The primary goal of this work is to develop a technology that allows for the recovery of metal values from waste products, thereby promoting the wise and efficient use of our nation's resources. To achieve this goal, an industrial waste of El Kriymat boiler fly Ash was used for recovering its content of vanadium, nickel and zinc. About 97, 95 and 99% respectively of these economic elements were first dissolved from boiler fly ash magnetic concentrate (after physical concentration). Leaching experiments using optimum conditions include: 180 g/L sulfuric acid concentration and 4% solid/solid proportion manganese dioxide acts as an oxidant at 80 °C. The recovery of vanadium (V) metal ions was carried out using 3% Alamine 336 in kerosene at an equilibrium pH value of 0.9. Subsequently, 15% sodium sulfide solution was used for co-precipitation of nickel and zinc metal ions in the raffinate solution at pH value of 3.5.
There is a growing need to find ways to reuse fine concrete waste from the construction industry. In this study, recycled concrete fines were granulated and used as lightweight aggregates. Ladle slag, a steel industry residue, was used as a co-binder in different ratios (0, 10, 20, and 30%). The materials were blended and granulated, and then the granules were cured in three conditions: ambient condition, humidity chamber, and carbonation chamber. The results showed that the ladle slag content of 30% cured in a humidity chamber produced the strongest granules, with a crushing strength of 127 N, which was 135% greater than a commercial lightweight aggregate. The granules generally had satisfactory density and water absorption with a higher ladle slag content. Carbonation increased the granule strength with a low ladle slag content and decreased the granules’ water absorption. The improved physical and mechanical properties of carbonated granules are attributed to the formation of calcium carbonate during the carbonation process. The granules produced in this study show good potential for use as lightweight aggregates in the construction industry.
This work was focused on evaluating the suitability of replacing Portland cement (PC) by 5, 10 and 15 mass % of activated alum sludge waste (AAS) as a pozzolanic material. Exploitation of low-cost nanocomposite for bolstering the physical, mechanical, and stability against firing of PC–AAS-hardened composites was inspected. CuFe2O4 spinel nanoparticle with average particle size (~ 50 nm) was prepared. Inclusion of CuFe2O4 spinel in different PC–AAS-hardened composites bolsters their physicomechanical features at almost normal curing ages as well as their stability against firing. The positive impact of synthesized CuFe2O4 spinel was affirmed via TGA/DTG and XRD techniques, which indicated the presence of diverse hydration yields such as CSHs, CASHs, CFSH, and CuSH that enhance the overall physicomechanical characteristics and thermal stability of various PC–AAS-hardened composites. The composite containing (90 PC–10 AAS waste–2 CuFe2O4) offers many benefits from the economic and environmental view.
Material flow analysis (MFA) is an effective tool for waste management, but low- and middle-income countries lack essential data for MFA. This study proposed a simplified MFA (sMFA) utilizing local expert judgment (LEJ) and examining the impact of simplification on its uncertainty. A stochastic sMFA model was developed for nitrogen and phosphorus in urban Mandalay, Myanmar. This model was compared with the intensive MFA (iMFA) model employing intensive surveys for primary data collection. For the total loadings to the environment, the medians of the sMFA were higher by 3% and 11%, respectively, for nitrogen and phosphorus than those of the iMFA. The widths of the 80% confidence intervals of these loadings in the sMFA, normalized by those in the iMFA, were − 0.05 and − 0.11, respectively. The three largest flows to the environment were the same for the two models: on-site sanitation effluent/leakage, greywater, and industrial wastewater. Large median gaps between the models were observed for industrial wastewater, fecal sludge, and human excreta, associated with informal waste management, whereby LEJ did not work well. Overall, the sMFA demonstrated a good estimation of nitrogen and phosphorus flows with limited increase of uncertainty, still requiring focused attention on informal waste streams.
Hydrogels are a kind of three dimensional polymeric network system which has a significant amount of water imbibing capacity despite being soluble in it. Because of the potential applications of hydrogels in different fields such as biomedical, pharmaceutical, personal care products, biosensors, and cosmetics, it has become a very popular area of research in recent decades. Hydrogels, prepared from synthetic polymers and petrochemicals are not ecofriendly. For preparing biodegradable hydrogels, most available plant polysaccharides like starch are utilized. In its structure, starch has a large number of hydroxyl groups that aid in hydrogel networking. For their easy availability and applications, starch-based hydrogels (SHs) have gained huge attention. Moreover, SHs are non-toxic, biocompatible, and cheap. For these reasons, SHs can be an alternative to synthetic hydrogels. The main focus of this review is to provide a comprehensive summary of the structure and characteristics of starch, preparation, and characterization of SHs. This review also addresses several potential multidimensional applications of SHs and shows some future aspects in accordance.
