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Versatility of iron-rich steel waste for the removal of high arsenic and sulfate concentrations in water Texte intégral
2019
Araujo, Sandrine F. | Caldeira, Cláudia L. | Ciminelli, V. S. T. | Silva, Ariadna | Amorim, Camila C.
The aim of this work is to evaluate the application of a steel waste, basic oxygen furnace sludge (BOFS), rich in iron, to treat water contaminated with elevated arsenic and sulfate concentrations. In the first step, three doses (10, 60, and 80 g L⁻¹) of BOFS were tested to investigate the removal of As(III) and As(V) (67 mg L⁻¹) and sulfate (3700 mg L⁻¹) separately from an aqueous solution. In the second step, the efficacies of BOFS (10 g L⁻¹) and commercial ZVI (5 g L⁻¹) were compared to simultaneously remove arsenic and sulfate. The pH of the feed solution was adjusted to 2.5 and monitored during the experiment. The use of BOFS achieved arsenic removal up to 92% and sulfate removal of nearly 40% after 72 h of contact time. Use of BOFS also increased the solution pH to 12. Similar removal levels were achieved with both BOFS and ZVI. These results confirm the potential application of BOFS to remove high arsenic and sulfate concentrations from acidic solutions. The data obtained here should be used as a basis for further studies on the remediation of acid mine drainage with high concentrations of arsenic and sulfate using an abundant and low-cost steel waste.
Afficher plus [+] Moins [-]Analysis of Influencing Factors on Sustainability of Textile Wastewater: a Structural Equation Approach Texte intégral
2019
Pattnaik, Punyasloka | Dangayach, G. S.
The purpose of this study was the identification of the major factor for sustainable development in textile industries and preferred textile wastewater management practices for environmental protection. Moreover, a structural framework for sustainable textile wastewater management concept in the textile industry was developed, and further, the proposed model was examined based on the effect of economic performance, environmental impact, and operational performance in textile sectors. Therefore, to achieve the above issues, major factors were identified through exhaustive literature, and then a test was conducted for the reliability of the proposed constructs for validation. However, there was no specific study on the sustainability of textile wastewater management principle by using exploratory structural equation modeling (SEM). Finally, the proposed structural model was validated by confirmatory factor analysis (CFA) and structural equation modeling with the help of the SPSS software package.
Afficher plus [+] Moins [-]From Saprotrophic to Clear Water Status: the Restoration Path of a Degraded Urban Lake Texte intégral
2019
Grochowska, Jolanta | Augustyniak, Renata | Łopata, Michał | Parszuto, Katarzyna | Tandyrak, Renata | Płachta, Anna
The study was conducted on Długie Lake in Olsztyn, which for 20 years since the mid-1950s served as a domestic and storm wastewater receiver, which led to its complete degradation. The discontinuation of wastewater inflow in 1976 caused a change in the trophic state from saprotrophic to hypertrophic. Evident improvement of water quality was possible only after the implementation of proper restoration techniques. Długie Lake was subjected to artificial aeration with thermal destratification (1987–2000). After all opportunities to improve water quality in the lake by artificial aeration (low phosphorus sorption capacity of sediment) had been exhausted, it was decided that a phosphorus inactivation method using the coagulant PAX 18 be used (2001–2003). Before restoration, the nutrient concentration in the near-bottom water layer of Długie Lake was very high at 22.9 mg TN L⁻¹ and 3.50 mg TP L⁻¹. The average amount of chlorophyll a was ca. 200 μg L⁻¹, and the Secchi disc visibility did not exceed 1 m. In 2017, 14 years after termination of the lake restoration process, the total phosphorus concentration at the bottom was 0.21 mg P L⁻¹ on average, and the total nitrogen was 1.5 mg N L⁻¹. The mean transparency of the water oscillated around approximately 5 m, and the amount of chlorophyll a was 1.86 μg L⁻¹. Studies have shown that the most important step in reclamation is to prevent pollutants from entering the lake to the maximum extent possible and to use a combination of several reclamation methods as a matter of good practice. Stable environmental conditions have developed in the lake, and the values of chlorophyll a and the Secchi disk visibility indicate that the lake has reached a mesotrophic state.
