Faecal pollution loads in the wastewater effluents and receiving water bodies: a potential threat to the health of Sedibeng and Soshanguve communities, South Africa

Abstract

The discharge of untreated or inadequately treated effluents has been identified among the activities responsible for the spread of a wide range of potentially infectious agents. The aim of this study was to determine whether inadequate treatment of wastewater and the faecal pollution load of effluents and receiving water bodies in Sedibeng District and Soshanguve peri-urban area of the Tshwane Metropolitan Municipality could be a potential threat to the health of the surrounding communities. Variations in the counts of faecal indicator bacteria and pathogenic microorganisms and compliance of the effluents and receiving water bodies with South African and World Health Organization standards were assessed between August 2011 and May 2012 using culture-based methods and molecular techniques. The overall quality of effluents did not comply with the South African special standard of no risk for unrestricted irrigation (zero Escherichia coli/100 ml). The quality of the receiving water bodies did not comply with South African regulatory limits set for domestic purposes (zero E. coli/100 ml, <30 faecal enterococci/100 ml and <1 somatic coliphages/100 ml), for full contact recreation (<20 somatic coliphages/100 ml) and aquaculture (<10 E. coli/100 ml) and WHO standards for full and intermediate contact recreational use (<1 E. coli/100 ml and <40 faecal enterococci/100 ml, respectively). The PCR results revealed the prevalence of pathogenic microorganisms; between 0 and 60 % of samples tested positive for Salmonella Typhimurium and Shigella dysenteriae, and between 20 and 60% of samples tested positive for Vibrio cholerae. These findings demonstrated that potential health risks might be associated with the use of the target river waters for domestic, recreational and irrigation purposes. This study calls for a prompt intervention to improve wastewater management.

The Impact of Environmental Variables on Faecal Indicator Bacteria in the Betna River Basin, Bangladesh

“…The presence of indicator bacteria in waterbodies does not pose a direct risk of waterborne diseases, but their presence indicates faecal contamination and the possible presence of waterborne pathogens (Burres 2009;Teklehaimanot et al 2014). Risk of waterborne disease outbreaks also depends on water uses, such as consumption and recreational activities.…”

“…Although FIB are generally not harmful themselves, their presence in water body indicates the possible presence of other pathogenic microorganisms (Burres 2009). Indicators are useful in assessing health risk, regardless of whether the specific pathogens are pathogenic or not (Wu et al 2011;Teklehaimanot et al 2014). E. coli, faecal coliforms and faecal streptococci have been most commonly used as microbial indicators of faecal contamination in water bodies.…”

Vibrio cholerae and Cholera biotypes

“…These methods have high sensitivity, specificity, and speed. The methods used for V. cholerae detection by conventional PCR and/or real-time PCR are well established (Wang et al, 2007;Tebbs et al, 2011;Teklehaimanot et al, 2014). Many research studies have identified Vibrio cholerae strains using 16S rRNA sequencing, pulsed-field gel electrophoresis (PFGE), nested and multiplex PCR (Chakraborty et al, 1999;Kong et al, 2002;Tarr et al, 2007;Mendes et al, 2008;Keshav et al, 2010).…”

Chlorine Tolerance and Inactivation of Escherichia coli recovered from Wastewater Treatment Plants in the Eastern Cape, South Africa

“…In the study by [32] the tolerance of E. coli CGMCC to 10 mg/L chlorine dose was observed with only 4.0 log reduction achieved in a bacterial population of approximately 10 7 colony forming units (CFU/mL). In South Africa, studies have demonstrated a strong correlation between E. coli survival and low chlorine residuals [33][34][35]. For example, in the Eastern Cape, South Africa, [36] recovered E. coli strains in wastewater effluents containing low chlorine residuals ranged between 0.05 and 0.24 mg/L.…”