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Articles by M.N.B. Momba
Total Records ( 7 ) for M.N.B. Momba
  O.B. Akpor , M.N.B. Momba and J. Okonkwo
  This study was aimed at investigating the effect of nine different nutrient/carbon supplements in mixed liquor on nutrient uptake ability of three wastewater protozoan isolates, which have previously been screened for phosphate and nitrate uptake efficiency. The results revealed that over 50% of phosphate was removed in the presence of sodium acetate, glucose or sucrose. Similarly, nitrate uptake of over 60% was observed in the presence of sodium acetate, sodium succinate, glucose or sucrose. These trends were common in all the isolates. Chemical Oxygen Demand (COD) removal in the mixed liquor was only found to be significantly removed in mixed liquors that were supplemented with glucose, sucrose or sodium succinate. In the presence of sodium acetate, COD was observed to increase. The findings of this investigation have revealed that nutrient uptake and COD removal by the test protozoan isolates may be dependent primarily on the initial nutrient supplement in mixed liquor.
  M. Sibewu , M.N.B. Momba and A.L. Okoh
  This study focuses on the assessment of the protozoan fauna and abundance in the mixed liquors of aeration tanks of the three municipal wastewater treatment plants located in Fort Beaufort, Dimbaza and East London in the Eastern Cape Province of South Africa and their implication to the production of effluents of good quality. The samples were collected between September and December 2005 and protozoa species were identified by direct microscopic observations at x400 magnification by comparison with existing protozoa gallery collections. A total of 68 protozoan genera made up of 44 ciliates, 16 flagellates and 8 others were identified in wastewater treatment plants. Although in all aerobic zones the average density of ciliates was 104 cells mL-1, which indicated that these plants were able to produce clear effluent of good quality, a better performance was found in Dimbaza and East London, which had total protozoan genera of 27 and 26, respectively.
  B.O. Abong`o , M.N.B. Momba and N. Rodda
  The current study explored the health risk of E. coli O157:H7 to diarrhoeic confirmed and non-confirmed HIV/AIDS patients due to their exposure to presumed ingestion of water, meat products and vegetables ostensibly contaminated with E. coli O157:H7. Strains of E. coli O157:H7 were isolated by enrichment culture and on Cefixime-Telurite Sorbitol MacConkey agar. Average counts of presumptive E. coli O157 were used for dose-response assessment. Probability of infection to confirmed and non-confirmed HIV/AIDS patients was 20 and 27% from meat and meat products, 21% and 15% from vegetables and 100% due to ingestion of 1500 mL person-1 day-1 of water. Drinking water had higher probability of transmitting E. coli O157:H7 infections than meat and meat products and vegetables. Probability of E. coli O157:H7 infections were high for confirmed HIV/AIDS patients than for non-confirmed patients. Water and foods consumed by HIV/AIDS patients should be safe of any microbial contaminants, these waters and foods should as well be investigated for other enteric pathogens to establish their safety.
  B.O. Abong`o , M.N.B. Momba , V.K. Malakate and J.N. Mwambakana
  This study investigated the prevalence of Escherichia coli O157:H7 in the stool of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Escherichia coli O157:H7 was isolated by culture-based and immunomagnetic separation from three hundred and sixty stool swabs. Identification was by conventional IMViC, 20E API and molecular techniques. Confirmed and non-confirmed diarrhoeic HIV/AIDS patients had 56.5% (74/131) and 43.5% (57/131) respectively of E. coli O157:H7. Molecular results indicated that the prevalence of E. coli O157:H7 was 12.16% (9/74) and 8.77% (5/57) from stool swabs of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Antimicrobial resistance was higher for E. coli O157:H7 isolates from stools of confirmed HIV/AIDS than it was for non-confirmed HIV/AIDS patients. Escherichia coli O157:H7 might be a silent cause of diarrhoea in HIV/AIDS patients. It is recommended that HIV/AIDS patients with diarrhoea should be screened for E. coli O157:H7 and surveillance programmes for these bacteria should be established in both urban and rural areas of South Africa.
