Environmental Technology最新文献

Dairy manure, a significant source of phosphorus (P), can potentially cause environmental risk due to P runoff when dairy manure is directly applied to cropland. Thus, there is an increasing interest in mitigating P loss from manure prior to land applications. This study aimed to investigate the potential of hydrochar produced by hydrothermal carbonization (HTC) for P recycling from dairy manure with and without the addition of CaO, focusing on the plant bioavailability, stabilization, and transformation of P in the resultant hydrochar. Hydrochar was prepared under different temperatures (180-240°C). The effect of CaO addition (0-10% of raw manure on dry wt. basis) was also evaluated at 220°C. Results showed that water-soluble P (WSP), a key indicator of P runoff loss, was significantly reduced in hydrochar, particularly with CaO addition. In addition, the plant available P in hydrochar increased with HTC temperature increase till 220°C, which accounted for ∼90% of total P content, then decreased with temperatures higher than 220°C. The addition of CaO slightly reduced plant bioavailability when compared to hydrochar produced at 220°C without additive. The P fractionation and speciation analyses indicated the transformation of P into Ca-associated apatite P. Hydrochar produced at 220°C with 10% CaO addition resulted in a high P recovery (∼85%) and a reduced runoff risk by 97%. The results demonstrate the efficacy of P recycling through hydrochar produced from dairy manure through HTC, which offers a sustainable approach to managing dairy waste while mitigating the potential environmental risks of P runoff.

Dexamethasone (DXM) was the first drug used to treat COVID-19, only a small part is metabolized and has been identified in wastewater and surface water, conventional treatments do not remove these compounds, therefore new technologies must be developed. A commercially injectable solution containing dexamethasone (DXM) was removed by heterogeneous sono/photo-Fenton (SPF) process using clinoptilolite zeolite (CZ) modified with Fe (CZ-Fe) by an electrodeposition method. The effect of initial concentration (1.2, 3, 5.5, 8, 9.7 mg/L), H₂O₂ dose (9.8, 15, 22.5, 30, 35.1 mg/L) and hydraulic retention time (HRT, 39.5, 60, 90, 120, 140 min) were evaluated through central composite design (CCD). The frequency of the ultrasound was 140 kHz. The optimal conditions were 5.5 mg/L DXM, 22.5 mg/L H₂O₂ and 140 min obtaining an 85.4% DXM by UV-Vis, 99% by high-performance liquid chromatography (HPLC) and 76% by chemical oxygen demand (COD) removal. The systems generated 12, 25, 40.5 and 45.5 mg/L of total oxidant at 20, 60, 100 and 140 kHz, respectively. In individual effects, UV radiation removed 23.6%, ultrasound 18.1% and H₂O₂ 14% of DXM. In kinetic studies, the best fit was obtained for the Behnajady-Modirshahla-Ghanbery (BMG) model. SPF improved the mass transfer within the reaction media, the oxidation rate and the consumption of H₂O_2, and no sludge was generated. Finally, another oxidant formed during the process (H^•, HO₂^•, O₂^-•) contributed to DXM removal.

The valorization of agro-industrial by-products/co-products represents a sustainable pathway to produce high-value biomaterials. Feather meal is an agro-industrial co-product derived from clean and undecomposed poultry feathers processed under high heat and pressure that offers an economically viable and scalable alternative for keratin extraction compared to native feathers. This study explores the recovery of keratin from feather meal through an optimized alkaline hydrolysis process, achieving a yield of 20 wt.% at 15°C and 90 min of extraction by using 2 mol L^-1 sodium hydroxide solution. A negative temperature dependence was observed in keratin extraction yield, suggesting the occurrence of thermal degradation at elevated temperatures. Protein analyses by different techniques confirmed the characteristic diffraction peaks, functional groups, and elemental composition (carbon, nitrogen, oxygen, and sulphur) of feather keratin. The extracted keratin presented a low molar mass of 9 kg mol^-1. Considering the circular economy principles, this work proposes a novel valorization route for feather meal and highlights its potential in creating value-added materials for several applications in medicine, pharmaceuticals, and engineering areas.

