Athanasia G. Tekerlekopoulou

Wine lees are a phenolic-rich winery by-product whose liquid fraction remains underexploited. This study investigated the direct recovery of phenolic compounds from the liquid fraction of red wine lees (LfWL) using the non-ionic Amberlite XAD-16 resin through batch and fixed-bed adsorption, followed by sequential desorption and LC-HRMS profiling. Batch adsorption experiments were conducted at resin dosages ranging from 20 to 120 g/L. The highest adsorption yield (89.9%) was achieved at 120 g/L, whereas the highest experimental adsorption capacity (123.5 mg SAE/g) was obtained at 20 g/L. Adsorption kinetics were better described by the pseudo-second-order model, whereas the non-linear Langmuir model provided the best equilibrium fit, with a model-estimated maximum adsorption capacity of 304.34 mg SAE/g. Phenolics adsorption was favored at the natural pH of the LfWL, while the thermodynamic analysis indicated an exothermic and thermodynamically favorable process. Two different fixed-bed columns were evaluated under continuous flow conditions. The configuration with larger dimensions (LFB-200) treated an undiluted LfWL, reaching an adsorption efficiency of 36.59% with a breakthrough profile extending beyond 1400 min. Sequential elution with water followed by a 50% (v/v) ethanol/water mixture resulted in desorption yields of 88.96% and 79.54% for the small and large columns, respectively. LC-HRMS enabled the putative annotation of 20 phenolic compounds and revealed compound and class-dependent elution profiles. These results support resin adsorption as a promising route for direct phenolic recovery from liquid wine lees fractions.

The development of sustainable electrode materials for electrochemical nitrate removal from water has attracted increasing interest due to the need for efficient and environmentally friendly nitrate removal technologies. This paper presents the development and electrochemical evaluation of electrodes for nitrate-associated electrocatalytic activity using sustainable materials. Algal biomass and mineral hematite, which are abundant and low-cost resources, were employed alongside hydrothermal treatment and pyrolysis, resulting in the formation of an iron-enriched hybrid aerogel with distinct structural configurations. The physicochemical properties of the prepared materials were investigated by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and electrical conductivity measurements. Their electrochemical performance was evaluated by cyclic voltammetry in sodium sulfate electrolyte containing different nitrate concentrations (0–25 mM NO₃⁻). Electrochemical measurements demonstrated that the combination of biochar with hematene nanosheets is a promising approach for developing fully sustainable electrodes with the potential for electrochemical nitrate treatment in polluted water. Linear sweep voltammetry and scan-rate-dependent cyclic voltammetry measurements further revealed significant differences in background current and hydrogen-evolution behavior among the electrodes. These findings demonstrate that iron-doped algal biochar aerogels are promising sustainable electrodes for electrochemical nitrate treatment and support the development of low-cost, environmentally friendly water denitrification technologies.

Natural zeolite was investigated for ammonium nitrogen (NH₄⁺–N) removal from both synthetic aqueous solutions and real pretreated landfill leachate using batch and continuous-flow systems. Batch experiments were conducted at initial NH₄⁺–N concentrations ranging between 5 and 35 mg/L and zeolite dosages ranging between 10 and 50 g/L. Additionally, real pretreated landfill leachate (35 mg/L NH₄⁺–N) was treated using zeolite dosages of 10–75 g/L, achieving removal efficiencies up to 94%. Equilibrium and kinetic data were analyzed using Langmuir and Freundlich isotherms and pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. The Freundlich isotherm and PSO model best described the experimental data, indicating heterogeneous, multilayer adsorption governed primarily by chemisorption mechanisms. Continuous fixed-bed column experiments were performed under various flow rates, initial NH₄⁺–N concentrations, and zeolite masses. The resulting breakthrough curves were modeled using the Clark and modified Clark models, with the modified form showing improved predictive performance. The experimental data were further utilized to develop a MATLAB-based global fitting algorithm incorporating shared parameters across operating conditions. The model demonstrated strong predictive capability for fixed-bed breakthrough behavior. Overall, the results highlight the effectiveness of natural zeolite applicability as a low-cost and efficient post-treatment adsorbent for ammonium removal from complex wastewater streams.

