Environmental Technology最新文献

ABSTRACTThe volumetric oxygen mass transfer coefficient () 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.

Wet and dry atmospheric deposition plays a crucial role in the removal of airborne pollutants, being influenced by both meteorology and chemical composition. While these processes occur on intra-event (hourly) time scales, most existing monitoring approaches rely on daily or event-based sampling, which limits our understanding of short-term variations in gas scavenging and pollutant deposition. Here, we present the development and application of R-WASH (RainWater Automatic Sampler Hardware), a low-cost, open-source, and semi-automatic device for high-resolution (hourly) rainwater sampling. The system consists of modules for collection, distribution, and storage (up to 24 bottles). We tested the system in nine rainfall events, in which 91 hourly samples were collected and analyzed for ammonium, nitrite, nitrate (via spectrophotometry), and particulate-bound metals (Cd, Cu, Cr, Ni, Zn) using acid digestion and atomic absorption spectroscopy. Recovery tests confirmed high sampling efficiency and chemical integrity. The data revealed distinct temporal behaviours: particulate metals showed peak concentrations during the initial hours of rain events, while nitrogen compounds displayed quasi constant concentration throughout. Correlation analysis showed that metals were positively associated with PM and negatively with temperature and time step, suggesting strong links to particulate-mediated deposition and early-stage scavenging. In contrast, nitrogen species showed weaker and more variable correlations, likely due to their higher solubility and continuous atmospheric input. The performance of regression models improved with increasing bin width, particularly for metals Cu and Zn (R² > 0.85 under 5-hour binning). These findings highlight the value of high-resolution sampling in understanding the deposition processes.

Coal chemical wastewater, characterized by high toxicity, salinity, and refractory organics (e.g. phenols), poses significant environmental challenges. An innovative system integrating micro-nano bubbles (MNBs) and acclimated bacterial consortia (DP-1) was developed in this study. It was designed to achieve efficient phenol degradation and chemical oxygen demand (COD) removal. DP-1 was domesticated under MNBs aeration, high phenol (up to 400 mg/L), and high-salt (1-15 g/L) conditions, exhibiting remarkable adaptability. The MNBs@DP-1 system achieved 100% phenol degradation and 88.9% COD removal within 24 h at 600 mg/L phenol, demonstrating robust performance across a wide pH range (6-9) and salinity (1-15 g/L). Notably, in a sequencing batch biofilm reactor (MNB-AR), long-term treatment of actual coal chemical wastewater (COD: 1300-1600 mg/L) yielded a stable average COD removal of 76.2% with <1.6% fluctuation. Microbial community analysis revealed Proteobacteria (99.1%) dominance post-acclimation, with Acinetobacter (65.7%) and Comamonas (29.7%) as key functional genera driving phenol mineralization. Comparative studies confirmed the superior efficacy of MNBs@DP-1 over conventional aeration systems, attributing enhanced degradation to MNBs-induced bacterial activity and biofilm stability. This work provides a scalable strategy for achieving 'zero discharge' in coal chemical wastewater treatment by synergizing bubble technology and microbial acclimation.

The slow formation of simultaneous anammox and denitrification (SAD) granular sludge remains a major challenge for its practical application. This study developed a novel strategy for rapid cultivation of SAD granular sludge in lab-scale UASB reactors using synthetic wastewater and municipal sludge as inoculum. By introducing a recirculation system, we significantly enhanced sludge granulation, system stability, and nutrient removal performance. The recirculation-enabled reactor (R1) achieved over 90% removal of nitrogen and COD, promoted the secretion of extracellular polymeric substances (EPS), and increased the abundance of key anammox bacteria (Candidatus Kuenenia). Microbial and functional genes analyses revealed that recirculation up-regulated functional genes related to denitrification and granulation, improving both structural integrity and process efficiency. These findings demonstrate the effectiveness of recirculation in accelerating SAD sludge granulation and stability under controlled conditions. This work provides a feasible approach for optimizing SAD start-up and provide valuable insights into optimizing SAD granulation strategies, with important implications for energy-efficient nitrogen removal in wastewater treatment.

