Quality indices of the final effluents of two sub-urban-based wastewater treatment plants in Amathole District Municipality in the Eastern Cape Province of South Africa
- Authors: Gcilitshana, Onele
- Date: 2014
- Subjects: Whole effluent toxicity testing -- South Africa -- Eastern Cape , Sewage disposal plants -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape , Effluent quality -- Testing , Viruses -- South Africa -- Eastern Cape , Water reuse -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11288 , http://hdl.handle.net/10353/d1019816 , Whole effluent toxicity testing -- South Africa -- Eastern Cape , Sewage disposal plants -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape , Effluent quality -- Testing , Viruses -- South Africa -- Eastern Cape , Water reuse -- South Africa -- Eastern Cape
- Description: Worldwide, water reuse is promoted as an alternative for water scarcity, however, wastewater effluents have been reported as possible contaminants to surface water. The failure of some wastewater treatment processes to completely remove organic matter and some pathogenic microorganisms allows them to initiate infections. This manifests more in communities where surface water is used directly for drinking. To assess water quality, bacteria alone cannot be used as it may be absent in virus-contaminated water. This study was carried out to assess the quality of two wastewater treatment plant effluents from the Eastern Cape Province of South Africa. Physicochemical parameters and microbiological parameters like faecal coliforms, adenovirus, rotavirus, hepatitis A virus, norovirus and enterovirus were evaluated over a projected period of one year. Physicochemical parameters were measured on site using multiparameters, faecal coliforms enumerated using culture-based methods and viruses are detected using both conventional and real-time PCR. Physicochemical parameters like electrical conductivity, turbidity, free chlorine and phosphates were incompliant with the standards set by the Department of Water affairs for effluents to be discharged. Faecal coliform counts were nil for one plant (WWTP-R) where they correlated inversely (P < 0.01) with the high free chlorine. For WWTP-K, faecal coliforms were detected in 27% of samples in the range of 9.9 × 101 to 6.4× 104 CFU/100ml. From the five viruses assessed, three viruses were detected with Rotavirus being the most abundant (0-2034176 genome copies/L) followed by Adenovirus (0–275 genome copies/L) then Hepatitis A virus (0–71 genome copies/L) in the WWTP-K while none of the viruses was detected in WWTP-R. Species B, species C and Adv41 serotypes were detected from the May 2013 and June 2013 samples where almost all parameters were incompliant in the plant. The detection of these viruses in supposedly treated effluents is suggestive of these being the sources of contamination to surface water and therefore renders surface waters unsafe for direct use and to aquatic life. Although real-time PCR is more sensitive and reliable in detection of viruses, use of cell-culture techniques in this study would have been more efficient in confirming the infectivity of the viruses detected, hence the recommendation of these techniques in future projects of this nature.