Sulfonylurea herbicides are the most widely used herbicides in the world, which are widely used in the prevention and control of weeds in rice, wheat, soybean and other fields. Long-term application will cause environmental pollution, and the use of plasma technology to degrade herbicides in water is expected to be an effective method to restore pollution. In this experiment, corona discharge plasma was used to treat nicosulfuron in water, and the response surface method was used to optimise the operating conditions of the single system of corona discharge treatment of nicosulfuron and the synergistic system of corona discharge treatment of nicosulfuron with the addition of persulfate. The results showed that the degradation rate of nicosulfuron was 75.08% after 10 min under the optimum operating condition of single system. Under the optimum operating conditions, the degradation rate of nicosulfuron after 10 min was 100%. The R² and P values of the two system models were both greater than 9.3 and less than 0.01, and the reliability of the simulated degradation rate data was verified by experiments, which provided basic data for the future research on the use of low temperature plasma to degrade herbicides.

In this paper, a wind tunnel experiment was carried out to study the atmospheric flow and pollutant diffusion around a super-large natural ventilation cooling tower of a nuclear power plant. Considering the effect of the natural ventilation of the cooling tower, with the chimney as the center, X-type hot-wire probes were used to measure the average flow field and turbulence structure of the atmosphere around the cooling tower and other complexes, and pollutant diffusion studies were carried out by tracer experiments. The results show that the super-large natural ventilation cooling tower and its thermal plume emission have a significant effect on pollutant flow and diffusion, changing the trajectory of the plume. When the chimney is located upwind of the cooling tower, some pollutants are emitted secondly due to the entrainment effect through the cooling tower when the plume passes through the natural ventilation cooling tower, regardless of whether or not the cooling tower is operating. Compared with the cooling tower that does not operate, the thermal plume and natural ventilation effects generated by the cooling tower during operation cause the plume dispersion range to widen, the maximum concentration to decrease, and the impact on vertical diffusion to be more significant than that on horizontal diffusion.

Benzo(a)pyrene (BaP) is a well-known environmental contaminant that poses significant risks due to its carcinogenic nature and it is crucial to remove it from the environment, especially in wastewater. Thus, this study aims to enhance the degradation of BaP in wastewater through the optimised interaction of the fungus Aspergillus brasiliensis and the bacterium Sphingomonas spiritovorum. The ideal initial pH and temperature ranges for optimising BaP breakdown were determined using response surface methodology (RSM). For that, the range of initial pH chosen was pH 4-9 and the temperature was between 25℃ - 40℃. The first-order kinetic was used to determine the kinetic response for monoculture and co-culture. The co-culture of A. brasiliensis and S. spiritovorum successfully produced a BaP removal rate of over 50%, which was much higher than the removal rates observed in monoculture treatments under optimisation conditions. The kinetic response was obtained with 0.067 d^-1 (A. brasiliensis), 0.127 d^-1 (S.spriritovorum) and 0.144 d^-1 (co-culture) for the degradation rate constant, K. The degradation half-life time, t_1/2 shows the decrement for the co-culture (4.83 days) compared to monoculture. The increased degradation has been attributed to the synergistic biochemical pathways, in which fungal ligninolytic enzymes initiate the breakdown of BaP, followed by bacterial degradation of the resulting compounds. The study's results, which have been validated by Analysis of Variance (ANOVA), offer insightful information for the enhancement of bioremediation strategies. This information is practicable for researchers, practitioners, and policymakers in the context of addressing carcinogenic pollutants in wastewater.

In this study, the performance of dual-chamber microbial fuel cells with carbon fiber (CF) anodes surface modified by multi-walled carbon nanotube coating (CF-MWCNT) and nitric acid treatment (CF-HNO₃) was compared. The performance of all these modified anodes was found to be better than bare electrode. The modified anodes were shown to significantly outperform the bare electrode anodes. CF-MWCNT and CF-HNO₃ modification increased the maximum power density by 1.60 and 2.88 times to 107 and 193 mw/m², respectively, compared to the bare electrode anode (67 mW/m²). Due to the effect of the modifications, biofilm formation became more denser and stable, the biodegradation rate of organic matter increased and more efficient electron transfer was achieved on the anode surface. These results present effective and simple methods to enhance power generation with carbon fiber electrodes and also suggest ideas that can further improve the performance of modified carbon fiber electrodes. The content of algal biomass obtained in the cathode chamber was analyzed and the highest biomass with 0.71 g/L was obtained in the cell with CF-HNO₃ anode. Carbohydrate, protein and lipid contents were found to be 55%, 15.4% and 24%, respectively. In conclusion, this study demonstrates that surface modifications of carbon fiber anodes are an effective method to enhance the power generation performance of microbial fuel cells and reveals that this approach offers a viable strategy to improve energy efficiency.

