https://vital.seals.ac.za/vital/access/manager/Index ${session.getAttribute("locale")} 5 https://vital.seals.ac.za/vital/access/manager/Repository/vital:3910 Wed 21 Jul 2021 13:46:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3913 Wed 12 May 2021 23:37:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4044 Wed 12 May 2021 23:36:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4053 Wed 12 May 2021 23:35:03 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4008 Wed 12 May 2021 23:29:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4067 Wed 12 May 2021 22:58:05 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3895 Wed 12 May 2021 22:51:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:20972 Wed 12 May 2021 20:55:41 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4155 Wed 12 May 2021 20:51:24 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4055 Wed 12 May 2021 20:37:25 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4038 Wed 12 May 2021 20:37:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4065 Wed 12 May 2021 20:35:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4042 Wed 12 May 2021 20:35:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4050 Wed 12 May 2021 20:33:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3907 Wed 12 May 2021 20:12:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4033 Wed 12 May 2021 20:01:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3908 Wed 12 May 2021 19:53:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4035 Wed 12 May 2021 19:50:33 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4043 Wed 12 May 2021 19:40:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4007 Wed 12 May 2021 19:29:13 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3982 Wed 12 May 2021 19:21:42 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4037 Wed 12 May 2021 19:17:17 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3933 Wed 12 May 2021 19:16:50 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3976 Wed 12 May 2021 18:46:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4017 Wed 12 May 2021 18:40:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4002 cadmium > cobalt > zinc > copper > chromium > nickel. A rapid method to assess metal recovery was developed. Bioaccumulated metal was efficiently recovered using dilute mineral acids. Copper recovery of ≥ 80 % was achieved by decreasing the solution pH of the reaction mixture to 2 with the addition of nominal quantities of HCl, H₂SO₄ or RNO₃. Adsorption-desorption over 8 cycles had no apparent adverse effect on metal uptake or recovery in batch reactors. Transmission electron microscopy showed no evidence of damage to cells used in copper adsorption-desorption investigations. Biosorption columns were investigated as bioreactors due to their application potential. The metals investigated were effectively removed from solution. At a saturation threshold, metal uptake declined rapidly. Most metals investigated were desorbed from the columns by eluting with 0.1 M HCl. Initially recoveries of copper, cobalt and cadmium were as high as 100%. Desorbed copper, zinc, cadmium, nickel and cobalt were concentrated in 10 to 15 ml of eluent, representing up to a 40 fold decrease in solution volume. Cadmium, nickel and zinc uptake increased with the second application to the columns. Initial accumulation of gold and chromium was 42.2 μmol/g and 28.6 μmol/g, however, due to the low recoveries of these two metals, a second application was not investigated. Copper was applied to a single column for 8 consecutive adsorption-desorption cycles. Uptake increased from an initial 31.3 μmol/g to 47.8 μmol/g at cycle 7. The potential for selective metal recovery was demonstrated using two biosorption columns in series. Copper was accumulated and recovered most efficiently. Zinc, cobalt and cadmium were displaced to the second column. Copper bound preferentially to zinc at a ratio of 6:1. Copper bound preferentially to cobalt at a ratio of 4:1. Cadmium was only displaced at a ratio of 2:1. The successful transfer of the bioremediation technology from the laboratory to an industrial application has yet to be realized. Bioremediation of a Plaatjiesvlei Black Mountain mine effluent, which contained copper, zinc, lead and iron, was investigated in this project. The removal of the metals was most effective at pH 4. A combined strategy of pH adjustment and bioremediation using immobilized S. cerevisiae decreased the copper concentration by 92.5%, lead was decreased by 90% and zinc was decreased by 60%. Iron was mostly precipitated from solution at pH ≥ 4. An ageing pond at the mine with conditions such as; pH, water volume and metal concentration, which were more conducive to biological treatment was subsequently identified. The investigation indicated a possible application of the biomass as a supplement to chemical remediation. The metal removal capability of a waste brewer's yeast was subsequently investigated. A yeast conditioning step increased metal uptake up to 100% and enhanced reproducibility. Metal removal from solution was rapid and pH dependent. The metals were efficiently removed from solution at pH ≥ 4. Uptake was substantially inhibited at pH ≤ 3. The waste brewer's yeast accumulated metals with maximum binding capacities in the order of copper (25.4 μmol/g) > lead (19.4 μmol/g) > iron (15.6 μmol/g) > zinc (12.5 