Identification and enumeration of microbial organisms in grey water in the Khayelitsha informal settlement, Western Cape, South Africa

Abstract

Grey water, as opposed to blackwater, is generally assumed to be a safer and more acceptable wastewater source that could be considered for reuse. This is mainly due to a common misconception that its microbial load is lower compared to that of blackwater (domestic sewage). This study aimed to determine the presence of microbial contaminants, specifically pathogens, in stagnant greywater in the RR Section in Khayelitsha,Western Cape. Themost probable number (MPN) techniquewas conducted to determine faecal coliform (FC) and Escherichia coli (EC) counts in the samples. The API 20E and the RapID ONE systems were used to identify possible pathogenic Gram-negative microorganisms, while the isolated Gram-positive microorganisms were identified using the BBL Crystal Gram-Positive (GP) Identification (ID) system. The highest respective FC and EC counts observed during this period were recorded as 2.8 × 107 microorganisms/100 mL (Site F, week 5). The RapID ONE and the API 20 identification systems identified mostly Escherichia coli, Klebsiella species and Enterobacter cloacae, amongst others, while the BBL Crystal-GP ID system identified mostly Corynebacterium and Bacillus species. The presence of these organisms raises health concerns for the community of RR Section.