خيارات البحث
النتائج 3161 - 3170 من 6,535
Realistic Decontamination of Fe2+ Ions from Groundwater Using Bentonite/Chitosan Composite Fixed Bed Column Studies
2020
M.E.M. Hassouna and M. H. Mahmoud
Bentonite/chitosan composite was synthesized and characterized by different techniques including XRD, FT-IR, SEM and TEM to detect its physicochemical properties. The composite was introduced in realistic purification application to reduce the dissolved iron content in raw groundwater sample by fixed-bed column system. The plotted breakthrough curves and the related mathematical parameters revealed that the column achieves iron removal percentage of about 69% from 6.6 L of water after adjusting the factors affecting the system at 3 cm bed thickness, 5 mL/min flow rate, 5 mg/L concentration and pH 6. Applying the column system to remove iron from groundwater under the same conditions can achieve iron removal percentage of about 69% from a total volume of 8.2 L of water. The interaction of the metal on the column was attained after 18 hours and the saturation time was attained after 27.5 hours which revealed the high performance of the composite in the designed column system for the purification of groundwater.
اظهر المزيد [+] اقل [-]Adsorption Process of Ammonia Nitrogen in Solution by the Modified Biochar from Corn Straw
2020
Ruolin Xu, Li Han, Chengcai Huang, Hao Zhang, Rui Qin, Linli Zhang and Muqing Qiu
The biochar was prepared by pyrolyzing corn straw at 773 K temperature under an oxygen-limited condition. Then, the gained biochar samples were further modified with MgCl2 solution through mixing method for 3 h at the speed of 120 rpm. The physicochemical properties of the modified biochar from corn straw were investigated by surface area analysis, elemental analysis, scanning electron microscope, X-ray diffraction and Fourier transform infrared spectroscopy spectra. The adsorption experiments of ammonia nitrogen in aqueous solution by modified biochar were carried out. The results showed that the modified biochar contains high surface area, rough surface and a lot of oxygen-containing functional groups. The adsorption process fits well with the pseudo-second-order kinetics equation and Langmuir isotherm equation. The adsorption mechanism of modified biochar to NH4 + ion in aqueous solution includes ion exchange and physical adsorption. The ion exchange is primary in the process of adsorption.
اظهر المزيد [+] اقل [-]Quality Assessment of Groundwater from the Coal Bearing Aquifer in the Xinji Coalfield, Anhui Province, China
2020
S.B. Feng and L.H. Sun
In this study, a total of 50 groundwater samples from the coal-bearing aquifer in the Xinji coalfield (one sub-coalfield of the Huainan coalfield) have been collected, and their major ion concentrations have been measured for the evaluation of its suitability for drinking and irrigation, and then the mechanism controlling the water chemistry have been analysed. The results indicate that the groundwater samples are slightly alkaline with TDS higher than the freshwater (<1000 mg/L), and most of them are classified to be Cl- and HCO3- types. The groundwater samples have WQI range from 5.63 to 179 (mean = 64.9), suggesting that these samples are good for drinking. However, the results of sodium adsorption ratio and residual sodium carbonate indicate that only a few of the samples can meet the requirement of irrigation, but must be treated before application. Gibbs diagram and the relationships between major ions, as well as the factor analysis, imply that water-rock interaction is the main process controlling the groundwater chemistry, including the dissolution of evaporate minerals and the weathering of silicate minerals.
اظهر المزيد [+] اقل [-]Comparison Study of Various Cellulose Acetylation Methods from its IR Spectra and Morphological Pattern of Cellulose Acetate as a Biomass Valorisation
2020
Roni Maryana, Muslih Anwar, Andri Suwanto, Siti Uswatun Hasanah , Eka Fitriana
Recently substitution of fossil fuel-based polymer by natural polymer sources has been studied. Cellulose acetate that can be produced from the cellulose of biomass waste is an environmentally friendly and important polymer with many applications. This study was undertaken to determine the most suitable and effective method in the cellulose acetate (CA) production. Moreover, the role of catalyst and usefulness of trichloroacetate and I2 catalyst has been studied. As many as 12 methods of acetylation for CA synthesis has been carried out, and the results have been compared. The peak height ratio of infrared (IR) spectra of acetyl groups was studied to determine the formation of CA. The result showed that the activation step resulted in higher IR spectra peak than the direct synthesis method. An important result of this study was shown when trichloroacetate catalyst combined with H2SO4 resulted in significantly higher IR spectra than the conventional method. Interestingly, I2 catalyst resulted in better IR spectra peak than H2SO4 did, even the activation step was not performed. It showed that the addition of trichloroacetate and I2 in the CA synthesis with acetic anhydride as an acetylating agent was better than conventional CA acetylation method. Furthermore, I2 catalyst showed the best result among other methods and will be the promising pathway to produce CA. Scanning electron microscopy (SEM) analysis showed that the diameter of cellulose fibre was decreased and fracture surface occurred after the synthesis reaction.