- Full Text:
- Date Issued: 2014
- Authors: Gcilitshana, Onele
- Date: 2014
- Subjects: Whole effluent toxicity testing -- South Africa -- Eastern Cape , Sewage disposal plants -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape , Effluent quality -- Testing , Viruses -- South Africa -- Eastern Cape , Water reuse -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11288 , http://hdl.handle.net/10353/d1019816 , Whole effluent toxicity testing -- South Africa -- Eastern Cape , Sewage disposal plants -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape , Effluent quality -- Testing , Viruses -- South Africa -- Eastern Cape , Water reuse -- South Africa -- Eastern Cape
- Description: Worldwide, water reuse is promoted as an alternative for water scarcity, however, wastewater effluents have been reported as possible contaminants to surface water. The failure of some wastewater treatment processes to completely remove organic matter and some pathogenic microorganisms allows them to initiate infections. This manifests more in communities where surface water is used directly for drinking. To assess water quality, bacteria alone cannot be used as it may be absent in virus-contaminated water. This study was carried out to assess the quality of two wastewater treatment plant effluents from the Eastern Cape Province of South Africa. Physicochemical parameters and microbiological parameters like faecal coliforms, adenovirus, rotavirus, hepatitis A virus, norovirus and enterovirus were evaluated over a projected period of one year. Physicochemical parameters were measured on site using multiparameters, faecal coliforms enumerated using culture-based methods and viruses are detected using both conventional and real-time PCR. Physicochemical parameters like electrical conductivity, turbidity, free chlorine and phosphates were incompliant with the standards set by the Department of Water affairs for effluents to be discharged. Faecal coliform counts were nil for one plant (WWTP-R) where they correlated inversely (P < 0.01) with the high free chlorine. For WWTP-K, faecal coliforms were detected in 27% of samples in the range of 9.9 × 101 to 6.4× 104 CFU/100ml. From the five viruses assessed, three viruses were detected with Rotavirus being the most abundant (0-2034176 genome copies/L) followed by Adenovirus (0–275 genome copies/L) then Hepatitis A virus (0–71 genome copies/L) in the WWTP-K while none of the viruses was detected in WWTP-R. Species B, species C and Adv41 serotypes were detected from the May 2013 and June 2013 samples where almost all parameters were incompliant in the plant. The detection of these viruses in supposedly treated effluents is suggestive of these being the sources of contamination to surface water and therefore renders surface waters unsafe for direct use and to aquatic life. Although real-time PCR is more sensitive and reliable in detection of viruses, use of cell-culture techniques in this study would have been more efficient in confirming the infectivity of the viruses detected, hence the recommendation of these techniques in future projects of this nature.
- Full Text:
- Date Issued: 2014
Prevalence of listeria pathogens in effluents of some wastewater treatment facilities in the Eastern Cape province of South Africa
- Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape , Sewage -- Purification -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11264 , http://hdl.handle.net/10353/246 , Listeria -- South Africa -- Eastern Cape , Sewage -- Purification -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Wastewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community. Prevalence of Listeria in terms of total counts was 100 percent across all sampled locations. Free-living Listeria species showed prevalence ranging from 84-96 percent across the sampling locations; while Listeria species attached to large (180 μm) planktons exhibited prevalence ranging from 75 percent to 90 percent. The prevalence of medium-sized (60 μm) plankton associated Listeria species varied between 58 percent and 92.5 percent; whereas those of Listeria species attached to small (20 μm) planktons ranged from 65-100 percent across all three communities. Listeria prevalence was generally a reflection of the turbidity of the water system, with free-living Listeria species being more prevalent than plankton associated cells in the relatively less turbid rural and urban waters compared to the more turbid peri-urban waters where plankton attached cells were more prevalent in comparison with their free living counterparts The final treated effluent quality fell short of recommended standards for turbidity, chemical oxygen demand and phosphate across all three communities. In addition, the final effluent of the rural treatment plant also fell short of recommended standard for NO3, while that of the urban treatment plant did not comply with acceptable limits for dissolved oxygen and nitrite. Other physicochemical parameters were compliant with set standards after treatment. An inverse relationship was observed between chlorine residual and listerial density across the sampled facilities; the effect of chlorine was