BACKGROUND: Tris(2‐chloropropyl) phosphate (TCPP), a representative chlorinated organophosphate ester (OPE), has attracted increasing concern because of its persistence and toxicity in aquatic environments. Although the electro‐Fenton (EF) process is promising for refractory pollutant removal, its performance is often limited by cathode activity. In this study, blue‐green algae‐derived carbon quantum dots (BGA‐CQDs) were introduced as sustainable modifiers for a gas diffusion electrode (GDE) cathode to enhance TCPP degradation. RESULTS: Compared with the pristine GDE, the BGA‐CQDs‐modified GDE (CQDs‐GDE) exhibited improved electrochemical activity and pollutant removal performance. Under the optimal conditions of CQDs:CB = 1:2, 50 mM Na ₂ SO ₄ , pH 3, and an aeration rate of 200 mL min ⁻¹ , the EF system achieved 91.17% and 88.78% of COD and TOC removal within 180 min, respectively. In addition, the pseudo‐first‐order rate constant reached 0.0131 min ⁻¹ , while the electrical energy consumption was 10.55 kWh kgCOD ⁻¹ . Moreover, the modified GDE maintained over 70% COD removal even after six consecutive cycles, whereas the pristine GDE decreased to 36.75%. The combined LC–MS analysis and DFT calculations indicated that TCPP degradation mainly proceeded through hydroxylation, dechlorination, and ester bond cleavage, to yield less toxic intermediates. CONCLUSION: BGA‐CQDs effectively enhanced the catalytic activity and stability of the GDE cathode in the EF process. This study demonstrates a sustainable strategy for converting algal biomass into functional electrode materials for efficient degradation of organophosphate pollutants. © 2026 Society of Chemical Industry (SCI).

Propyl-paraben (PrP) is a common preservative found in cosmetics and pharmaceutical products. It is classified as a category 1 endocrine-disrupting compound, which highlights the importance of efficiently removing it from water during treatment processes. This study investigates the potential of using Leptolyngbya sp. dominated cyanobacterial biomass residues, in both their raw and hydrothermally treated (hydrochar) forms, for the removal of PrP from aqueous media. Batch and fixed-bed column experiments were carried out under varying conditions to assess adsorption kinetics and equilibrium behavior. Both raw biomass and hydrochar exhibited satisfactory PrP removal, achieving maximum adsorption capacities of 224.58 and 258.55 mg/g respectively, at 10 mg/L initial PrP concentration and 23.33 mg/L adsorbent dosage. Equilibrium data were best described by the Freundlich isotherm model, indicating a heterogeneous surface and multilayer adsorption. The kinetic analysis revealed that the adsorption behavior, for both adsorbents, was best described by the pseudo-second-order model, while the thermodynamic evaluation revealed negative ΔH° and ΔS° values, confirming an exothermic, physisorption-driven process. The adsorption mechanism was further investigated through surface characterization techniques, including Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, N₂ physisorption, and zeta potential analysis. The findings demonstrate the potential of microalgal biomass as a low-cost, sustainable biosorbent, for emerging contaminants, reinforcing its role in advanced water treatment and circular economy strategies.

This study investigates the implementation of an attached-growth pilot-scale biofilter for the biological treatment of mixed dairy wastewater derived from real industrial effluents, consisting of equal proportions of raw second cheese whey (SCW) and pudding dessert wastewater (PDW). The biofilter was inoculated with indigenous microorganisms derived from the mixed wastewater stream with initial dissolved Chemical Oxygen Demand (d-COD) concentrations ranged from 1000 to 12,500 mg/L. The removal performance of organic and inorganic components was evaluated at a recirculation rate of 1.0 L/min, resulting in d-COD reductions of up to 92.3% and removal rates reaching 194.6 mg/(L·h). High removal rates were recorded for ammonium (up to 99.9%) and TKN (92.2–98.7%), while nitrate removal varied (29.4–89.3%) and solids removal exceeded 92%. d-COD concentrations of treated effluent consistently met discharge or municipal disposal legislation values, demonstrating the system’s efficiency and stability and proposing it as an ideal solution for wastewater treatment in dairy facilities.

BACKGROUND: Printing ink wastewater (PIW) contains high concentrations of organic matter, suspended solids, and colorants that challenge conventional treatment methods. Electrocoagulation–electroflotation (EC/EF) has emerged as a promising technique for such complex effluents. This study aimed to evaluate the efficiency of EC/EF using aluminum, iron, and stainless‐steel electrodes for PIW treatment and to assess performance improvements when coupled in a single step with adsorbents, such as palygorskite (EC/EF–P) and zeolite (EC/EF–Z). RESULTS: Initial optimization focused on pH (5.0, 6.0, 7.5) and electrode type. Varying initial COD concentrations (~10 000–27 000 mg/L) had negligible impact on removal efficiencies, which remained high: COD (>90%), total suspended solids (>99%) and color (>90%). Notably, at lower initial COD levels (12 000 and 9970 mg/L), effluent COD concentrations were reduced below 1000 mg/L, meeting the discharge limits of the regional centralized wastewater treatment plant. The EC/EF–P and EC/EF–Z systems revealed that adsorbent addition significantly enhanced process performance. Palygorskite (6.0 g/L) accelerated COD removal, particularly under suboptimal electrochemical conditions, indicating its synergy with the EC/EF process. Zeolite (6.0 g/L) at pH 6.0 increased COD removal rate to 73.28 mg/(L·h) (20 min), compared to 48.38 mg/(L·h) (30 min) with palygorskite. CONCLUSION: These findings highlight EC/EF, especially when augmented with adsorbents, as a highly effective strategy for rapid and compliant treatment of high‐strength industrial wastewater. © 2026 Society of Chemical Industry (SCI).

