Removal of copper and nickel from solution by the non-viable biomass of the water fern Azolla filiculoides in an upscaled fixed-bed column system
- Authors: Thompson, Denis Alan
- Date: 2001
- Subjects: Copper , Nickel , Azolla , Heavy metals -- Absorption and adsorption
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3914 , http://hdl.handle.net/10962/d1003973 , Copper , Nickel , Azolla , Heavy metals -- Absorption and adsorption
- Description: The potential of non-viable Azalia filiculaides for the removal of Cu and Ni from aqueous solutions and the possibility of scaling up existing lab scale Azalia column systems was investigated. The effects of factors such as metal starting concentration, pH and two metals in solution on the removal of Ni and Cu from aqueous solution by dried and crushed Azalia biomass were studied in batch systems. Aqueous solutions of Ni with starting concentrations between 1000 and 2000J.lmolll gave the most efficient Ni removal by Azalla biomass. For Cu the optimum starting concentration for adsorption was 50J.lmol/l. The adsorption capacity of both eu and Ni increased as the starting pH of the sorption media increased. The optimum pH for Ni adsorption was found at pH 7 and for Cu, at pH 5. - Awlla biomass had a higher. maximum binding capacity (qrnax) for Cu than for Ni at pH 5. The removal of both Cu allct Ni showed little or no variation with the presence another metal in solution. Kinetic studies show that both Cu and Ni adsorbed rapidly onto the Azalia biomass. The removal of Cu and Ni from aqueous solutions using non-viable Azalia biomass was investigated in a lab scale fixed-bed column and an upscaled 4L column system. The nonviable Azalla filiculaides biomass when dried and used in a column for adsorption of Cu and Ni showed good physical stability under many different conditions. Preparation of the biomass before it could be used in the columns was very simple and did not involve any significant pretreatment steps. Prolonged exposure to UV light decreases Azalia biomass capacity for Ni and Cu adsorption. Column adsorption of Cu and Ni from aqueous solutions was successfully upscaled approximately 100 times. Relative to the lab scale column, the 4L column performed better for the uptake of Cu and Ni per gram of biomass. The larger column was also able to operate at relatively higher flow rates. The biomass showed good reusability with little change in the amount of Ni adsorbed in 10 consecutive cycles. Electron micrographs showecf little or no change in the physical structure and integrity of the Azolla biomass after exposure to mineral acids, Ni solution and high flow rates over 10 consecutive adsorption and desorption cycles. As much as 80% Ni and 70 % Cu was recovered when desorption profiles were generated using O.lMHCI as a desorption agent. The 4L column system was also tested using a highly concen~rat:~ Ni plating bath solution.(Nicrolyte 1). Only 18 % of the Ni could be removed from the expended Nicrolyte 1 pla~Jng solution after treating only 25L, indicating that Azolla biomass is more suited for removal of metals from more dilute industrial effluents.
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- Date Issued: 2001
Removal of lead from solution by the non-viable biomass of the water fern Azolla filiculoides
- Authors: Sanyahumbi, Douglas
- Date: 1999
- Subjects: Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3901 , http://hdl.handle.net/10962/d1003960 , Azolla , Heavy metals -- Absorption and adsorption , Lead , Water -- Purification -- Biological treatment
- Description: The removal of lead from aqueous solution and lead-acid battery manufacturing waste-water by the non-viable biomass of the water fern Azolla filiculoides was investigated in both batch and column reactors. The maximum lead uptake by the Azolla biomass at a pH value of approximately 5, was found to be 100 mg lead/g biomass from aqueous solution. Lead removal varied from 30% of the initial lead concentration at pH 1.5 to approximately 95% at pH values of 3.5 and 5.6. Lead removal from aqueous solution decreased to 30% of the initial lead concentration if the lead concentration was initially over 400 mg/l. At initial lead concentrations of less than 400 mg/l, percentage lead removal was found to be over 90% of the initial lead concentration. Lead removal remained at approximately 90% between 10°C and 50°C. Biomass concentration (4-8 mg/l) had little effect on lead removal. The presence of iron (Fe) and lead, copper (Cu) and lead or all three metal ions in solution at varying ratios to each other did not appear to have any significant effect on lead removal. Percentage lead, copper and iron removal from aqueous solution was 80-95, 45-50 and 65-75% respectively for the different multiple-metal solutions studied. No break-through points were observed for lead removal from aqueous solutions in column reactors, with initial lead concentrations of less than 100 mg/l at varying flow rates of 2, 5 and 10 ml/min. This suggested that flow rate, and therefore retention time, had little effect on percentage lead removal from aqueous solution, which was more that 95%, at low initial lead concentrations (less than 100 mg/l). At initial lead concentrations of 200 mg/l or more, an increase in flow rate, which equates to a decrease in column retention time, resulted in break-through points occurring earlier in the column run. Percentage lead removal values, from lead-acid battery efiluent in column systems, of over 95% were achieved. Desorption of approximately 30% and 40% of bound lead was achieved, with 0.5 M HNO₃ in a volume of 50 ml, from two lead-acid battery. Repeated adsorption and desorption of lead by the Azalia biomass over 10 cycles did not result in any decrease in the percentage lead removal from effluent, which strongly suggested that the Azalla biomass could be re-used a number of times without deterioration in its physical integrity, or lead removal capacity. No evidence of deterioration in the Azolla biomass's physical integrity after 10 successive adsorption and desorption procedures was observed using scanning electron microscopy. The Azolla filiculoides biomass was, therefore, found to be able to effectively remove lead from aqueous solution and lead-acid battery effluent repeatedly, with no observed reduction in it's uptake capacity or physical integrity.