however not enough to eliminate the pathogen from the water systems. At the urban treatment plant and its receiving watershed, pH, temperature, EC, turbidity, TDS, DO, and nitrate varied significantly with season and sampling point (P < 0.05; P < 0.01). Salinity also varied significantly with sampling point (P < 0.01), while COD and nitrite varied significantly with season (P < 0.05). Although, the treated effluent fell within recommended water quality standard for pH, TDS, nitrate and nitrite, it fell short of stipulated standards for other parameters. Whereas the microbial quality of the secondary treated effluent at this (urban) facility fell short of recommended standard after secondary treatment, its physicochemical quality were generally compliant with recommended standards for reuse wastewater in agriculture and aquaculture. Listeria pathogens isolated from effluents of the rural wastewater facility were sensitive to 11 (55 percent) of the 20 test antibiotics, and showed varying (7-71 percent) levels of resistance to 8 antibiotics; whereas those isolated from the peri-urban community showed sensitivity to 6 (30 percent) of the 20 test antibiotics, and varying (6-94 percent) levels of resistance to 12 antibiotics; while the urban effluent isolates were sensitive to 3 (15 percent) of the 20 test antibiotics, and showed varying (4.5-91 percent) levels of resistance to 17 antibiotics. Multiple antibiotic resistances involving 78.5-100 percent of isolates and antibiotics combination ranging from 2-10 antibiotics was observed across the sampled locations. Penicillin G and ampicillin showed remarkably high (64-91 percent) phenotypic resistance across the three sampled facilities. Other antibiotics, to which isolates showed significant resistance, were linezolid (22-88 percent); erythromycin (43-94 percent) and sulphamethoxazole (7-94 percent). Two of the 14 Listeria strains isolated from the rural effluents were positive for ereA and sul1 antibiotic resistance genes; while sulII genes were detected in five of the 23 Listeria isolates from the urban effluent and none was detected in isolates from the peri-urban community. The presence of antimicrobial resistance genes in the isolates did not correlate with phenotypic antibiotic resistance. The current study demonstrated that Listeria pathogens easily survived the activated sludge treatment process as free-living and plankton attached entities and suggests that municipal wastewater treatment plants are a significant source of multiple resistant Listeria pathogens in the South African aquatic milieu. While the physicochemical quality of the urban final effluent suggests that it is a major source of pollution to the receiving watershed, the secondary effluent quality demonstrated a great potential for use in agriculture and aquaculture.
- Full Text:
- Date Issued: 2010
- Authors: Odjadjare, Emmanuel Erufuare Onogwuwhenya
- Date: 2010
- Subjects: Listeria -- South Africa -- Eastern Cape , Sewage -- Purification -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11264 , http://hdl.handle.net/10353/246 , Listeria -- South Africa -- Eastern Cape , Sewage -- Purification -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Wastewater discharges may contain health compromising pathogens and carcinogenic and/or chemical substances that could compromise the public health and impact negatively on the environment. The present study was conducted between August 2007 and July 2008 to evaluate the Listeria abundance (as free-living and plankton associated species) and physicochemical qualities of the final effluents of three wastewater treatment facilities in the Eastern Cape Province of South Africa selected to represent typical urban, peri-urban and rural communities and the impact of the discharged final effluents on their respective receiving watershed, as well as to elucidated the in vitro antibiotic susceptibilities and resistance genes profile of Listeria species isolated from the final effluents. The suitability of the secondary effluent of the urban treatment facility (as a case study) for use in agriculture and aquaculture with reference to recommended standards was also determined. Wastewater samples were collected from the raw sewage, secondary effluent, final treated effluent, discharge point, 500 m upstream discharge point, and 500 m downstream discharge point from all three locations on a monthly basis throughout the study period. Listeria abundance in the final effluents and the receiving watersheds varied between 2.9× 100 and 3.52 × 105cfu/ml across the sampled locations. Free-living listerial density across the sampled locations ranged between 0 and 3.2 × 103cfu/ml while counts of Listeria species attached to large (180 μm) planktons varied from 0 to 1.58 × 105 cfu/ml and those of the 60 and 20 μm categories were in the range of 0 to 1.32 × 103 cfu/ml and 0 to 2.82 × 105 cfu/ml respectively. Listeria abundance did not vary significantly with location and season; there was however, significant (P < 0.05; P < 0.01) variance in Listeria abundance with plankton sizes across the locations. Free-living Listeria species were more abundant in the rural and urban xii