http://hdl.handle.net/11189/3431 2026-08-13T01:58:44Z 2026-08-13T01:58:44Z Ntwampe, Seteno Karabo Obed Sheldon, Marshall Sheerene Volschenk, H http://hdl.handle.net/11189/6261 2020-08-12T12:27:28Z 2008-01-01T00:00:00Z

Title: Oxygen mass transfer for an immobilised biofilm of Phanerochaete chrysosporium in a membrane gradostat reactor Authors: Ntwampe, Seteno Karabo Obed; Sheldon, Marshall Sheerene; Volschenk, H Abstract: A novel system, the membrane gradostat reactor (MGR), designed for the continuous production of secondary metabolites, has been shown to have higher production per reactor volume than batch culture systems. The MGR system mimics the natural environment in which wild occurring microorganism biofilms flourish. The biofilms are immobilised on the external surface of an ultrafiltration membrane where substrate distribution gradients are established across the biofilm. The hypothesis that, dissolved oxygen (DO) mass transfer parameters obtained in submerged pellets can be used to describe and model DO mass transfer parameters in the MGR, was refuted. Phanerochaete chrysosporium biofilms, immobilised on ultrafiltration capillary membranes in the MGR systems were used to quantify DO distribution using a Clark-type microsensor. The DO penetration depth decreased with increasing biofilm thickness, which resulted in the formation of anaerobic zones in the biofilms. Oxygen flux values of 0.27 to 0.7 g/(m2.h) were obtained during the MGR operation. The consumption of oxygen and the Monod saturation constants used in the modelling of oxygen distribution in immobilised biofilms were in the range of 894.53 to 2739.70 g/(m3.h) and 0.041 to 0.999 g/m3, respectively.

2008-01-01T00:00:00Z Tombo, Elie Fereche Itoba Waxa, Anda Ntwampe, Seteno Karabo Obed http://hdl.handle.net/11189/5998 2020-08-12T12:02:05Z 2015-01-01T00:00:00Z

Title: Isolation of an Endophytic Cyanide resistant fungus Cunninghamella bertholletiae from (Manihot esculenta) and Cassava cultivated soil for Environmental Engineering Applications Authors: Tombo, Elie Fereche Itoba; Waxa, Anda; Ntwampe, Seteno Karabo Obed Abstract: An endophytic cyanide resistant fungus Cunninghamella bertholletiae was isolated from cassava (Manihot esculenta) and cassava attached silt. The Cunninghamella sp. was sub-cultured into nutrient broth containing KCN (4mg/40mL) as a source of free cyanide. Samples were placed in an orbital (incubator) shaker at 30°C and 130rpm for 120 h. The cyanide resistant isolate was then successfully sub-cultured on PDA for 168 h at room temperature to determine if it can be regenerated after exposure to free cyanide. The fungus identification was based on; plate morphology, microscopic structure observation, nucleotide sequences and phylogenetic analysis. The identification revealed the fungus was Cunninghamella bertholletiae species from the Cunninghamella genus. The fungus has potential to be used as a free cyanide and total nitrogen degrader for environmental engineering applications. Cyanide, ammonium nitrogen and nitrate-nitrogen removal achieved were; 80%, 77.5% and 72.5%, within 120 h respectively. Description: 7th International Conference on Latest Trends in Engineering & Technology (ICLTET'2015) Nov. 26-27, 2015 Irene, Pretoria (South Africa)

2015-01-01T00:00:00Z Mekuto, Lukhanyo Alegbeleye, Oluwadara Oluwaseun Ntwampe, Seteno Karabo Obed Ngongang, Maxwell Mewa Mudumbi, John Baptist Nzukizi Akinpelu, Enoch Akinbiyi http://hdl.handle.net/11189/5601 2020-08-12T12:06:01Z 2016-01-01T00:00:00Z