μmol/g). No correlation between cell physiology and metal uptake was observed. Uptake of the four metals was confirmed by energy dispersive X-ray microanalysis. The interference of lead, zinc and iron on copper uptake by the waste brewer's yeast, and the interference of copper on the uptake of lead, zinc and iron was investigated. Maximum copper uptake was not decreased in the presence of lead. The Bmax remained constant at approximately 25 μmol/g. The dissociation constants increased with increasing lead concentrations. Lead bioaccumulation was significantly decreased in the presence of copper. The type of inhibition was dependent on the initial copper concentrations. Zinc had a slight synergistic effect on copper uptake. The copper Bmax increased from 30.8 μmol/g in a single-ion system to 34.5 μmol/g in the presence of 200 μmol/l of zinc. Zinc uptake was severely inhibited in the presence of copper. The maximum uptake and dissociation constant values were decreased in the presence of copper, which suggested an uncompetitive inhibition. The affinity of copper was substantially higher than zinc. The presence of higher levels of copper than zinc in the yeast cells was confirmed by energy dispersive microanalysis. Copper uptake was decreased in the presence of iron, with the copper Bmax being decreased from 25.4 μmol/g in a single-ion system to 20.1 μmol/g in the presence of 200 μmol/l iron. Iron Bmax values remained constant at 16.0 μmol/g. Combined biosorption and EDXA results suggested the iron bound at a higher affinity than copper to the cell wall. Total copper removal was higher as larger quantities of copper were deposited in the cell cytoplasm. Metal removal from the Plaatjiesvlei effluent by free cell suspensions of the waste brewer's yeast was satisfactory. Copper levels were decreased by 96%, iron by 42%, lead 25% and zinc 2%. Waste brewer's yeast is a cheap source of biomass in South Africa, and could potentially provide the basis for the development of an innovative purification system for metal-contaminated waters.]]> Wed 12 May 2021 18:32:15 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4078 Wed 12 May 2021 18:28:46 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3909 Wed 12 May 2021 18:26:34 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4001 Wed 12 May 2021 18:20:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4058 Wed 12 May 2021 18:16:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3903 Wed 12 May 2021 18:01:10 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3905 Wed 12 May 2021 17:51:47 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3901 Wed 12 May 2021 17:35:49 SAST ]]> 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12 May 2021 16:27:32 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4036 Wed 12 May 2021 16:13:35 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3894 Wed 12 May 2021 16:06:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4034 Wed 12 May 2021 16:06:36 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3906 Wed 12 May 2021 16:01:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3988 Wed 12 May 2021 15:56:54 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4048 Wed 12 May 2021 15:55:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4000 Wed 12 May 2021 15:46:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3879 Thu 13 May 2021 16:00:27 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4084 Thu 13 May 2021 15:33:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4040 Thu 13 May 2021 14:22:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4023 Thu 13 May 2021 08:13:31 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4010 Thu 13 May 2021 07:34:45 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4104 Thu 13 May 2021 07:27:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4049 Thu 13 May 2021 07:11:14 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4054 Thu 13 May 2021 07:09:16 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3919 Thu 13 May 2021 07:05:18 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4046 Thu 13 May 2021 06:51:04 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4019 Thu 13 May 2021 06:49:55 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4020 Thu 13 May 2021 06:21:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4052 Thu 13 May 2021 06:17:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3998 Thu 13 May 2021 06:13:01 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3915 Thu 13 May 2021 06:08:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4061 Thu 13 May 2021 05:54:49 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3914 Thu 13 May 2021 05:08:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3904 Thu 13 May 2021 05:05:44 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3917 Thu 13 May 2021 05:04:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4124 Thu 13 May 2021 05:02:48 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3898 Thu 13 May 2021 05:02:23 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3994 Thu 13 May 2021 04:50:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3969 Thu 13 May 2021 04:40:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3911 Thu 13 May 2021 04:33:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4041 Thu 13 May 2021 04:32:37 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4029 Thu 13 May 2021 04:31:38 