communities than plankton attached Listeria species; whereas the reverse was the case in the peri-urban community. Prevalence of Listeria in terms of total counts was 100 percent across all sampled locations. Free-living Listeria species showed prevalence ranging from 84-96 percent across the sampling locations; while Listeria species attached to large (180 μm) planktons exhibited prevalence ranging from 75 percent to 90 percent. The prevalence of medium-sized (60 μm) plankton associated Listeria species varied between 58 percent and 92.5 percent; whereas those of Listeria species attached to small (20 μm) planktons ranged from 65-100 percent across all three communities. Listeria prevalence was generally a reflection of the turbidity of the water system, with free-living Listeria species being more prevalent than plankton associated cells in the relatively less turbid rural and urban waters compared to the more turbid peri-urban waters where plankton attached cells were more prevalent in comparison with their free living counterparts The final treated effluent quality fell short of recommended standards for turbidity, chemical oxygen demand and phosphate across all three communities. In addition, the final effluent of the rural treatment plant also fell short of recommended standard for NO3, while that of the urban treatment plant did not comply with acceptable limits for dissolved oxygen and nitrite. Other physicochemical parameters were compliant with set standards after treatment. An inverse relationship was observed between chlorine residual and listerial density across the sampled facilities; the effect of chlorine was however not enough to eliminate the pathogen from the water systems. At the urban treatment plant and its receiving watershed, pH, temperature, EC, turbidity, TDS, DO, and nitrate varied significantly with season and sampling point (P < 0.05; P < 0.01). Salinity also varied significantly with sampling point (P < 0.01), while COD and nitrite varied significantly with season (P < 0.05). Although, the treated effluent fell within recommended water quality standard for pH, TDS, nitrate and nitrite, it fell short of stipulated standards for other parameters. Whereas the microbial quality of the secondary treated effluent at this (urban) facility fell short of recommended standard after secondary treatment, its physicochemical quality were generally compliant with recommended standards for reuse wastewater in agriculture and aquaculture. Listeria pathogens isolated from effluents of the rural wastewater facility were sensitive to 11 (55 percent) of the 20 test antibiotics, and showed varying (7-71 percent) levels of resistance to 8 antibiotics; whereas those isolated from the peri-urban community showed sensitivity to 6 (30 percent) of the 20 test antibiotics, and varying (6-94 percent) levels of resistance to 12 antibiotics; while the urban effluent isolates were sensitive to 3 (15 percent) of the 20 test antibiotics, and showed varying (4.5-91 percent) levels of resistance to 17 antibiotics. Multiple antibiotic resistances involving 78.5-100 percent of isolates and antibiotics combination ranging from 2-10 antibiotics was observed across the sampled locations. Penicillin G and ampicillin showed remarkably high (64-91 percent) phenotypic resistance across the three sampled facilities. Other antibiotics, to which isolates showed significant resistance, were linezolid (22-88 percent); erythromycin (43-94 percent) and sulphamethoxazole (7-94 percent). Two of the 14 Listeria strains isolated from the rural effluents were positive for ereA and sul1 antibiotic resistance genes; while sulII genes were detected in five of the 23 Listeria isolates from the urban effluent and none was detected in isolates from the peri-urban community. The presence of antimicrobial resistance genes in the isolates did not correlate with phenotypic antibiotic resistance. The current study demonstrated that Listeria pathogens easily survived the activated sludge treatment process as free-living and plankton attached entities and suggests that municipal wastewater treatment plants are a significant source of multiple resistant Listeria pathogens in the South African aquatic milieu. While the physicochemical quality of the urban final effluent suggests that it is a major source of pollution to the receiving watershed, the secondary effluent quality demonstrated a great potential for use in agriculture and aquaculture.
- Full Text:
- Date Issued: 2010
Surveillance of invasive vibro species in discharged aqueous efflents of wastewater treatment plants in the Eastern Cape province of South Africa
- Authors: Igbinosa, Etinosa Ogbomoede
- Date: 2010
- Subjects: Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11267 , http://hdl.handle.net/10353/245 , Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.
- Full Text:
- Date Issued: 2010
- Authors: Igbinosa, Etinosa Ogbomoede
- Date: 2010
- Subjects: Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11267 , http://hdl.handle.net/10353/245 , Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.
- Full Text:
- Date Issued: 2010
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