In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are ...In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,constant.The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min.The saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/mg.min,respectively.Using the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%breakthrough.The Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.展开更多
Sludge contains organic and inorganic compounds including traces of heavy metals such as lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), chromium (Cr) and others. These metals restrict the use of sludge in agricult...Sludge contains organic and inorganic compounds including traces of heavy metals such as lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), chromium (Cr) and others. These metals restrict the use of sludge in agriculture because their accumulation is harmful to the environment and particularly the food chain. Cadmium and lead are among the most common heavy metals found in municipal wastewater treatment plant sludge. They are capable of bioaccumulation in plant tissues like roots and leaves and are non-biodegradable and therefore they remain in the sludge which is disposed on land or used as fertilizers on farms. The presence of heavy metal pollutants serves as a great threat to soils and also makes plants grown on such soils unfit for animal and human consumption as they may have detrimental effects to animal and human life. For instance, Pb and Cd are known to be human carcinogens. This study therefore aimed to investigate the levels of Cd and Pb in the treated dry sludge from Lubigi Feacal Sludge and Wastewater treatment plant located in Kawempe division, Kampala city, Uganda so as to ascertain its safety for use on agricultural lands. Two batches of samples were collected and analyzed at Government Analytical laboratory in Wandegeya, Uganda. The acid digested sludge samples were analyzed using Atomic Absorption Spectroscopy (AAS) method. The average concentrations of Pb found in collected sludge samples, batch 1 (11.912 mg/kg dm) and batch 2 (5.304 mg/kg dm) were far below the Environment Protection Agency (EPA) maximum permissible concentration (840 mg/kg) for any land application. Cadmium was not detected in all the sludge samples collected;there is an implication that it is either completely absent in the sludge generated by the plant or present but far below detectable levels. The sludge generated from Lubigi fecal sludge and wastewater treatment plant is therefore safe for application on agricultural lands as far as Pb and Cd concentrations are concerned.展开更多
The appropriate condition and scheme of removing cadmium from electroplating wastewater were investigated by adsorption-precipitation method using waste saccharomyces cerevisiae(WSC) as sorbent. Effect factors on bios...The appropriate condition and scheme of removing cadmium from electroplating wastewater were investigated by adsorption-precipitation method using waste saccharomyces cerevisiae(WSC) as sorbent. Effect factors on biosorption of cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae and precipitation process of waste saccharomyces cerevisiae after adsorbing cadmium were studied. The results show that removal rate of cadmium is over 88% after 30 min adsorbing under the condition of cadmium concentration 26 mg/L, the dosage of waste saccharomyces cerevisiae 16.25 g/L, temperature 18 ℃, pH 6.0 and precipitation time 4 h. Biosorption-precipitation method is effective to remove cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae. The SEM, infrared spectroscopy and Zeta-potential of the cells show that chemical chelating is the main adsorption form; electrostatic attraction, hydrogen bonding and van der Waals force all function in adsorption process; and ―NH2―,―C=O―,―C=O―NH―,―CH3, ―OH are the main adsorption groups.展开更多
In hospital, a variety of substances are in use for medical purposes as diagnostics and researches. Among them, heavy metals which are not biodegradable by chemical reactions have bioaccumulation properties. Cadmium i...In hospital, a variety of substances are in use for medical purposes as diagnostics and researches. Among them, heavy metals which are not biodegradable by chemical reactions have bioaccumulation properties. Cadmium is a toxic pollutant that enters hospital wastewaters by different ways. However, isolated bacteria from hospital effluents have high resistance to antimicrobial agents and therefore the ability to uptake cadmium and other metals. So, their use is recommended for wastewater bioremediation. In this study, twelve cadmium-resistant bacteria were isolated from hospital wastewaters and identified. The cadmium-resistant isolates characterized include both Gram-negative [75%] and Gram-positive [25%]. The Minimum Inhibitory Concentration of hospital wastewaters isolates was determined in solid media and was ranged from 250 to 950 micrograms/milliliters. All the isolates showed co-resistance to zinc and mercury. They were also antibiotic resistant and tolerated up a significant concentration of NaCl. The cadmium-resistant species Klebsiella pneumoniae and Pseudomonas aeruginosa were the most resistant to cadmium. The species Klebsiella pneumonia also resists to the highest concentrations of zinc and mercury. The results of toxicity tests on Vibrio fischeri, showed that the DI50 [15 min] as low as 0.07 carried away 50% luminescence inhibition.展开更多
