Environmental Technology最新文献

Excessive phosphorus discharge into lacustrine systems was recognized as a primary factor for eutrophication, significantly disrupting the ecological equilibrium of freshwater ecosystems. Effectively controlling endogenous phosphorus release from sediment reservoirs constitutes a fundamental prerequisite for mitigating this environmental challenge. In this study, a sediment microbial fuel cell (SMFC) was developed to address the challenges of sediment-bound phosphorus mobilization. Sediment Total Organic Carbon (TOC) removal in CC-FA-0.2 yielded 2.25 times greater than the control, indicative of aromatic and fulvic acid degradation. Phosphorus in interstitial water decreased by 66% in closed-circuit (CC) reactors, with sequential fractionation revealing enhanced iron-bound phosphorus (BD-P) retention in sediment (105% increase in CC-FA-0.05 vs. versus control). Fe(Ⅲ) redox cycling under SMFC operation maintained higher Fe(Ⅲ) retention (58-54% vs. 51-52% in open-circuit), critical for phosphate immobilization. Microbial profiling identified Proteobacteria (20.41%) and Desulfobacterota (20.41%) as dominant phyla, with genera like Geobacter and Sideroxydans synergistically driving Fe(Ⅲ)/Fe(Ⅱ) cycling and extracellular electron transfer. This study establishes a novel bioelectrochemical strategy based on fulvic-iron synergy, which drive a sustainable electrode-iron-humus redox cycle. This process offers a highly effective and sustainable approach for the simultaneous immobilization of sediment phosphorus and removal of organic pollutants in situ.

A laboratory-scale anaerobic membrane bioreactor (AnMBR) for landfill leachate (LFL) was operated to investigate the effects of nano zero-valent iron (nZVI) (without nZVI addition, 50-300 mg/L) on contaminant removal and membrane fouling. nZVI can be a potential additive to improve AnMBRs' performance by regulating LFL treatment, microbial community structure, and especially membrane fouling. Therefore, this study evaluated the role and effectiveness of nZVI in enhancing AnMBRs' performance for wastewater treatment and membrane fouling mitigation. Results show that nZVI addition could improve AnMBR performance in removing pollutants and reducing membrane fouling. The optimal condition was found to be nZVI at 100 mg/L, corresponding to a membrane fouling rate of 0.012 mbar/min. However, since membrane fouling rate worsens at higher concentrations, the optimal nZVI concentration for pollutant removal was determined to be 200 mg/L. The results indicated removal efficiencies of 68% for chemical oxygen demand (COD), 31% for colour, and 47% for dissolved organic carbon (DOC). As a result, transmembrane pressure (TMP) decreased by 68%, and permeate flux showed a slight improvement at 100 mg/L nZVI. Additionally, adding nZVI reduced the ratios of protein to polysaccharide in both extracellular polymeric substances (EPS) and soluble microbial products (SMP), thereby mitigating membrane fouling. Firmicutes, Bacteroidetes, and Proteobacteria, which showed relatively high abundance, played important roles in pollutant removal in LFL. Also, bacteria associated with membrane fouling were identified as Alphaproteobacteria, Sphingobacteria, and Flavobacteria in the AnMBR. Results indicate that nZVI addition can enhance AnMBR performance in both pollutant removal and membrane fouling reduction.

Membrane filtration is a safe and sustainable water treatment method; however, membrane fouling remains a major challenge that limits its broader application. Modified membranes for fouling mitigation have been extensively studied, including photocatalyst incorporation for organic matter degradation and biofouling control. However, no commercially available photocatalytic membranes exist to date, possibly owing to the lack of understanding of their properties. Furthermore, conventional microbiological test methods commonly used in membrane research are insufficient for accurately assessing membrane antibiofouling properties. Mixed-matrix dual-layer membranes with varying concentrations of zinc oxide nanoparticles were prepared and characterized using multiple testing approaches. Despite achieving >99.999% reduction in cultivable Escherichia coli, viability assays revealed that only half of the cells were dead, with the rest entering a viable but nonculturable (VBNC) state and forming microcolonies, resulting in misleading CFU-based results. Additionally, Pseudomonas aeruginosa biofilm formation was evaluated using fluorescence staining to assess extracellular polymeric substance (EPS) production. While P. aeruginosa survived and multiplied on the photocatalytic membranes, biofilm maturation was inhibited, with EPS protein production reduced by up to 84% compared with the unmodified reference.