Afficher plus [+] Moins [-]Coal seam water infusion for dust control: a technical review Texte intégral
2019
Zhang, Kaixuan | Zhang, Jian | Wei, Jianping | Ren, Ting | Xu, Xiangyu
Coal mine dust continues to be a health and safety issue in underground coal mines. Coal seam water infusion was developed and widely applied in European coal mines for dust control, and was also a common practice in most Chinese coal mines. This method typically involves the infusion of water into the coal seam to increase its moisture content, and therefore reduce dust generation during mining operations. With the availability of other dust control methods such as water spraying systems, the water infusion method has not been considered as a viable means for dust mitigation in modern mines. However, the increase in production output and the deployment of more powerful equipment for coal cutting and transport and intensive gas drainage practices mean that workers could be exposed to more dust contaminations. Whilst the mine operators are committed to suppress and dilute airborne dust particles using these passive measures, there is a need to critically examine and subsequently develop this proactive dust control technology for practical applications in Chinese coal mines. The paper provides a critical review of the water infusion technologies in view of its technological advances and practical application limitations. The methods of water infusion, mechanism of water flow in coal, the role of surfactants and the key parameters influencing the effect of water infusion on dust control are identified and discussed. Existing problems and prospects for water infusion are analysed.
Afficher plus [+] Moins [-]Ultrathin Support-Free Membrane with High Water Flux for Forward Osmosis Desalination Texte intégral
2019
Zheng, Meiyu | Zhao, Xiaoyu | Xu, Shu | Lu, Dongwei
In this work, an ultrathin polyamide (PA) membrane was fabricated via in situ removing polysulfone (PSF) substrate from the PSF-PA forward osmosis membrane for the first time. The physicochemical properties of the PA membranes were confirmed by means of surface morphology, chemistry analysis, and surface charge characterization. The performance of PA, PSF-PA, and physically combined PSF+PA membrane was compared in terms of water flux, reverse salt flux, and selectivity. The flux performance of these three membranes followed the order of PA>PSF-PA>PSF+PA membranes, and the possible mechanism for their performance was proposed. Compared with home-made PSF-PA and PSF+PA membranes, the ultrathin PA membrane had high water flux (i.e., 80.54 LMH) due to its low membrane resistance and minimized internal concentration polarization under same operation conditions (i.e., DI water feed solution, 1.0 M NaCl draw solution, and AL-FS orientation). This study would provide insights on the preparation and application of ultrathin PA membranes with high permeability in the context of global water/energy-related crisis.
Afficher plus [+] Moins [-]Electrolytic Recovery of Nickel and Copper from Acid Pickling Solutions Used to Treat Metal Surfaces Texte intégral
2019
Collivignarelli, Maria Cristina | Abbà, Alessandro | Bestetti, Massimiliano | Crotti, Barbara Marianna | Carnevale Miino, Marco
The increased use of heavy metals in process industries often results in the generation of large quantities of wastewater (WW) and aqueous waste (AW) containing mixtures of heavy metals such as copper and nickel. This research focuses on the electrochemical recovery of copper and nickel from acid pickling solutions used to treat metal surfaces. Using hull cells, beaker plating, and electrolytic cells in pilot scale (capacity 30 L), the most important parameters influencing the process have been identified (temperature, contact time, and current density). In total, about 60 tests were carried out on AW containing nickel and copper. The results of the tests carried out with copper-containing AW shows that removal yields are often higher than 50%; while the energy consumption is less than 15 kWh kg⁻¹ of metal deposited. The best removal efficiency (100%) was achieved by applying a current density of 6 A dm⁻² and the energy consumption was 2 kWh kg⁻¹. The tests carried out with AW containing nickel point out very low removal yields (< 20%) and very high energy consumption (even exceeding 300 kWh kg⁻¹). The best removal yield obtained, applying a current density of 3 A dm⁻², is 6.7% with an energy consumption of 40 kWh kg⁻¹ of metal removed. A costs analysis based on Metal Exchange value was carried out. The cost analysis suggests that the results, in terms of removal and recovery, obtained for these metals, in particular for copper, are very promising for an industrial application.
Afficher plus [+] Moins [-]Increasingly Distant from Eden—a Look at the Soils of Protected Areas Using Ecotoxicological Tests and Chemical Analysis Texte intégral
2019
Honscha, Laiz Coutelle | de Moura, Renata Rodrigues | Baisch, Paulo Roberto Martins | Da Silva Júnior, Flavio Manoel Rodrigues
On the basis of the assumption that legally protected areas are created to maintain environmental quality that, in turn, is indispensable for quality of life, this study aims to evaluate the soil conditions in protected areas that are located near urban regions by using ecotoxicological assays and chemical analysis. The study was carried out using surface soil samples collected from seven protected areas in southern Brazil. For the protected area to be considered “clean,” the results of the ecotoxicological tests should be within the criteria accepted for negative control according to standardized protocols, and the concentration of chemical elements should be below the maximum levels allowed by Brazilian law. On the basis of the criteria adopted for ecotoxicological assays and chemical analysis, soil from only two of the seven protected areas (28.6%) met the criteria for being considered “clean.” This probably reflects the influence of anthropogenic activities within the protected areas, demonstrating drawbacks of delimitation and management. The strategy used in this study could be used to assess the anthropogenic impact on protected areas in other parts of the world.