Recently, nanosized cellulose materials extraction is extensively interesting from the sources of sustainable materials. Cellulose nanofibrils (CNF) extraction through green bio-based materials featured as promising interest in the field of science. In this study, dimethyl sulfoxide (DMSO) was applied to examine its effectiveness in pretreating the Ficus natalensis barkcloth cellulose (FNBC) for CNF production before 2,2,6,6,-tetramethylpiperidine-1-oxyl (TEMPO) oxidation. The pretreatment performance of DMSO was evaluated based on the structural and morphological changes. DMSO pretreated FNBC attained the most dramatic morphological changes as compared to untreated cellulose samples. The results of the scanning electron microscope (SEM) and transmission electron microscope (TEM) shows that there is an extensive structural disruption of FNBC during the pretreatment process, which could be because of outstanding ability to eliminate non-cellulosic materials and amorphous regions from the FNBC, confirmed by the X-ray diffractometry (XRD) showing higher crystallinity values, as well as higher thermal stabilities values of pretreated FNBC samples, were also noted. Overall, this study revealed a tremendously effective and pioneer pretreatment method for fractionating FNBC, to stimulate the successive extraction of cellulose nanofibrils. Furthermore, based on the cellulose and CNF characterizations, this study showed that F. natalensis barkcloth could be considered as an alternative source of cellulose for potential value-added industrial applications such as the food industry, paper making, and biomedicines.
The substance class of inert organic-chemical stressors (IOCS) describes organic-chemical (macro-) molecules, which demonstrate a high level of persistence upon entry in the ecosystem, and whose degradation is limited. These synthetically produced organic-chemical macromolecules, which are often derived from the polymerization of different monomers, are, in the form of plastics, indispensable in the everyday world. They enter the environmental compartments and cause great damage due to primary (industry, cosmetic, washing of textile), and secondary (degradation) entry. If these particles get into aquatic systems, this has fatal consequences for the ecosystem such as the death of marine animals, or bioaccumulation. Wastewater treatment plants are reaching their limits and require innovative ideas for the sustainable removal of microplastic. This article examines a new approach to the removal of polymers from aquatic systems (lab scale) by using sol–gel induced agglomeration reactions to form larger particle agglomerates. These enlarged agglomerates can be separated much more easily from the wastewater, since they float on the water surface. Separation systems, e.g. sand trap can easily be used. A further advantage is that the agglomeration can be carried out completely independently of the type, size, and amount of the trace substance concentration as well as of the external influences (pH value, temperature, pressure). Thus, this new type of particle separation can not only be used in sewage treatment plants, but can also be transferred to decentralized systems (e.g. implementation in industrial processes).
A dynamic model of the carbon budget of an oak forest ecosystem that takes into account forest stand age was developed. A
numerical experiment was designed to simulate the afforestation process, and a Monte Carlo simulation was performed to determine
how parameter uncertainties and environmental variability influence the result. It was found that while the total amount of
carbon stored in the ecosystem increases from 1.9 kg C/m2 to 4.4 kg C/m2 over the following 20 years, the relative standard deviation increases from 9 to 21%. The contribution of varying climate
and carbon dioxide parameters to total uncertainty is substantial; for example, the standard deviation at the 10th modeling
year for phytomass doubles and the uncertainties of the soil pool and total accumulated carbon increase by a factor of nearly
1.4, while the uncertainty of the litter pool stays almost at the same level. 相似文献
Estimates of the global carbon sink induced by nitrogen enrichment range vary widely, from nearly zero to 2.3 Gt C year-1. It is necessary to reduce this uncertainty if we are to make accurate predictions of the future magnitude of the terrestrial carbon sink. Here, we present a Monte Carlo approach to uncertainty and sensitivity analysis of three ecosystem models, Century,BGCand Hybrid. These models were applied to a coniferous forest ecosystem in Sweden. The best estimate of the change in total carbon content of the ecosystem with the cumulative change in nitrogen deposition over 100 years, Ctotal/Ndeposition was 20.1 kg C (kg N)-1 using the pooled mean, with a pooled standard deviation of 13.8 kg C (kg N)-1. Variability in parameters accounted for 92% of the total uncertainty in Ctotal/Ndeposition, and only 8% was attributable to differences between models. The most sensitive parameters were those which controlled the allocation of assimilate between leaves, roots and stem. In particular, an increase in allocation to fine roots led to a large reduction in Ctotal/Ndeposition in all models, because the fine roots have a very high turnover rate, and extra carbon allocated there is soon lost through mortality and decomposition. 相似文献