اظهر المزيد [+] اقل [-]Macroscopic Factors Decomposition of Methane Emissions from Livestock Based on the Empirical Analysis of 31 Provinces in China
2020
Wenjie Yao and Huili Wang
This paper builds a factor decomposition model of methane emissions from livestock from the three dimensions of technology, economy, and population, by using the panel data covering 31 provincial regions in China during 2003-2016, and aims to reveal the macroscopic causes of methane emissions from livestock. The research shows that technical, economic and population factors of methane emissions from livestock have diminishing marginal contribution. The methane emissions from intestinal fermentation are mainly restricted by livestock’s physiological structure. Following increase or decrease of livestock feeding quantity, it changes with a relatively stable parameter and has little controllability. Methane emissions from faecal management are limited little by livestock’s physiological structure and it is largely controllable. The government should increase technical input to reduce methane emission factors of livestock, deal with livestock manure through resource utilization, and reduce raising scale by using a certain market mechanism in due course.
اظهر المزيد [+] اقل [-]Biodegradation of Textile Wastewater by Naturally Attenuated Enterobacter sp.
2020
N. Sharma, H. Bhagwani, N. Yadav , D. Chahar
The exponential increase in anthropogenic activities has led to the accumulation of xenobiotics into the environment, synthetic dyes being one of the culprits. Noteworthy is the fact that the textile industry utilizes enormous volumes of water for dyeing and printing unit operations thereby generating wastewater proportionately. Taking into consideration, implications of toxic textile effluents, a pilot study was planned to screen for naturally attenuated bacterial isolates capable of degrading textile effluents. Requisite effluent samples were collected from Kelki Printers Co-operative Society Limited, Sanganer, Jaipur and bacterial screening was carried out by bioaccumulation of Remazol Brilliant Blue R (RBRR) (formation of halo around colonies). Of the 19 bacterial isolates obtained, the most promiscuous isolate was biochemically characterized as Enterobacter sp. For biodegradative investigations, it was inoculated in sterilized textile effluent and incubated at 37°C for 7 days under agitating conditions. Pre and post bacterial inoculation (1% v/v), Physico-chemical parameters were analysed following standard procedures. A significant (p<0.05) lowering of pollution indicators was monitored when contrasted with abiotic control. The present study was aimed to explore the role of naturally attenuated and effluent adapted Enterobacter sp. screened from untreated textile effluent based on its colour (RBRR) removal efficacy under in vitro conditions. Furthermore, it was also explored for its biodegradative properties to minimize the level of potential pollution indicators through the microcosm approach. This pilot study based on a three-tier approach encompassing bioprospecting, bio enrichment and bioaugmentation plausibly provided insights for enhanced degradation of real dye wastewaters by unlocking the biochemical pathways of adapted microbes.
اظهر المزيد [+] اقل [-]The Kinetic Model for Decolourization of Commercial Direct Blue 2 Azo Dye Aqueous Solution by the Fenton Process and the Effect of Inorganic Salts
2020
Hasan F. Al-Rubai, Ahmed K. Hassan and Bahaa M. Altahir
The study of Fenton’s oxidation and degradation of Direct Blue 2 (DB2) as the commercial azo dye in synthetic aqueous solution has been accomplished. The optimum oxidative degradation reaction conditions were achieved as follows: pH = 3.50, [H2O2] = 1.1×10-3 M, [Fe2+] = 1.0×10-4 M for [DB 2] = 1.0×10-4 M. Under optimal conditions, 80% of decolouration efficiency was carried out within 15 min of reaction. An engagement between the kinetics of the colour removal rates (ln k2) versus Lazo bond was carried out at the different pH levels. The colour removal rate was increased with decreasing of Lazo bond, in the order of pH: 3.5 > 5.0 > 2.5. The second-order kinetic model provided the best correlation of the data. Effects of various inorganic anions (such as Cl–, SO42-, CO32-, etc.) was studied to enhance the oxidation efficiency of Fenton reaction. Advanced oxidation technologies were developed in this study especially with dealing with contaminated textile wastewater over the use of chemical treatment.
