Environmental Technology最新文献

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.

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.

As urbanization accelerates, the issue of pollutant discharge from building materials has become the focus of public attention. Conducted in a ventilated environmental chamber, the experiments investigated the emission characteristics of VOCs from dry and wet building materials, focusing on the influencing factors, such as temperature, relative humidity (RH), ventilation, and seasonality. The impact of influencing factors was quantified using a one-factor-at-a-time control method. This study establishes that environmental factors - temperature, RH, air exchange rate (AER), and seasonality - significantly influence VOC emissions from building materials. Elevated temperature and humidity consistently increase emission rates and concentrations, while higher AER reduces indoor VOC levels. Emissions peak rapidly upon material installation, decline sharply, and stabilize within predictable ranges. Seasonal variations show summer (high temperature/RH) yielding maximum emissions, contrasting with winter minima. Dry and wet materials exhibit similar emission trends, though temperature exerts a stronger effect on formaldehyde release from dry materials, while RH elevates peak and stable concentrations for wet materials. AER demonstrates dual effects: promoting initial emissions while diluting concentrations long-term, warranting further investigation. The C-history method efficiently determines initial emittable concentrations, and validated predictive models accurately forecast steady-state emissions across varying conditions. These models reliably estimate long-term pollutant levels using short-term data, proving valuable for indoor air quality assessment, material selection, and ventilation design. The study provides valuable insights into the practical significance of temperature, RH, ventilation, and seasonality on the emission rates of formaldehyde and TVOC from building materials.

Food waste (FW) has high production potential that can be converted into renewable energy in the form of biogas during anaerobic digestion (AD). Batch tests under mesophilic (37℃) disgestion were performed to evaluate the effects of different dosage ratios (10-35%), salts (0-20 g·L^-1) and oil content (0-20 g·L^-1) on methane (CH₄) production, process stability and organic reduction during the AD. The results showed that optimal CH₄ occurred at a dosage ratio of 20%, while ratios > 30% caused inhibition. Salt (<5 g·L^-1) enhanced AD efficiency, peaking at 314.75 mL CH₄ production g VS^-1 (1 g·L^-1 salt), whereas > 15 g·L^-1 salt suppressed methanogenesis. Oil at 15 g·L^-1 maximized methane yield (393.66 mL CH₄ production g VS^-1) with 12-day digestion, while 20 g·L^-1 oil induced inhibition. Excessive organic loading rate (OLR) (>3.0 g VS/L/d) triggered the accumulation of Volatile Fatty Acids (VFAs) > 20,000 mg/L and an acidification pH = 5.94, collapsing biogas production; recovery via pH adjustment, starvation, and sludge inoculation reduced VFAs by 96-100%, restoring stable biogas output (0.63-2.09 L/L/d) with neutral pH = 7.35 and 65% methane content. Microbial synergy and VFA degradation ensured system resilience under safe OLR ≤ 3.0 g VS/L/d, highlighting FW's viability for renewable energy recovery.

This research investigates the behavior of key components within aerobic and anoxic bioreactors in Biological Nitrogen Removal (BNR) bioprocesses. A mathematical model based on the Modified Ludzack-Ettinger (MLE) configuration is proposed. The model comprises an ensemble of ten differential equations derived from mass balances in the MLE system, complemented with a set of biokinetic models. To reduce complexity and enhance applicability, the model treats all nitrogen and phosphorus compounds as atomic N and P, and aggregates carbon sources as Chemical Oxygen Demand (COD), eliminating the need for tuning complex compound-specific parameters. The model was calibrated and validated using analytical determinations of nitrogen, phosphorus, COD, dissolved oxygen, and biomass concentrations from experiments conducted with synthetic wastewater in aerobic and anoxic reactors. Complementing this, a metagenomic study characterized the diversity and relative abundance of taxonomic groups involved in nitrogen and phosphorus metabolism within the microbial communities. Utilizing biokinetic and stoichiometric parameters for the entire microbiota, the model can be solved for both transient and steady-state conditions across a range of operational variables. It enables the estimation of bioprocess resilience following disturbances and the subsequent recovery time to a new steady state. A one-at-a-time (OAT) sensitivity analysis identified the parameters most significantly affecting state variables. The experimental results confirm the model's validity and reliability in simulating BNR processes.

This study presented a strategy for rapid establishing partial nitritation using autotrophic nitrifying granular sludge (ANGS), offering a green and efficient solution for treating ionic rare earth mining wastewater, which is characterised by acidic pH, low organic content, and elevated ammonia nitrogen. Experiments were conducted in a sequencing batch reactor (SBR) inoculated with stored granules. By Day 8, the ANGS demonstrated excellent recovery of activity, with the nitrite accumulation rate (NAR) exceeding 90%. Through controlled aeration intensity, the ammonia oxidation rate and nitrite oxidation rate of the ANGS were leveraged to regulate aeration time. A NO₂^--N/NH₄⁺-N ratio of approximately 1.32 was firstly achieved by Day 25 when the nitrogen loading rate (NLR) was 0.24 kg/m³·d, and partial nitritation was also achieved by Days 41, 54, 70 and 85 respectively when the NLRs were 0.30, 0.36, 0.42, and 0.48 kg/m³·d. Ammonia oxidising bacteria (AOB) remained highly active, while nitrite oxidising bacteria (NOB) were effectively suppressed. By the conclusion of the experiment on Day 90, the dominant microbial communities in the reactor were Nitrosomonas (20.32%), Thauera (12.57%), and OLB8 (10.60%). Metagenomic analysis revealed a significant enhancement in the relative abundance and activity of amoC (encoding ammonia monooxygenase) and hao (encoding hydroxylamine oxidoreductase) in AOB. The calculated conversion costs for different NLRs per cycle were 4.646, 6.845, 8.901, 9.538 and 10.222 RMB/m³.