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- Date Issued: 1999
The removal of toxic heavy metals from aqueous solutions by algal extracellular polysaccharides
- Authors: Selepe, Mamaropeng Marcus
- Date: 1999
- Subjects: Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3994 , http://hdl.handle.net/10962/d1004054 , Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Description: This study investigated the possible use of algal extracellular polysaccharide as a biosorbent for removal of heavy metals (copper and lead) from aqueous solutions as a means of bioremediation for metal containing effluents. This biopolymer has good biosorbent properties and a potential to provide a cost effective, selective and efficient purification system. A variety of environmental conditions induce the production of extracellular polysaccharides in algae. The production of exopolysaccharides by Dunaliella cultures was induced by nitrogen deficient conditions. A high ratio of carbon to nitrogen source considerably enhanced the polysaccharide release. Purified extracellular polysaccharide samples exhibited a monosaccharide composition consisting of the following sugars: xylose, arabinose, 2-0-methyl mannose, mannose, glucose and galactose. The relative abundance (%) of these sugars were calculated relative to xylose. The major sugar constituent was 2-0-methyl mannose, which was present at approximately 160% relative to xylose. The percentage relative abundance of other sugars was as follows: 18.8; 86.8; 85.3 and 22.3% for arabinose; mannose; glucose and galactose respectively. The identity of the various constituents were confirmed by mass spectrometry. The ability of Dunaliella exopolysaccharides to accumulate metals was investigated. The following parameters were studied because they affect metal uptake: solution pH, biomass concentration, temperature, time and metal concentration. The uptake of both copper and lead were pH dependent. However, metal uptake was not significantly affected by temperature. Kinetic studies showed that Dunaliella extracellular polysaccharides exhibit good bioremediation properties. Metal uptake was rapid. In addition, the exopolysaccharide has good metal binding capacity with an uptake capacity for lead of 80 mg/g from a solution containing initial lead concentration of approximately 40 mg/l. Competition studies revealed that the presence of a second metal in solution inhibits uptake of the other metal compared to uptake in single metal solution of that particular metal. The presence of lead inhibited the uptake of copper from approximately 65% in single metal solution to 10% in binary metal solution. The presence of copper also inhibited lead uptake, though not to the same extent. Higher concentrations of lead could not completely prevent removal of copper from solution and visa versa. The same was true for lead which could not be displaced by a four-fold concentration of copper. Instead, a certain percentage of copper was always removed showing that lead did not compete with copper for these binding sites. In conclusion it appears that, copper and lead bind to different sites on Dunaliella exopolysaccharides and that they exhibit selective or preferential removal of lead.
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- Date Issued: 1999
The effect of varying heavy metal balances in the nutrient medium, on the growth and development of Aspergillus Sp. and Penicillium Sp.
- Authors: Breen, C M
- Date: 1965
- Subjects: Heavy metals -- Absorption and adsorption , Aspergillus -- Growth , Penicillium -- Growth , Fungi -- Nutrition
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4268 , http://hdl.handle.net/10962/d1014597
- Description: The study was conducted to investigate the effects of: (i) varying the level of supply of the heavy metals iron, manganese, copper and zinc. (ii) varying the ratio between different pairs of metals in the medium. In particular the iron:manganese and zinc:copper ratios were studied. Initially the two fungi Aspergillus niger van Tieghem, (variety and strain) and Penicillium notatum Westling, were used. Penicillium notatum Westling was subsequently discarded, in favour of Penicillium glancum Link, because it did not sporulate freely in liquid culture. The fungi were grown in controlled nutrient solutions, and during the course of tho growth and development, the form and sporulation of the felts was noted. After a period of growth, the felts were removed, dried and weighed. The pH of the liquor was measured. the results were studied to determine the effect of varying levels of supply of the heavy metals, and of the varying heavy metal ratios in the culture solution. In the investigation of the effect of varying the level of supply of individual heavy metals, optimum concentrations were demonstrated for copper and manganese. Increaning the concentration of pairs of heavy metals cimultaneously was found to influence the appearance and degree of symptoms of toxicity. Cultures of Aspergillus and Penicillium were found to be able to tolerate concentrations of copper, in particular, considerably greater than the observed optima, when zinc was present in equal concentration. Citric acid, and subsequently ethylene- diaminetetra-acetic acid, were used as chelating agents, in order to prevent the precipitation of the metals in the culture solution during autoclaving. It was found that the use of chelating agents markedly reduced symptoms of toxicity. There was no conclusive evidence that the iron:manganese ratio in the culture medium was an important factor in the growth and development of cultures of Aspergillus and Penicillium. However there is considerable evidence that in cultures of Penicillium, the zinc:copper ratio in the medium is of some importance in the determination of the dry weight yield trends. This effect was not demonstrated in cultures of Aspergillus.
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- Date Issued: 1965