Extracellular polymeric substances (EPS) play a vital role in forming microbial aggregates such as biofilms, flocs, and granules. However, standardised methods for extracting EPS from the activated sludge across different wastewater treatment processes remain elusive. The anaerobic-anoxic-oxic (A²O) process, widely used in wastewater treatment, was selected to investigate EPS extraction from its activated sludge. This study compared twenty-five physicochemical methods for EPS extraction from the activated sludge collected from the secondary sedimentation basin of an A²O reactor, evaluating EPS yield, composition, and cell lysis. The results show that combined chemical-physical extraction methods, particularly NaOH/heat treatment, achieved higher extraction rates while preserving EPS characteristics. This method yielded higher concentrations of proteins (PN) and polysaccharides (PS) with reduced cell lysis compared to other techniques. In most methods, protein content exceeded polysaccharides content, with PN/PS ratios ranging from 0.005 to 4.17 g/g. Higher PN/PS ratios were associated with smoother, more uniform EPS morphology. Particle size distribution of the treated sludge showed minimal variation between methods. Fourier transform infrared (FTIR) and excitation emission matrix (EEM) fluorescence spectroscopy confirmed the presence of proteins, polysaccharides, and DNA in EPS, with NaOH/heat treatment more effectively preserving functional groups. Optimisation tests identified 45 min as the ideal heating duration for maximum EPS extraction. Overall, this study provides a systematic evaluation of EPS extraction methods from the activated sludge in A²O systems, offering methodological insights for future wastewater treatment research.

This study aimed to evaluate the bioleaching of copper from discarded printed circuit boards (PCBs) using the fungus Aspergillus tubingensis UCP 1208 as a sustainable and environmentally friendly alternative for the recovery of valuable metals. The methodology included the acclimatization of the fungus to different concentrations of crushed PCBs, followed by bioleaching assays and copper removal analysis through scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and inductively coupled plasma optical emission spectrometry (ICP-OES). SEM-EDS analyses revealed significant changes in the morphology and elemental composition of the PCBs after treatment, confirming the efficiency of copper solubilization. Quantitative results indicated that A. tubingensis, acclimatized with 1% (w/v) of crushed PCBs, removed 494.2 mg L⁻¹ of copper for a PCB load of 1 g L⁻¹, representing a 335.5% increase in removal compared to conventional acid digestion. These results demonstrate that bioleaching with A. tubingensis is a viable, efficient, and sustainable approach for the recovery of metals from electronic waste, offering a cleaner alternative to traditional chemical methods by avoiding the use of aggressive acids and contributing to circular economic practices.

New strategies for effluent treatment aimed at reducing environmental pollutants have significantly advanced, particularly biological methods involving enzymatic processes. In this context, this study evaluated the efficacy of a laccase-enriched enzymatic extract (specific laccase activity = 0.45 U/mg), obtained from the fungus Xylaria sp. for treating pharmaceutical effluents containing paracetamol, diclofenac, mefenamic acid, ibuprofen, and sulfamethoxazole, each at concentrations of 50 ppm. The enzymatic treatment resulted in notably higher degradation efficiencies for paracetamol and mefenamic acid under initial screening (∼70%). These drugs were selected for optimization due to their higher susceptibility to enzymatic degradation and because they are widely consumed pharmaceuticals frequently detected in aquatic environments. Afterward, optimization studies focused on these two pharmaceuticals, employing a statistical experimental design to determine optimal conditions, identified as pH 6.7, temperature of 40°C, and exposure time of 4.5 h. Under these optimized conditions, experimental results indicated a 95.55% reduction in paracetamol and a 55% reduction in mefenamic acid concentrations.Furthermore, enzyme immobilization on chitosan significantly enhanced stability and performance, maintaining approximately 90% reduction of both pharmaceuticals after multiple treatment cycles. These findings highlight the effectiveness of immobilized laccase systems and optimized reaction parameters, supporting their potential application for sustainable and efficient treatment of pharmaceutical effluent. Importantly, this work represents the first demonstration of using Xylaria sp. as a laccase source for pharmaceutical degradation, underlining its novelty and potential.