BACKGROUND: Dairy wastewater (DWW) is characterized by high organic and suspended solid loads and its treatment remains a challenge for sustainable dairy industry operation. This study evaluates electrocoagulation‐electroflotation (EC/EF) with aluminum electrodes for treating real DWW under both batch and continuous‐flow conditions. RESULTS: Experiments were performed in situ at the industry using fresh wastewater with variable initial pH (5.0–7.0), chemical oxygen demand (COD ₀ :10800–3200 mg/L), and total suspended solids (TSS: 880–2030 mg/L). Batch experiments at current intensities of 0.15, 0.25, 0.5, and 1.0 A showed that 0.25 A (89.2 A/m ² ) was particularly effective, achieving 79.75% COD and 95.76% TSS removal within 10 min at 10800 mg/L COD ₀ and natural pH 5.33, with low energy consumption (0.14 kWh/m ³ ) and aluminum dissolution (27.96 g/m ³ ). For adjusted initial pH values of 5, 6, and 7 and COD ₀ = 3200 mg/L, maximum COD and TSS removal occurred at pH 5, likely due to its proximity to the isoelectric point (~pH 3.7). Similarly, for COD ₀ = 6200 mg/L, treatment at natural pH 6 yielded 79.22% COD and 90.37% TSS removal. At 4500 mg/L COD ₀ , maintaining natural pH 6.7 reduced treatment time from 30 to 20 min while sustaining COD removal (~63%), although TSS removal dropped by ~36%. Continuous‐flow experiments at COD ₀ = 6500 mg/L achieved steady‐state removal of ~72% COD of and 98% TSS at pH 5 with a 15‐min hydraulic retention time. CONCLUSION: Overall, EC/EF proved technically viable, energy‐efficient, and effective for high‐strength DWW treatment, supporting its use as a pretreatment step in decentralized or industrial wastewater treatment systems. © 2026 Society of Chemical Industry (SCI).

Many individual wastewater streams exhibit imbalanced or poor nutrient profiles, limiting their suitability for efficient biological treatment. In regions where several agro-industrial activities coexist, these streams are often produced in small volumes and vary considerably in composition, making their combined use an effective way to obtain a more balanced influent. This study aimed to identify the optimal mixing ratio of two agro-industrial wastewaters, second cheese whey (SCW) and poultry wastewater (PW), for the cultivation of a Leptolyngbya-dominated consortium. Four mixing ratios of SCW:PW (50:50%, 60:40%, 70:30%, and 85:15%) were examined based on an initial dissolved chemical oxygen demand (d-COD) concentration of 3000 mg L⁻¹. The 70:30% ratio was led to significant biomass production (268.3 mg L⁻¹ d⁻¹), while simultaneously exhibiting the highest lipid content (14.0% d.w.), and the highest removal of d-COD (89.2%), total nitrogen (64%) and PO₄³⁻-P (60%). Overall, the experiments showed that using nutritionally balanced wastewater streams is a promising strategy to enhance biological treatment efficiency and lipid production.

Surplus cyanobacterial biomass can serve as a low-cost sorbent for polishing nitrate-contaminated waters. We compared raw cyanobacterial biomass (Leptolyngbya sp.) with its hydrochar produced by hydrothermal carbonization. Despite an approximately tenfold increase in BET area after carbonization (4.08 vs. 0.5 m² g⁻¹), the hydrochar performed worse than the native material under all tested conditions. Batch tests (C₀ = 20 to 100 mg N L⁻¹; dose = 0.067 g L⁻¹) reached equilibrium within 25 min, achieving removal rates ranging from 40% up to 56%. Nonlinear fits showed that the pseudo-first-order model simulates the time courses with physically consistent parameters, while the equilibrium data in the studied window were represented by the Freundlich isotherm. In fixed-bed trials, the biomass treated 58 bed volumes to the nitrate-N compliance value of 11.3 mg N L⁻¹, compared with 27 bed volumes for the hydrochar; the breakthrough profiles were modeled using the Yoon–Nelson equation and nonlinear regression. Over the conditions examined, performance tracked surface chemistry and charge characteristics rather than area, consistent with contributions from specific interactions and uptake within the cellular matrix. These results support minimally processed cyanobacterial biomass as a practical option for energy-lean nitrate polishing under the frame of the circular economy.