Estimates of the global carbon sink induced by nitrogen enrichment range vary widely, from nearly zero to 2.3 Gt C year?1. It is necessary to reduce this uncertainty if we are to make accurate predictions of the future magnitude of the terrestrial carbon sink. Here, we present a Monte Carlo approach to uncertainty and sensitivity analysis of three ecosystem models, Century, BGC and Hybrid. These models were applied to a coniferous forest ecosystem in Sweden. The best estimate of the change in total carbon content of the ecosystem with the cumulative change in nitrogen deposition over 100 years, ΔCtotal/ΔNdeposition was 20.1 kg C (kg N)?1 using the pooled mean, with a pooled standard deviation of 13.8 kg C (kg N)?1. Variability in parameters accounted for 92% of the total uncertainty in ΔCtotal/ΔNdeposition, and only 8% was attributable to differences between models. The most sensitive parameters were those which controlled the allocation of assimilate between leaves, roots and stem. In particular, an increase in allocation to fine roots led to a large reduction in ΔCtotal/ΔNdeposition in all models, because the fine roots have a very high turnover rate, and extra carbon allocated there is soon lost through mortality and decomposition. 相似文献
Composting is a good method for recycling surplus manure and stabilizing organic matter from biowastes. Compost is used as a soil amendment and recently, for restoration of vegetation in barren areas. We investigated the relationship between the type of woody biomass (using Robinia pseudoacacia, Japanese larch and apple) and the humification index (HI) of the resulting compost. This study evaluated the difference in HI between the three compost types, and the structural features of composts and extracted humic acids (HAs). The HIs for R. pseudoacacia and apple were larger than that for Japanese larch after composting for 11 months. The structural features of the Japanese larch compost were also different from the apple and R. pseudoacacia, with a very high carbon/nitrogen ratio. The average molecular weights and ultraviolet–visible spectra (A600/C) of HAs extracted from composting samples at 0 and 11 months indicate that the humification rate of Japanese larch was slower than that of R. pseudoacacia and apple. During composting, the average molecular weights of apple and R. pseudoacacia decreased, while their A600/C values increased, but the reverse was observed for Japanese larch. The humification rate was found to depend on the type of woody biomass being composted. 相似文献
In this study, we have used the MAGIC model together with data from the Birkenes catchment in Norway, at which 27 years of data (1974–2000) are available. We calibrated the MAGIC model to the five year observed average chemistry around 1990, and then used the data from the five year period around 1980 to refine the calibration. From 1990, forecasts were run for the different sets of inputs and parameters, and the sets of inputs and parameters were further refined using observations for the period 1996–2000. Through an automatic calibration routine, the model was calibrated a large number of times with different sets of input data to account for the uncertainties in the observed data using a Monte Carlo set-up. The results show that the uncertainty in the model predictions decreases as more observed data from different points in time are used in the model calibration. The results also show that when usingthe time series data in calibration, the distribution of the forecastchanged. The distribution of the predicted Acid Neutralisation Capacity (ANC) in the future is lower for the more refined model calibration. The 10 and 90 percentiles of predicted ANC in 2010 are –3 to 21 μeq L-1 when only a five-year average is used for calibration, but are –7 to 9 μeq L-1 when data from the three different time periods are used. 相似文献
Aerosol particles in the workplace of a detergent industry were sampled during July 2005 by a Berner low-pressure impactor.
The samples were analyzed by atomic absorption spectrometry and ion chromatography in order to determine the size distribution
of metallic elements and water-soluble inorganic ions. The size distributions of some characteristic metallic elements (Cu,
Fe, Al) were unimodal with their maximum found in coarse particles. Among the water-soluble aerosol components , , Cl−, and Ca++ were the major contributors to total particle mass. The lung deposition resulting from the partially hygroscopic aerosol
is estimated. The calculated lung deposition reveals the impact of separate chemical aerosol compounds on the levels of the
inhaled dose. The differences observed between the total and regional deposition of the different compounds appear mainly
due to their different size distributions.