PES/PVP membranes are widely used at industrial scale for skim milk ultrafiltration aiming at protein content standardization. Membranes are systematically fouled by proteins which are removed twice a day using formulated detergents among which enzymatic detergents often appear to be an eco-friendly solution. In this study, proteases called subtilisins, are selected and incorporated into a detergent formulation whose only variable was the source of subtilisin. Since liquid enzymes are commercially available in stabilized form, this allows to focus on the role of stabilizing agents on cleaning performance, even at very low concentrations. The selected UF membrane (HFK-131, Koch) has been fouled by skim milk at 50°C. Then, the cleaning efficiency of the prototype detergents was evaluated at 50°C from the residual protein quantified on membrane by ATR-FTIR. With equivalent enzymatic activity, detergents based on each one of the three selected enzyme sources, removed at least 95% of the proteins present at start evidencing the high cleaning efficiency. Simultaneously, the water flux recovery post-cleaning ranged from 1.9 to 3.8 requiring detailed and complex analysis to interpret this value greater than 1. Aiming at such understanding, a de-formulation approach was undertaken, combined with complementary ATR-FTIR characterization of membranes at every step. The discussion provides an explanation of the WFR behaviour likely associated with the variation in membrane hydrophilicity resulting to detergent ingredient adsorption. Besides the role of one given surfactant of the formulation, the impact of enzyme stabilizers was also demonstrated with possible synergetic effects with other ingredients.

Aqueous contamination by arsenic and antimony has become a significant concern due to its prevalence in smelting activities. Nowadays, adsorption stands out as an effective method for the removal of these heavy metal ions from water, particularly when the goal is to achieve high levels of purification and ensure safety. However, the complex nature of smelting wastewater often leads to a decrease in the selectivity and salt resistance of adsorbents under industrial conditions. In this study, we introduce a novel designated composite-resin material (KYE003), which is tailored for the deep purification of arsenic and antimony. By precisely adjusting the synthesis ratios, we have controlled the intrinsic kinetics of material synthesis, enabling the in-situ loading of ferric oxide onto the resin surface, coupled with organic functional groups (-COOH and -SH). The resin's inherent porous structure not only promotes the nucleation and growth of amorphous iron oxide but also establishes a quantitative basis for nano-scale binding sites. Further surface characterisation analysis indicates that interfacial functional groups, including (-COOH, -SH, and -OH), are instrumental in the complexation of arsenic and antimony. The synergistic interactions, such as -O-As/Sb, -COO-As/Sb, and -S-As/Sb, demonstrate that the hybridisation of these groups restructures the interfacial electronic state, thereby enhancing the adsorption performance. The KYE003 material exhibits exceptional adsorptive selectivity and chemical stability under complex conditions, capable of maintaining arsenic concentrations in the effluent below 20 µg·L^-1 until the bed volumes ratio surpasses 6240. This research presents a new perspective for the deep purification of heavy metal ions.

Vermicomposting has been proven to be effective in combating tetracycline resistance genes (TRGs) in organic waste, such as animal manure and sewage sludge. However, the influences of tetracycline resistant bacteria (TRB) in organic waste during earthworm conversions on the fate of TRGs remain poorly understood. Hence, we prepared diets treated with either sensitive or insensitive tetracycline resistant bacteriome (STRB or ITRB) to earthworm midgut fluid and investigated the fate of bacterial communities and TRGs (including tetB, tetC, tetZ, tetL, and tetX) and their response to tetracycline during earthworm conversions in a controllable environment. Results showed that the bacterial composition of casts was highly complex, yet diet-derived bacteria were either minimal or undetectable. Notably, TRGs abundance in casts was dramatically higher than that in diets, indicating that the earthworm gut is a hotspot for TRGs dissemination. Furthermore, the increase in TRGs abundance was more pronounced in casts treated with ITRB compared to those treated with STRB, and this increase was suppressed by tetracycline exposure in casts treated with ITRB. This phenomenon may be due to the fact that diet-derived TRB and/or tetracycline alter the microbial community (e.g. relative abundance of Aeromonas). In conclusion, this study highlights the diet-derived TRB amplify the hotspot effect of earthworm gut on tetracycline-resistance gene dissemination, but regulated by tetracycline.