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4079 Thu 13 May 2021 04:31:19 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4051 Thu 13 May 2021 04:29:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4100 Thu 13 May 2021 03:58:08 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4012 Thu 13 May 2021 03:57:39 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4016 Thu 13 May 2021 03:57:00 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3880 Thu 13 May 2021 03:40:51 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3916 Thu 13 May 2021 03:16:52 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4015 chitin> glucan > intact cell walls exists. However, these components differ in their affinities for metal ions. Storage of metal ions within the cell occurs predominantly in the vacuole. The present study concluded that metal accumulation by the vacuole could be related to size. Metal accumulation occurred in the order of Cu2+ > Co2+ > Cd2+ with a corresponding decrease in atomic radii of Cd2+ > C02+ > Cu2+. Vacuolar ion deposition occurs at an early stage during the internalization of metal ions within the yeast cells. At the onset of vacuolar saturation, depositions of metal ions as granules within the cytosol occurs. In the presence of heavy metal cations viable yeast cells can be shown to exhibit two types of cellular responses. Uptake of Cu2+ and Cd2+ causes the loss of intracellular physiological cations from within the yeast cell. In comparison, uptake of Co2+ into the cell does not have this effect. All three heavy metal cations initiate plasma cell membrane permeability, thus the Cu2+ and Cd2+ induced loss of the intracellular cations, occurs. ~ a result of ion-exchange mechanisms and not due to cation leakage brought about by membrane permeabilization. Uptake of heavy metals by viable yeasts appears to be generally non-selective though the amount of metals accumulated are largely affected by the ratio of ambient metal concentration to biomass quantity. In addition, the energy dependent nature of internalization necessitates the availability of an external energy source for metal uptake by viable yeast cells. For these reasons metal removal from industrial waste water was investigated using non-viable biomass. By immobilizing the yeast cells additional mechanical integrity and stability was conferred apon the biomass. The three types of biomass preparations developed in this study, viz. polyvinyl alcohol (PV A) Na-alginate, PV A Na-orthophosphate and alkali treated polyethylenimine (PEI):glutaraldehyde (GA) biomass pellets, all fulfilled the necessary physical requirements. However, the superior metal accumulating properties of the PEI:GA biomass determined its selection as a biosorbent for bioremediation purposes. Biosorption of heavy metals by PEI:GA biomass is of a competitive nature, with the amount of metal accumulated influenced by the availability of the metal ions. This availability is largely determined by the solution pH. At low pH values the affinity of the biomass for metals decreases, whilst enhanced metal biosorption occurs at higher pHs, ego pH 4.5 - 6.0. PEI:GA biomass pellets can be implemented -as a biosorbent for the bi9remediaiton of high concentration, low-volume metal containing industrial waste. Several options regarding the bioremediation system are available. Depending on the concentration of the metals in the effluent, the bioremediation process can either be used independently or as part of a biphasic remediation system for the treatment of waste water. Initial phase chemical modification may be required, whilst two types of biological systems can be implemented as 'part of the second phase. The PEI:GA biomass can either be contained within continuous-flow fixed bed tanks or continuous-flow stirred bioreactor tanks. Due to the simplicity of the process and the ease with which scale-up is facilitated, the second type of system shows greater application potential for the treatment of this type of industrial waste water than the fixed-bed systems.]]> Thu 13 May 2021 02:58:09 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3918 Thu 13 May 2021 02:17:58 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4045 Thu 13 May 2021 02:07:26 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3902 Thu 13 May 2021 01:49:22 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4030 Thu 13 May 2021 01:34:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4047 Thu 13 May 2021 01:29:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3900 Thu 13 May 2021 01:07:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4006 Thu 13 May 2021 01:04:21 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:3912 Thu 13 May 2021 01:02:30 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4031 Thu 13 May 2021 01:00:06 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4056 Thu 13 May 2021 00:37:11 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4018 Thu 13 May 2021 00:24:29 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4014 Thu 13 May 2021 00:14:43 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45334 Fri 19 Nov 2021 09:15:59 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:45333 Fri 19 Nov 2021 08:33:53 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4028 Fri 06 Aug 2021 10:23:20 SAST ]]> https://vital.seals.ac.za/vital/access/manager/Repository/vital:4032 Fri 05 Jul 2024 09:51:13 SAST ]]>