Title: Co-metabolism of thiocyanate and free cyanide by Exiguobacterium acetylicum and Bacillus marisflavi under alkaline conditions Authors: Mekuto, Lukhanyo; Alegbeleye, Oluwadara Oluwaseun; Ntwampe, Seteno Karabo Obed; Ngongang, Maxwell Mewa; Mudumbi, John Baptist Nzukizi; Akinpelu, Enoch Akinbiyi Abstract: The continuous discharge of cyanide-containing effluents to the environment has necessitated for the development of environmentally benign treatment processes that would result in complete detoxification of the cyanide-containing wastewaters, without producing additional environmental toxicants. Since biological detoxification of hazardous chemical compounds has been renowned for its robustness and environmental-friendliness, the ability of the Exiguobacterium acetylicum (GenBank accession number KT282229) and Bacillus marisflavi (GenBank accession number KR016603) to co-metabolise thiocyanate (SCN−) and free cyanide (CN−) under alkaline conditions was evaluated. E. acetylicum had an SCN− degradation efficiency of 99.9 % from an initial SCN− concentration of 150 mg SCN−/L, but the organism was unable to degrade CN−. Consequently, B. marisflavi had a CN− degradation efficiency of 99 % from an initial concentration of 200 mg CN−/L. Similarly, the organism was unable to degrade SCN−; hence, this resulted in the evaluation of co-metabolism of SCN− and CN− by the two microbial species. Optimisation of operational conditions was evaluated using response surface methodology (RSM). A numeric optimisation technique was used to evaluate the optimisation of the input variables i.e. pH, temperature, SCN− and CN− concentrations. The optimum conditions were found to be as follows: pH 9.0, temperature 34 °C, 140 mg SCN−/L and 205 mg CN−/L under which complete SCN− and CN− degradation would be achieved over a 168-h period. Using the optimised data, co-metabolism of SCN− and CN− by both E. acetylicum and B. marisflavi was evaluated, achieving a combined degradation efficiency of ≥99.9 %. The high degradative capacity of these organisms has resulted in their supplementation on an active continuous biological degradation system that is treating both SCN− and CN−.

2016-01-01T00:00:00Z Mekuto, Lukhanyo Ntwampe, Seteno Karabo Obed Utomi, Clement E Mobo, Mmabatho Mudumbi, John Baptist Nzukizi Ngongang, Maxwell Mewa Akinpelu, Enoch Akinbiyi http://hdl.handle.net/11189/5543 2020-08-12T12:26:33Z 2017-01-01T00:00:00Z

Title: Performance of a continuously stirred tank bioreactor system connected in series for the biodegradation of thiocyanate and free cyanide Authors: Mekuto, Lukhanyo; Ntwampe, Seteno Karabo Obed; Utomi, Clement E; Mobo, Mmabatho; Mudumbi, John Baptist Nzukizi; Ngongang, Maxwell Mewa; Akinpelu, Enoch Akinbiyi Abstract: A microbial consortium which was largely dominated by Thiobacillus sp. and Serratia sp. was evaluated for the biodegradation of thiocyanate (SCN−) and free cyanide (CN−) under neutral to alkaline conditions, in a two-staged stirred tank bioreactor system operated in series. The bioreactors were operated across a range of residence times (7 d to 24 h), SCN− (100–1000 mg SCN−/L) and CN− (200–450 mg CN−/L) concentrations at room temperature (21–25 °C). The bioreactors were characterised by high SCN− degradation efficiencies (>99.9%) throughout the experimental run except when the microorganisms were temporarily shocked by a pH increase and the introduction of CN− within the system. Similarly, high CN− biodegradation efficiencies (>99.9%) were observed subsequent to its introduction to the system. Planktonic microbial activity tests by organisms within the bioreactor system revealed high SCN− and CN− degradation efficiencies (>80%); a direct indication of high planktonic microbial activity within the bioreactor system. Furthermore, there was an observed total nitrogen removal by the organisms within the system, which demonstrated the nitrification and denitrification capacity of the organisms while the sulphate concentration increased as a result of SCN− biodegradation, over a period of approximately 300 days. This is the first report on the simultaneous biodegradation of high CN− and SCN− concentrations, coupled with nitrogen removal under alkaline conditions. The results demonstrated the potential of the process to treat CN− and SCN− laden wastewaters.

2017-01-01T00:00:00Z