Thermal treatment and thermal plasma treatment processes of dairy sludge were conducted. The thermal treatment was undertaken at temperatures from 200 °C to 1000 °C to establish the chemical composition and thermal degradation of the sludge. These results served as a foundation for interpreting the properties of the vitreous slag obtained from the sludge treated in the DC-transferred arc plasma reactor. The dairy sludge is characterised by a high volatile matter but also presents substantial ash content, with primary elements such as Al, P, Si, Ca, and Fe. The characterisations of the samples were made employing techniques like X-ray fluorescence, X-ray diffraction analysis (XRD), FT-IR spectrometry, Thermogravimetric analysis, and Differential Scanning Calorimetry. The results highlight the degradation of primary milk components like lactose, casein protein, and milk fat, with distinct differential thermogravimetric peaks at 230, 316, and 479 °C. As the temperature of thermal treatments approached 1000°C, silicon dioxide, calcium silicon, dicalcium silicate, and hydroxyapatite were identified in XRD spectra. Plasma-treated sludge features various oxide crystalline structures, including Al₂O₃, CaO(Al₂O₃)₆, CaO(Al₂O₃)₂, Ca₂Al(AlSi)O₇, KFeO₂, and ZrO_1.98. FTIR analysis of sludge identifies a complex organic composition presenting alkanes, amines, amides, hydroxyl groups, and metallic and semi-metallic oxide bond absorption. The FTIR results suggest the degradation of organic compounds and retention of phosphorous and aluminum bonds, especially after 600 °C. The vitreous slag from plasma treatment exhibits distinct composition characteristics without organic compound, presenting a vitreous and metallic/ceramic matrix. This research underscores the potential of thermal plasma treatments to neutralise dairy sludge.

The enhanced bioretention system provides a new way to solve the problems of stormwater management brought by urbanization. The knowledge on effects of media modification and long-term operation is scattered, so clogging interaction function, clogging time and depth are analysed to uncover the underneath. River sand, loess, and compost were used as basic fillers, and air-dried water treatment residual (WTR) and recycled aggregate from construction waste (RACW) were used as modifiers to formulate mixed fillers, and synchronized observation of the change rule of hydraulic conductivity and porosity of vertical layering. The study found that the infiltration coefficient of each system tended to decay gradually from top to bottom as the influent TSS accumulated. A set of improved media clogging process prediction framework has been proposed, using rainfall conditions in Northwest China as input conditions, the system clogging time is about 5.5∼7.1 years and the depth of replacement is about 35 cm based on the principles of cake filtration and deep filtration. The results can further understand the function variation of bioretention system under TSS impact conditions, which is helpful to the prediction of the operating life of the system and the evaluation of media replacement depth.

In this study, the start-up and microbial domestication of a salt-tolerant functional anammox system was investigated by gradually increasing the salinity level in a stabilized anammox system in the laboratory. After 44 days of stable operation, the salt-tolerant system was successfully activated, at which time the salinity of the influent water was 3 g/L, and the maximum removal efficiency of ammonia nitrogen and nitrite nitrogen in the system reached 94.18% and 96.66%, respectively, and then the ammonia nitrogen and nitrite nitrogen removal efficiency were stabilized at 88.17% and 96.48% after the enrichment domestication for 89 days. The system was operated in the salinity of 10 g/L, with the concentration of each nitrogen compound measured at the same time. The ammonia nitrogen removal efficiency decreased to 59.93% at a salinity of 10 g/L, which had a significant impact on the system. High-throughput sequencing revealed that the system was enriched with a large number of Chloroflexi, the relative abundance of which increased from 19.46% to 52.33%, and the genus of AnAOB was transformed from Candidatus Brocadia to Candidatus Kuenenia, Candidatus Kuenenia, with a percentage of 4.78%. The system successfully achieved the simultaneous removal of ammonia nitrogen and nitrite nitrogen under salinity stress, which to a certain extent indicated that AnAOB could achieve the initiation and enrichment domestication under salinity conditions, and could provide a basis for the efficient and low-consumption treatment of high salinity nitrogen-containing wastewater.