This study developed a sustainable bio-adsorbent derived from rice straw carboxymethyl cellulose (CMC) and evaluated its efficiency in improving canal water quality for agricultural reuse. The synthesized CMC exhibited high solubility with a degree of substitution of 0.67. Batch adsorption experiments identified optimal conditions for manganese (Mn²⁺) removal at pH 6, 2.0 g L⁻¹ dosage, and 10 min contact time, achieving 97.0% removal efficiency and an adsorption capacity of 10.54 mg g⁻¹. The adsorption process followed the Freundlich model (R² = 0.9501), indicating heterogeneous multilayer adsorption. To assess field applicability, a pilot-scale multi-stage filtration system - comprising sand, activated carbon, and CMC columns - was operated for 101 days at the Rangsit Prayurasak Canal. The system effectively reduced BOD₅ (85.4% ± 4.5%), Mn²⁺ (81.5% ± 3.6%), chloride (48.7% ± 3.68%), and salinity (46.3% ± 9.8%), producing treated water that met Thailand's Type III surface water standard for agricultural reuse. This work is the first to demonstrate the field-scale use of rice straw-derived CMC in a modular filtration system under actual canal conditions. The results highlight the dual benefits of agricultural waste utilization and practical water quality improvement, offering a technically feasible and low-cost solution for decentralized water treatment in agricultural communities.

ABSTRACTThe volumetric oxygen mass transfer coefficient ($k_{L}a$) is a critical parameter in the design, scale-up, and operation of bioreactors. In this study, a fully automated dynamic method was developed for determining $k_{L}a$, eliminating manual intervention and ensuring reproducible and reliable estimates. The approach includes a probe response-time correction and was validated under different operational conditions in an aerated stirred system. The influence of two representative pollutants was evaluated: phenol and benzalkonium chloride (BAC). While phenol produced a small enhancement (≈18%) of the overall $k_{L}a$, BAC caused a reduction in $k_{L}a$, mainly due to its pronounced effect on the surface mass transfer coefficient ($k_L{a}_S$). To the best of our knowledge, this work provides the first experimental evidence of BAC effects on oxygen transfer in bioreactors. These results expand the current understanding of how pollutants can simultaneously act as metabolic inhibitors and as modifiers of gas-liquid mass transfer, with significant implications for optimising aeration strategies in biological wastewater treatment.

Lignite is not suitable as fuel due to its high moisture and ash content and low combustion efficiency. However, the high organic matter content of lignite makes it a potential raw material for microbial decomposition and hydrogen production. Hydrogen production has always been a technical challenge faced worldwide. This study used lignite as the reaction raw material to investigate the influencing factors of microbial hydrogen production, with a focus on the effect of fulvic acid, the main chemical component in lignite, on the microbial conversion of lignite for hydrogen production. By measuring the daily hydrogen production, total hydrogen production, and the content changes of humic acid and pyruvic acid in the reaction system of hydrogen produced by microorganisms in lignite, combined with spectral characteristic analysis, the mechanism of fulvic acid in hydrogen production from lignite was revealed. The research results show that the addition of fulvic acid can significantly improve the hydrogen production efficiency of lignite, especially when the addition amount is 100 mg/L, the promoting effect is the most obvious. The total hydrogen production reached 2.140 mL/g, which was 1.44 times that of the control group.