  O.B. Akpor , M.N.B. Momba and J. Okonkwo
  In the present study, the efficiency of ten selected wastewater protozoa in the removal of phosphorus and nitrogen and their effects on other physico-chemical parameters was investigated. Protozoa were isolated from the aerobic zone of Daasport wastewater treatment plant, in Pretoria, South Africa, using the modified Chalkey’s medium. The isolates were screened for nutrient removal ability in shake flasks, at laboratory temperatures for 96 h. During each sampling, aliquot samples were collected for the analysis of phosphorus, nitrate-nitrogen, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), pH, of the mixed liquor including the growth rate of the isolates using standard methods. The results indicated a steady increase in growth rate of the isolates and all the isolates used in this study showed some measure of phosphorus and nitrate removal ability. In the presence of the test protozoa isolates, an increase in COD and a decrease in DO were noted in the mixed liquor inoculated with the organisms, while the pH only increases slightly. This study revealed a significant correlation between growth rate and nutrient removal (R = -0.806, p<0.001 for phosphorus; R = -0.799, p<0.01 for nitrate). The present study has been able to show that certain protozoa isolates have the ability to biologically remove phosphorus and nitrate from effluent. Consequently, it would be necessary to identify what strains of protozoa are capable of excess phosphorus and nitrogen uptake for the treatment of wastewater.
  O.B. Akpor , M.N.B. Momba and J.O. Okonkwo
  The present study was aimed at investigating the relationship between carbon source concentration and nutrient uptake efficiency of three protozoan isolates. Three carbon sources (acetate, glucose and sucrose) were used at respective concentrations of 5, 10 and 15 g L-1 for this investigation. The study was carried out in a shake flask at a temperature of 25°C. Aliquot samples were collected at time zero and every 24 h for the estimation of phosphate, nitrate, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO) and growth rate. Results revealed a significant phosphate and nitrate uptake at carbon source concentration of 5 g L-1. This was irrespective of isolates or carbon source used. The results also showed that with a high initial carbon source concentration, initial COD was observed to be high. In the presence of acetate, COD removal from mixed liquor was not observed. However in the presence of glucose or sucrose, COD decrease was observed. There was no observed significant variation (p<=0.05) between DO values at the different concentrations of carbon source. A similar trend was also observed for growth rate. This study had been able to give an insight into the optimum carbon source concentration in mixed liquor that will enhance nutrient uptake by the test protozoa.
  A. Okeyo , M.N.B. Momba and M. Coetzee
  The Hazard Analysis and Critical Control Points (HACCP) concept was used in the present study to identify any potential process failures in the Temba, Klipdrift and Wallmansthal water treatment plants. Water samples were collected at various critical points: raw water, after sedimentation, after filtration, after chlorination and at the Point of Use (POU). Turbidity, pH, temperature, chlorine residual and indicator bacteria (total and faecal coliforms) were measured using standard methods. On average, results revealed that pH and temperature conformed to the limits allowed by the National Standards. The average percentage removal of turbidity was from 41.1 to 80.5% after sedimentation and from 75.1 to 97.8% after filtration. At the Point of Treatment (POT) and POU, the turbidity ranged from 0.3 to 1.1 NTU and from 0.4 to 1.4 NTU, respectively. The concentration of chlorine residual in these two critical points ranged from 1.9 to 2.3 mg L-1 and from 0.3 to 0.6 mg L-1, respectively. The average percentage removal for indicator bacteria ranged from 35.8 to 86.1% after sedimentation, from 74.2 to 97.3% after filtration and from 99.6 to 100% after chlorination. The failure of the pre-treatment stages and the chlorination process to remove potential pathogenic bacteria such as Aeromonas and Pseudomonas sp. resulted in the presence of these microorganisms at the POU. Efforts should be focused on the pre-disinfection stages to deliver a low microbial load that chlorine may be able to handle.
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