An erratum to this article can be found at 相似文献
Swine manure was subjected to laboratory scale composting in order to quantify bioaerosols, i.e., airborne culturable bacteria and endotoxin, in the exhaust gas, which provided details on the effect of temperature on bacterial emissions. The concentration of airborne bacteria reached 31,250 colony-forming units (CFU)/m3 during the thermophilic stage of composting, and positively correlated with the temperature profile of the compost pile. Initially, the endotoxin concentration was 1820 endotoxin units (EU)/m3, but it decreased exponentially as the composting process proceeded. The temperature can be an excellent indicator of bacterial emissions during the composting process, indicating that the composting process requires a consistently high temperature to ensure sanitization of both compost and bacterial emissions. The cumulative emission data showed that emission factors was 11.2?13.5 CFU/g dry swine manure and that of endotoxin was 0.5?0.9 EU/g dry swine manure. The bacterial diversity in the bioaerosol was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis, revealing the presence of various gram-negative bacterial consortia. 相似文献
Anaerobic digestion is a waste treatment method which is of increasing interest worldwide. At the end of the process, a digestate remains, which can gain added value by being composted. A study was conducted in order to investigate microbial community dynamics during the composting process of a mixture of anaerobic digestate (derived from the anaerobic digestion of municipal food waste), green wastes and a screened compost (green waste/kitchen waste compost), using the COMPOCHIP microarray. The composting process showed a typical temperature development, and the highest degradation rates occurred during the first 14 days of composting, as seen from the elevated CO2 content in the exhaust air. With an exception of elevated nitrite and nitrate levels in the day 34 samples, physical–chemical parameters for all compost samples collected during the 63 day process indicated typical composting conditions. The microbial communities changed over the 63 days of composting. According to principal component analysis of the COMPOCHIP microarray results, compost samples from the start of the experiment were found to cluster most closely with the digestate and screened compost samples. The green waste samples were found to group separately. All starting materials investigated were found to yield fewer and lower signals when compared to the samples collected during the composting experiment. 相似文献
Three cruises were carried out in Jiaozhou Bay (JZB) in the neap tide in October 2002 (fall) and in both neap and spring tides
in May 2003 (spring) to understand the relative importance of external nutrient inputs versus physical transport and internal
biogeochemical processes. Nutrients (, , , , silicic acid, total dissolved nitrogen (TDN) and phosphorus (TDP), dissolved organic nitrogen (DON) and phosphorus (DOP))
were measured. The concentrations of nutrients were higher in the northern part than in the southern part. High concentrations
of and DON in JZB demonstrated the anthropogenic input. Ambient nutrient ratios indicated that the potential limiting nutrients
for phytoplankton growth were silicon, and then phosphorus. Nutrients showed an obvious tidal effect with low values at flood
tide and high values at ebb tide. Nutrient elements were transported into JZB in the north and output in the south (i.e.,
into the Yellow Sea), which varied with season, tidal cycle and investigation sites. Water exchange between JZB and the Yellow
Sea exports , and DON out of JZB, while it inputs , silicic acid and DOP into JZB. Nutrient budgets demonstrate that riverine input and wastewater discharge are major sources
of nutrients, while residual flow is of minor importance in JZB ecosystem. JZB is a sink for the nutrient elements we studied
except for DON. Stoichiometric calculations demonstrate that JZB is a net autotrophic system. 相似文献
Steady-state models for the prediction of P retention coefficient (R) in lakes were evaluated using data from 93 natural lakes and 119 reservoirs situated in the temperate zone. Most of the
already existing models predicted R relatively successfully in lakes while it was seriously under-estimated in reservoirs. A statistical analysis indicated the
main causes of differences in R between lakes and reservoirs: (a) distinct relationships between P sedimentation coefficient, depth, and water residence
time; (b) existence of significant inflow–outflow P concentration gradients in reservoirs. Two new models of different complexity
were developed for estimating R in reservoirs: , where τ is water residence time (year), was derived from the Vollenweider/Larsen and Mercier model by adding a calibrated parameter
accounting for spatial P non-homogeneity in the water body, and is applicable for reservoirs but not lakes, and , where [Pin] is volume-weighted P concentration in all inputs to the water body (μg l−1), was obtained by re-calibrating the OECD general equation, and is generally applicable for both lakes and reservoirs. These
optimised models yield unbiased estimates over a large range of reservoir types.相似文献