Afficher plus [+] Moins [-]Amendment of Caulerpa sertularioides marine alga with sulfur-containing materials to accelerate Cu removal from aqueous media Texte intégral
2019
Ramavandi, Bahman | Dobaradaran, Sina | Papari, Fatemeh | Sorial, George A. | Ebrahimi, Ahmad | Khaksar, Leila Madeh | Akbarzadeh, Samad | Hashemi, Seyedenayat | Teimori, Fatemeh
This study reports a new approach of alga amendment in a live mode. The Caulerpa sertularioides alga was modified with sulfur-containing materials of methionine (C₅H₁₁NO₂S) and sodium sulfate (Na₂SO₄) to more concentrate the sulfur content of the yielded biomass (adsorbent). The simple and amended C. sertularioides alga was fully characterized with FTIR, SEM, EDX, BET, BJH, and pHzₚc techniques. The copper adsorption from aqueous media was done by three adsorbents of C. sertularioides-simple (CSS), C. sertularioides-Na₂SO₄ (CSN), and C. sertularioides-C₅H₁₁NO₂S (CSC). The parameters of pH (2–6), adsorbent dosage (2–10 g/L), and contact time (3–80 min) were optimized at 5, 5 g/L, and 60 min, respectively. According to Langmuir isotherm (the best-fitted model), the maximum adsorption capacity of CSN (98.04 mg/g) was obtained 2.4 times higher than CSC (40.73 mg/g) and 9.5 times higher than CSS (10.29 mg/g). The Cu adsorption process by the adsorbents was best-fitted pseudo-second-order kinetic model. The CSN, CSC, and CSS biomasses were successfully reused 5, 4, and 4 times, respectively. The thermodynamic study revealed that the copper adsorption process by CSN is exothermic and non-spontaneous. Finally, the suitability of adsorbents prepared from algae was tested by cleaning a simulated wastewater.
Afficher plus [+] Moins [-]Occurrences and patterns of residual organochlorine pesticides (OCPs) in cultured Chinese mitten crab (Eriocheir sinensis) in China: concentrations, sources, and a human health risk assessment Texte intégral
2019
Song, Chao | Zhang, Cong | Zhang, Jingwei | Zhang, Xiaowei
Seventy Chinese mitten crab samples, encompassing a total of 2100 individuals, were collected from the main production areas in China. The objective was to assess the occurrences and patterns of 23 selected organochlorine pesticides (OCPs) in the edible tissues and assess the associated dietary risk. Concentrations of total residual OCPs in the mitten crabs ranged from 0.72 to 51.51 μg kg⁻¹, which was comparable to other global aquatic species. Dichlorodiphenyl trichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) were the two main contributors of total OCPs, with the detected values ranging from 0.14 to 30.89 μg kg⁻¹ and 0.23 to 4.04 μg kg⁻¹, respectively. Source analysis indicated the coexistence of both residual and recent DDT inputs, while there was no indication of HCH usage in the main production area of mitten crab. In terms of dietary risk, at least eight individual mitten crabs per day are permissible for consumption by local residents, indicating low risk from consumption. The results presented herein should guide the production and consumption of mitten crab, as well as promote the sustainable development of aquaculture in China.
Afficher plus [+] Moins [-]Analyses of Influencing Factors for Radon Emanation and Exhalation in Soil Texte intégral
2019
Zhang, Wei Qiang | Zhang, Yuliang | Sun, Qiang
The study on radon emanation and exhalation in soil is more and more important for environmental protection, and many influencing factors on radon emanation coefficient and exhalation in soil have been well documented. In order to evaluate the radon change and key influencing factors, this paper made an overall summary based on these studies. The main results show that the change laws of emanation coefficient with elevated temperature of radon can be divided into three types and they relate to the moisture state and content of soil. The normalized radon exhalation has a negative linear correlation with temperature, and the maximum emanation coefficient has a positive linear correlation with heating rate and specific surface. The pores with different size have different effects on the emanation coefficient of radon in the soil, e.g., the micro-pores increase emanation coefficient, and the mezzo-pores decrease emanation coefficient. Taken together, our results offered guiding significance for the evaluation of radon in soil and in air when soil state changes. Lastly, the existing problems and research directions were also given.
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