Escherichia coli strains harvested from springs in Kampala, Uganda: cell characterization and transport in saturated porous media

Abstract

We hypothesized that the transport of Escherichia coli strains harvested from springs could be characterized by a similar set of cell characteristics and transport parameters. The hypothesis was tested by sampling springs throughout the Lubigi catchment in Kampala, Uganda. Chemo‐physical parameters in addition to total coliform concentrations were determined. Furthermore, E. coli strains were harvested, and cell properties determined. Column experiments in saturated quartz columns of 7 cm height were conducted to determine transport parameters of selected E. coli strains. Using a two‐site non‐equilibrium sorption model, transport was modelled by fitting breakthrough data in HYDRUS 1D. Results indicated faecal contamination of the springs with high concentrations of total coliforms, chloride and nitrate. Furthermore, the maximum relative E. coli concentrations (C/C0)max in the column experiments were high. Compared with our previous work on E. coli strains, collected from a pasture and from zoo animals, attachment was low. Modelling revealed that both equilibrium and kinetic sorption were not important under conditions employed in the experiments. These observations are explained by the way in which the strains were harvested: from termination points of flow lines (springs). Such strains may possess characteristics that might have influenced their transport in the subsurface leading to their low attachment efficiency and possibly contributing to the lack of influence of equilibrium and kinetic sorption characteristics. There was no significant correlation between cell properties and transport parameters. Furthermore, 58% of the tested strains were of the O21:H7 serotype, and all definable serotypes identified were associated with diseases. We speculate that this serotype may possess characteristics that allow preferential transport through the aquifers of the area. We demonstrated that bacteria harvested from termination points of flow lines compared with those obtained from pollution sources, which have not undergone transport yet, present a good option for the assessment of bacteria transport characteristics in aquifers. Copyright © 2013 John Wiley & Sons, Ltd.

Microbial Groundwater Quality Status of Hand-Dug Wells and Boreholes in the Dodowa Area of Ghana

“…Hand-dug wells have variously been implicated with microbial contamination of groundwater sources [ 7 ]. Results of contamination risk assessment indicated that the shallow hand-dug wells in the area have more sanitary issues that can cause pollution compared to the boreholes ( Table 1 ).…”

“…Evidence from previous studies in different countries within the Sub-Saharan Africa region shows that groundwater sources; boreholes [ 1 , 5 , 6 ], springs [ 2 , 7 ] and hand-dug wells [ 8 ] may be polluted with microbial pathogens originating from the intestinal tract of humans and warm blooded animals. The link of improper on-site sanitation facilities in poor urban and rural areas to groundwater pollution is common in the literature [ 4 , 9 , 10 , 11 , 12 ].…”

Groundwater pollution assessment in a coastal aquifer in Cape Coast, Ghana

“…Bacteriological water quality assessment followed previously used methods [32]. To do this, 100 mL of water sample from hand dug wells was collected in sterile polypropylene bottles and pressed through an 0.45μm cellulose acetate filter paper by means of a syringe.…”

Socio-Institutional Drivers of Groundwater Contamination Hazards: The Case of On-Site Sanitation in the Bwaise Informal Settlement, Kampala, Uganda

“…However, globally, over 1.7 billion people depend upon groundwater resources threatened by increasing contamination and depletion [1]. Groundwater contamination hazards include microbial, chemical, and, more recently, micropollutants of emerging concern [2][3][4]. Microbial pathogen contamination, including bacteria, viruses, protozoa, and helminths, have been most prevalently reported, especially in the developing world where inadequate sanitary practices prevail [3,5].…”

“…Groundwater contamination hazards include microbial, chemical, and, more recently, micropollutants of emerging concern [2][3][4]. Microbial pathogen contamination, including bacteria, viruses, protozoa, and helminths, have been most prevalently reported, especially in the developing world where inadequate sanitary practices prevail [3,5]. The increasing risk of groundwater contamination is a significant hindrance Water 2021, 13, 2153 2 of 17 to meeting the sustainable development goal (SDG) number 6, to ensure availability and sustainable management of water and sanitation for all [6].…”