. Furthermore, the existence of HA had minimal influence on BPA removal by MPHC/PS. The contributions of different reactive species by MPHC for BPA degradation are as follows: electron-hole (h+) 2%, singlet oxygen (1O2) 7%, superoxide radicals (O2•-) 13%, electron (e-) 2%, hydroxyl radical (•OH) 3%, whereas the remaining 48% removal was the contribution of adsorption. For MPHC/PS, adsorption accounted for 39 %, more reactive species were involved in degradation, and the donations are (h+) 3%, sulfate radicals (SO4•-) 3%, (1O2) 19%, (O2•-) 15%, (e-) 2%, and (•OH) 2%. Additionally, the performance of MPHC remains stable after three operational cycles. The preparation cost of MPHC is 3.01 € kg-1. These results highlight the potential of MPHC as an environmentally friendly material for activating PS and removing organic pollutants, suggesting its promising application in future environmental remediation efforts.

Combining ozone with UV and H2O2 for the degradation of micropollutants from different origins: lab-scale analysis and optimization.

The degradation of micropollutants (MPs), including pesticides, herbicides, pharmaceuticals and endocrine disrupting compounds, by ozone-based advanced oxidation techniques (AOP) was investigated in this study. The effect of different factors, such as ozone concentration, hydrogen peroxide concentration and initial pH, on the removal rate was studied in detail. The combination of UV with ozone/ H2O2 increased the MPs degradation. For example, atrazine removal increased from 12.6% to 66.9%. Increasing the concentration of ozone and H2O2 can enhance the degradation efficiency of MPs, while excess H2O2 plays a role as a scavenger for •OH. In addition, the optimizing conditions of degradation of MPs by an ozone-based AOP were investigated in this study. The optimal dosages of ozone for atrazine (ATZ), alachlor (ALA), carbamazepine (CBZ), 17-α-ethinylestradiol (EE2) and pentachlorophenol (PCP), were in the range of 0.6-0.75, while for ATZ a much higher dosage (5.4 mg/l) is needed. The optimal dosages of H2O2 concentration were at 0.75, 0.2, 0.47, 0.75 and 0.63 mM, and pH were at 10, 10, 7, 10 and 10, and reaction time at 38.5, 33.5 43, 6 and 6 min, respectively. Ozone-based AOP and in particular combination of UV with ozone and H2O2 is efficient to degrade atrazine, alachlor, carbamazepine, 17-α-ethinylestradiol and pentachlorophenol, and is attractive for future application of real wastewater treatment.