Atmospheric emissions inventories are a key tool for environmental managers, providing insights into emission sources and their effects on air quality, health, and climate. This study develops the atmospheric emissions inventory for four major industrial sectors in Brazil with a bottom-up approach, available at https://github.com/Martins-UTFPR/Brazil-s-industrial-emissions-inventory. We quantified atmospheric emissions from refining crude oil, producing cement, pulp and paper, and generating electricity by thermoelectric plants using biomass, gas, oil, and mineral coal. The quantification of atmospheric emissions and the standardization of the calculation matrices, processed using R code, follow the guidelines defined by the United States Environmental Protection Agency (EPA) and the European Environment Agency (EEA). The highest emission rates are in the country's southeastern region, specifically in outlying areas of the São Paulo state. In 2019, more than 50% of the estimated emissions are associated with electricity generation with contributions of 4.85 GgBC yr^-1, 22.40 GgCO yr^-1, 159.11 GgPM₁₀ yr^-1, 132.42 GgPM_2.5 yr^-1, 87.17 GgNMVOC yr^-1, 360.90 GgNO_x yr^-1, 182.94 GgTSP yr^-1, and 596.33 GgSO_x yr^-1. The production of fuels and oil derivatives is the second source of emissions with the highest contribution, despite operating 17 refineries in the country. Further, the comparison with the EDGAR inventory indicates consistency, although it shows higher values for some pollutants and sectors, as well as certain spatial differences. Finally, at National level, the magnitude of emissions is comparable to those from road transport. Thus, this study provides a region-specific and detailed emission inventory, offering crucial insights for both the scientific community and environmental agencies in improving air quality management.

In-situ bacterial remediation has shown substantial potential for decommissioned uranium mining areas. Our previous research indicated that the similar redox potentials of Fe(III)/Fe(II) and U(VI)/U(IV), along with iron's significance in bacterial growth and metabolism, provide a basis for synergistic uranium remediation. This study investigated the impacts of diverse electrode voltages on U(VI) immobilisation by Leifsonia sp. in an iron-sulfur co-existing system. Bacteria immobilise U(VI) by adsorption. SEM-EDS and XPS analyses confirmed that electro-stimulated bacteria (under applied voltage) reduced U(VI) to U(IV), forming Fe-U complexes. For comparison, under open-cell conditions (i.e. the electrochemical cell was in an open-circuit state without applying any external constant voltage), U(VI) removal was negligible. The optimal voltage (3.0 V) enhanced U(VI) removal via bacterial adsorption and incorporation into Fe-S compounds. However, too high a voltage hindered U(VI) removal.

Aerobic co-composting represents an effective method for the treatment of antibiotic fermentation residues. This study optimized the co-composting of abamectin mycelial dregs (AMDs), excess sludge, and maize straw using an orthogonal experimental design. Composting was performed at a mass ratio of 4:1:1 (dry weight) under varying initial C/N ratios (20:1-30:1), moisture contents (50%-70%), and microbial inoculant dosages (5%-15%). Key parameters monitored included physicochemical properties, abamectin removal efficiency (RRA), and residual abamectin levels in the final product. The treatment with C/N = 30:1, moisture content = 60%, and inoculant dosage = 5% resulted in the longest thermophilic phase (6 days), highest temperature (59°C), highest germination index (90.05%), and highest RRA (89.67%), along with the lowest final moisture (24.95%) and residual abamectin (0.34 mg/g). Multivariate analysis of variance indicated that initial C/N, moisture, and inoculant dosage significantly influenced compost properties and abamectin degradation. Range analysis further identified the optimal conditions as C/N = 30:1, moisture = 70%, and inoculant = 5%. Microbial diversity analysis revealed key genera involved in the process, including Saccharomonospora, Bacillus, Kroppenstedtia, and Aspergillus. This study confirms the feasibility of aerobic co-composting for AMD treatment and offers new insights into its microbial mechanisms.

The preparation of activated carbon derived from municipal sludge and amino modification for CO₂ adsorption can not only achieve the resource utilization of sludge but also address the issue of CO₂ emission reduction. Municipal sludge was used in this study as a raw material to prepare CO₂ adsorbents via pyrolysis, activation, and amino modification. Microstructural characterization and CO₂ performance tests were conducted to analyze the influence of different activation agents, pyrolysis temperature, and pyrolysis time on the microstructural evolution and CO₂ adsorption performance of sludge-based activated carbon. The results indicate that the solid NaOH activator enabled the sludge to generate more pore structures. When the pyrolysis temperature was 600°C and the pyrolysis time was 60 min, an excellent pore structure was obtained. Nevertheless, an excessively high pyrolysis temperature and time would cause sintering of the samples, leading to pore collapse. Under the aforementioned preparation conditions, the sludge-activated carbon reached its maximum CO₂ adsorption capacity, with the maximum adsorption capacity of CO₂ being 1.369 mmol/g. The adsorption temperature had a significant influence on the final adsorption effect, and the optimal adsorption temperature is 25°C.