This study aims to enhance biogenic elemental sulfur (S⁰_bio) recovery efficiency in Simultaneous Nitrogen and Sulfur Removal (SNSR) processes for dual environmental and economic benefits. The addition of thiosulfate to redirect reaction pathways in a Thiobacillus denitrificans-augmented SNSR system elucidates its regulatory mechanism on S⁰_bio yield and stability. Under low sulfide loading (100 mg/L S^2-), 30 mg/L S₂O₃^2- amendment achieved peak S⁰_bio yield of 69.85% at 36 h, with sulfur conversion efficiency 3.03-fold higher than the high-loading non-inhibited group (NI). The target pathway (S^2-→ S⁰_bio) intensity increased by 0.53-1.05-fold, while the competing pathway (S^2-→ S₂O₃^2-) was inhibited (0.10-0.28-fold reduction). Thiosulfate enabled the S⁰_bio generation pathway to dominate over S^2-→ SO₄^2-during early-stage low-sulfide SNSR, reaching a maximum contribution of 55.32%. Additionally, the fluorescence intensity contribution of soluble microbial products (SMP) reached a peak of 49.81%, while concurrent measurements showed significant increases in viable cell count and viability (averaging 2.17-fold and 3.18-fold higher than those in the non-thiosulfate-amended groups, respectively). Thiosulfate synergistically drives efficient S⁰_bio stabilization through dual mechanisms: (1) enhancing Thiobacillus denitrificans bioactivity to intensify key reaction kinetics; (2) optimizing sulfur speciation transformation to establish target-pathway dominance. This work provides technical insights for resource recovery from sulfur-laden wastewater and stable S⁰_bio reclamation.HighlightsEarly-stage inhibition boosts S⁰_bio yield to 69.85% at low sulfide loading with thiosulfate amendment.3.03× higher sulfur conversion efficiency versus high-loading controls via pathway redirection to S⁰_bio generation.Dual regulation: Synergistically enhances Thiobacillus denitrificans activity (↑1.22× viability) and redirects sulfur flux toward S^2-→S⁰_bio (55.32% dominance), suppressing competing pathways.Resource recovery strategy enabling stable S⁰_bio reclamation from sulfur-laden wastewater.

To fully exploit the potential of drinking water treatment residue (DWTR) for mitigating excessive nitrogen (N) and phosphorus (P) discharges responsible for water eutrophication, a straightforward precipitation process was used to produce Mg(OH)₂-modified drinking water treatment residue (Mg-DWTR). The resulting material can simultaneously remove N and P and exhibit high adsorption capacity. The effects of solution pH, adsorbent dosage, reaction time, initial concentration and coexisting substances on the simultaneous removal of ammoniacal nitrogen (NH₄⁺-N) and total phosphate (TP) by Mg-DWTR were assessed. Mg-DWTR exhibited high removal capacity across a broad pH range (3-9). The adsorption process applied both pseudo-second-order and Langmuir kinetic models, with predicted maximum adsorption capacities of 43.771-50.295 mg g^-1 (NH₄⁺-N) and 82.050-89.881 mg g^-1 (TP), the adsorption process is exothermic. After five reuse cycles, Mg-DWTR retained adsorption capacities of 8.541 mg g^-1 for NH₄⁺-N and 20.511 mg g^-1 for TP. Additionally, the adsorption capacity of Mg-DWTR was markedly suppressed in the presence of K⁺, SO₄^2-, citric acid, and humic acid. SEM-EDS, XRD, and FTIR analyses before and after adsorption revealed multiple mechanisms governing the adsorption process. Among these, the primary removal pathway for NH₄⁺-N and TP is due to the formation of struvite crystals. Additionally, ligand exchange, electrostatic attraction, and physical adsorption synergistically enhance the removal of nutrients. This work provides fresh insights into N and P removal in aquatic environments and the resource utilisation of DWTR, realising the concept of 'using waste to treat waste'.

Pond systems represent the simplest and most widely used technology for treating high-strength wastewater containing biodegradable suspended solids. When covered, they offer advantages such as odour control, intensified organics degradation, and biomethane capture. However, their efficiency is often limited by unmixed zones and the formation of floating or sinking layers, which reduce residence times and treatment performance. Here, we developed a novel mixing concept for anaerobic pond systems and systematically tested its mixing efficiency. The novel mixing concept avoids permanently installed mechanical components and instead relies on a planar, kite-like mixing tool that is moved horizontally through the pond by an external rope-guided system. This design enables flexible, low-maintenance operation with minimal energy input and is particularly suitable for shallow, large-scale ponds where conventional submerged mixers are impractical. Three different mixing tool designs were evaluated using dye and conductivity tracer experiments with model substates in a 330 L pilot-scale pond. All tools were based on perforated planar plates with identical open area ratio (44 %), but differed in hole geometry. The effect of substrate viscosity was assessed at two distinct velocities. Results showed that increasing viscosity significantly prolonged the mixing time, while doubling the mixing velocity reduced it by a factor of four. The mixing tool design strongly impacted flow patterns and therewith the mixing efficiency. Findings were integrated into an operation scheme for full-scale anaerobic pond systems equipped with planar mixing tools that accounts both for the mixing performance and the economic efficiency.