The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to...The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to the application of fish bone in nanoform as a useful, inexpensive and eco-friendly alternative material. A comparison between natural hydroxyapatite (fish bone), synthetic hydroxyapatite nanoparticles (HAP) and alginate-hydroxyapatite composite (Alg/Hap) to assess their removal efficiencies to remediate the selected heavy metals has been done. Surface characterization by using different techniques has also been performed to understand the influence of surface characteristics of the adsorbent materials in the removal process. Different parameters (pH, contact time, mass dose and metal ion concentration) have been examined to identify the optimum conditions for remediation of different metals from polluted water. The potential applications of the biosorbents for removal and sorption of these metal ions from seawater and wastewater samples were also investigated and evaluated.展开更多
Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparat...Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparation of biochar requires the thermochemical conversion of biomass in an oxygen-restricted environment. Different raw materials and preparation processes result in biochar with different internal structures and biofunctional groups, which often have different properties. Adsorption of heavy metal pollutants is one of the main research directions for biochar application, and there are still areas that can be improved in the current research for biochar for treating heavy metal wastewater. In this study, we take the treatment of cadmium-containing wastewater as an example, walnut shell biochar (WSBC) as a carrier, iron(VI) compounds as a modifying reagent, and test the performance of cadmium-containing wastewater treatment using simulated cadmium-containing wastewater by adjusting the pyrolysis process and modification method at the same time to find the optimal experimental scheme, and give a reasonable theoretical explanation in relation to the results of the characterization tests, such as SEM, FT-IR, and so on. The characterized results show that iron(VI) compound (K<sub>2</sub>FeO<sub>4</sub>)-modified WSBC has a significant ability to remove cadmium contamination in the wastewater (remove 96.62% of cadmium in 1 minute), and its structure is different from other iron compound-modified ones. The aim of this study is to improve the efficiency of cadmium adsorption by specific types of biochar, while realizing the whole process as environmentally friendly as possible.展开更多
文摘In this study,the potential of a low-cost bio-adsorbent,taken directly from Date Palm Trunk Fibers(DPTF)agricultural wastes,for cadmium ions removal from wastewaters is examined.The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters,such as the initial feed concentration,pH,and particle size,constant.The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min.The saturation concentrations(NO)and the rate constant(kab)obtained from the BDST(bed depth service time)model are 7022.16 mg/l and 0.0536 l/mg.min,respectively.Using the Yon-Nelsen Model,it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50%breakthrough.The Wolborska model indicates that the bed capacity increases with decreasing the flow rate,and the adsorbent can achieve a greater external mass transfer kinetic coefficient(2.271/min)at a higher flow rate.
文摘Sludge contains organic and inorganic compounds including traces of heavy metals such as lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), chromium (Cr) and others. These metals restrict the use of sludge in agriculture because their accumulation is harmful to the environment and particularly the food chain. Cadmium and lead are among the most common heavy metals found in municipal wastewater treatment plant sludge. They are capable of bioaccumulation in plant tissues like roots and leaves and are non-biodegradable and therefore they remain in the sludge which is disposed on land or used as fertilizers on farms. The presence of heavy metal pollutants serves as a great threat to soils and also makes plants grown on such soils unfit for animal and human consumption as they may have detrimental effects to animal and human life. For instance, Pb and Cd are known to be human carcinogens. This study therefore aimed to investigate the levels of Cd and Pb in the treated dry sludge from Lubigi Feacal Sludge and Wastewater treatment plant located in Kawempe division, Kampala city, Uganda so as to ascertain its safety for use on agricultural lands. Two batches of samples were collected and analyzed at Government Analytical laboratory in Wandegeya, Uganda. The acid digested sludge samples were analyzed using Atomic Absorption Spectroscopy (AAS) method. The average concentrations of Pb found in collected sludge samples, batch 1 (11.912 mg/kg dm) and batch 2 (5.304 mg/kg dm) were far below the Environment Protection Agency (EPA) maximum permissible concentration (840 mg/kg) for any land application. Cadmium was not detected in all the sludge samples collected;there is an implication that it is either completely absent in the sludge generated by the plant or present but far below detectable levels. The sludge generated from Lubigi fecal sludge and wastewater treatment plant is therefore safe for application on agricultural lands as far as Pb and Cd concentrations are concerned.