اظهر المزيد [+] اقل [-]Optimization of Incubation Period, pH and Moisture Content for Vermicomposting of Biomethanation Sludge Admixed with Fruits and Vegetable Waste Collected from Gultekadi Market Yard, Pune Using Eudrilus eugeniae
2020
A. I. Mulla , G.R. Pathade
The present study had an objective to optimize important parameters viz., incubation period, pH and moisture per cent for vermicomposting of biomethanation sludge admixed with fruits and vegetable waste collected from Gultekadi Market Yard, Pune using Eudrilus eugeniae. The experiment was conducted on the terrace of H.V. Desai College of Arts, Commerce and Science, Pune. The sludge from biomethanation digester running on fruits and vegetable waste was collected and dewatered. The fruits and vegetable waste was collected from Gultekadi Market Yard, Pune and used for the experiment by processing it. The dewatered sludge was admixed with partially decomposed fruits and vegetable waste. The 1kg working capacity plastic trays were used for the optimization of parameters. It was found that incubation period of six weeks, pH 7.0 and moisture content of 70-80% were the optimum condition for Eudrilus eugeniae vermicomposting. The average growth rate mg/worm/day for the optimized incubation period, pH and moisture % was 4.4±0.14, 5.57±0.1 and 7.5±0.47, respectively and at all the three optimized conditions was 7.8±0.6.
اظهر المزيد [+] اقل [-]Biological Remediation of the Municipal Solid Waste Leachate - A Case Study of Hyderabad Integrated MSW Limited
2020
Konda Durga Sindhu Sree, Surya Narayan Dash and Anagani Leelavathi
A prominent issue associated with the handling of municipal solid waste is the generation of a highly toxic semi-solid matter namely, leachate. The consequences of mishandling the aforementioned are widespread. Hence, the present study tried to take an initiative to remediate the same in an eco-friendly way. The research included a detailed investigation of the existing conditions in terms of quality, quantity, climatic condition, etc. The entire study primarily focused on the biodegradability of the toxic pollutants with the help of EM.1 solution procured from Pragati Enterprises and bringing down the pollution level during the treatment tenure. The major three parameters of interest include chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total dissolved solids (TDS). A pilot pond of 7.5 kL capacity was prepared at the east corner of Hyderabad Integrated MSW facility to facilitate the practical studies. Four major remediates, i.e. coir pith powder, Bokashi balls, EM culture, and Bokashi powder were added weighing 34 MT, 560 kg, 10.5 kL, and 75 kg respectively, over the due course of 4 months and successive reduction in pollution levels were noted. Depletion in the level of all the prior-mentioned parameters was observed ranging 42.6%, 45.4%, and 37.8% respectively for COD, BOD and TDS. Furthermore, a notable reduction in obnoxious odour was observed around the pilot plant after the 15th day of the initiation of the operation. It signifies the feasibility of the experimented technology towards the treatment of municipal solid waste leachate (MSWL), and hence the study recommends the usage of the same as a potential pre-treatment before the tertiary purification units.
اظهر المزيد [+] اقل [-]Interaction Between the Tourism Industry and Ecological Environment Based on the Complicated Adaptation System (CAS) Theory: A Case Study on Henan Province, China
2020
Zhong Wei Wang
Pressure over the destruction of the ecological environment by the tourism industry from the blind development of tourism areas, tourism projects that destroy the ecological environment, tourist overloading during holidays, and poor environmental protection awareness among tourists is increasing. Seeking a balance point between ecological environmental protection and tourism industrial development is key in the sustainable development of the tourism industry. The Complicated Adaptation System (CAS) theory is an important theory in the current system, which focuses on the interaction of the internal elements of a system. Analyzing the interactive development between the tourism industry and the ecological environment based on CAS theory is one way to achieve the harmonious coexistence of the tourism industry and the ecological environment. A case study on Henan Province, China, is conducted, the literature on the interaction between the tourism industry and ecological environment is reviewed, and the environmental pollution status of Henan Province caused by the tourism industry is summarized. Moreover, the complex adaptation of the tourism industry and ecological environment is analyzed. Research results show that most studies support the belief that the tourism industry generates substantial environmental pollution. Environmental pollution from the tourism industry in Henan Province is reflected in tourist overloading, the direct effects of pollution from tourism consumption, damage to cultural relics in star-level tourism areas, and in dwindling habitats for plant and animal survival. Analyzing the interactive relationship between the tourism industry and ecological environment has scientific value and is worth promoting. This relationship is established based on CAS theory from four characteristics, namely, clustering, nonlinearity, flow, and diversity, and three mechanisms, that is, labelling, an internal model, and building blocks. The research conclusions can serve as a reference to better facilitate tourism industry development, estimate the relationship between the tourism economy and ecological environment, and combine ecological tourism and green technological innovation effectively.
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