基金Project(50174014) supported by the National Natural Science Foundation of ChinaProject(20042021) supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2006223002) supported by the High Science and Technology Plan of Liaoning Province,China
文摘The appropriate condition and scheme of removing cadmium from electroplating wastewater were investigated by adsorption-precipitation method using waste saccharomyces cerevisiae(WSC) as sorbent. Effect factors on biosorption of cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae and precipitation process of waste saccharomyces cerevisiae after adsorbing cadmium were studied. The results show that removal rate of cadmium is over 88% after 30 min adsorbing under the condition of cadmium concentration 26 mg/L, the dosage of waste saccharomyces cerevisiae 16.25 g/L, temperature 18 ℃, pH 6.0 and precipitation time 4 h. Biosorption-precipitation method is effective to remove cadmium in cadmium-containing electroplating wastewater by waste saccharomyces cerevisiae. The SEM, infrared spectroscopy and Zeta-potential of the cells show that chemical chelating is the main adsorption form; electrostatic attraction, hydrogen bonding and van der Waals force all function in adsorption process; and ―NH2―,―C=O―,―C=O―NH―,―CH3, ―OH are the main adsorption groups.
文摘In hospital, a variety of substances are in use for medical purposes as diagnostics and researches. Among them, heavy metals which are not biodegradable by chemical reactions have bioaccumulation properties. Cadmium is a toxic pollutant that enters hospital wastewaters by different ways. However, isolated bacteria from hospital effluents have high resistance to antimicrobial agents and therefore the ability to uptake cadmium and other metals. So, their use is recommended for wastewater bioremediation. In this study, twelve cadmium-resistant bacteria were isolated from hospital wastewaters and identified. The cadmium-resistant isolates characterized include both Gram-negative [75%] and Gram-positive [25%]. The Minimum Inhibitory Concentration of hospital wastewaters isolates was determined in solid media and was ranged from 250 to 950 micrograms/milliliters. All the isolates showed co-resistance to zinc and mercury. They were also antibiotic resistant and tolerated up a significant concentration of NaCl. The cadmium-resistant species Klebsiella pneumoniae and Pseudomonas aeruginosa were the most resistant to cadmium. The species Klebsiella pneumonia also resists to the highest concentrations of zinc and mercury. The results of toxicity tests on Vibrio fischeri, showed that the DI50 [15 min] as low as 0.07 carried away 50% luminescence inhibition.
文摘The main objective of this paper is to study the removal of Cadmium(II), Lead(II), Chromium(VI), and Mercury(II) ions by sorption onto different natural and synthetic nanoparticles. Special attention has been given to the application of fish bone in nanoform as a useful, inexpensive and eco-friendly alternative material. A comparison between natural hydroxyapatite (fish bone), synthetic hydroxyapatite nanoparticles (HAP) and alginate-hydroxyapatite composite (Alg/Hap) to assess their removal efficiencies to remediate the selected heavy metals has been done. Surface characterization by using different techniques has also been performed to understand the influence of surface characteristics of the adsorbent materials in the removal process. Different parameters (pH, contact time, mass dose and metal ion concentration) have been examined to identify the optimum conditions for remediation of different metals from polluted water. The potential applications of the biosorbents for removal and sorption of these metal ions from seawater and wastewater samples were also investigated and evaluated.
文摘Biochar is a functional and environmentally friendly material mainly made from by-products of industrial and agricultural production as raw material, which is cracked at high temperatures and slow speeds. The preparation of biochar requires the thermochemical conversion of biomass in an oxygen-restricted environment. Different raw materials and preparation processes result in biochar with different internal structures and biofunctional groups, which often have different properties. Adsorption of heavy metal pollutants is one of the main research directions for biochar application, and there are still areas that can be improved in the current research for biochar for treating heavy metal wastewater. In this study, we take the treatment of cadmium-containing wastewater as an example, walnut shell biochar (WSBC) as a carrier, iron(VI) compounds as a modifying reagent, and test the performance of cadmium-containing wastewater treatment using simulated cadmium-containing wastewater by adjusting the pyrolysis process and modification method at the same time to find the optimal experimental scheme, and give a reasonable theoretical explanation in relation to the results of the characterization tests, such as SEM, FT-IR, and so on. The characterized results show that iron(VI) compound (K<sub>2</sub>FeO<sub>4</sub>)-modified WSBC has a significant ability to remove cadmium contamination in the wastewater (remove 96.62% of cadmium in 1 minute), and its structure is different from other iron compound-modified ones. The aim of this study is to improve the efficiency of cadmium adsorption by specific types of biochar, while realizing the whole process as environmentally friendly as possible.