Bacteriological and Physicochemical Analysis of Groundwater in Selected Communities in Obio Akpor, Rivers State, Nigeria

Abstract

Aim: This research work is aimed at assessing the quality of groundwater in Rumuekini, Rumuosi, Aluu communities in Obio-Akpor, Rivers State, Nigeria. Methodology: Bacteriological and physicochemical analyses were carried out on selected borehole water in Obio-akpor local government area, Rivers state and its environs. Twenty seven samples were obtained randomly from the following locations/communities namely: Rumuekini (nine samples), Rumuosi (nine samples) and Aluu (nine samples). In the study, total heterotrophic bacteria and coliforms were enumerated using the membrane filtration and multiple tube fermentation methods, respectively. The isolates were identified based on cultural, morphological characteristics and a battery of biochemical tests. Selected samples were also subjected to physicochemical analysis of parameters like pH and electrical conductivity which were measured in situ using the pH meter and the conductivity meter respectively. The temperature of the samples was also measured in situ using a thermometer. The nitrate, sulphate and chloride content of the samples were determined using the spectrophotometric and argentometric methods respectively. Biological Oxygen Demand and Chemical Oxygen Demand were measured using the Winkler (respirometric) and titrimetric methods respectively; while the heavy metals’ content of the samples were determined using the atomic absorption spectrophotometer. Results: In this study, the total heterotrophic bacteria count for the samples ranged from 0.02 to 2.74 x 102cfu/ml and were quite high compared to E.P.A and W.H.O standards of 1.0 x 102 cfu/ml for total heterotrophic bacteria. The results obtained from this study showed that coliform bacteria were present in forty percent of the samples analysed with counts ranging from 0MPN/100 ml to 9.1 MPN/100 ml. These values were much higher than the W.H.O. standards of zero coliform/100 ml. Enterobacter aerogenes was the most common coliform isolated while Escherichia coli was isolated from only one of samples obtained from Aluu community. Pathogens like Salmonella and Vibrio were not detected in any of the samples. The physicochemical analysis of borehole water samples obtained from the three locations revealed the following range values: pH (5.8-7.5), temperature (25-29ºC), turbidity (0-0.8 NTU), Nitrate (1.32-7.72 mg/l), Sulphate (0.43-14.8 mg/l), B.O.D (1.8-4.4) etc. The concentration of zinc in the sampling locations ranged from 0.01 to 0.34 mg/l while that of lead and iron ranged from 0.01 to 0.06 and 0.03 to 0.25 mg/l respectively. Conclusion: The investigation in this study suggests that the borehole water samples were within W.H.O specified limits for the physicochemical parameters apart from pH that is below limit (5.8) for one of the samples obtained from Rumuekini; The status of water in some of these locations using microbiological, and physicochemical parameters as indicators can be said to be of acceptable limit for human consumption. However, the results obtained from this study showed that forty percent of the samples analysed had total coliforms (i.e. do not confirm with W.H.O standards); this may be as a result of improper construction/drilling of the boreholes or contamination of the storage tanks. There is need for the treatment of water from some of these boreholes in order to reduce the risk of infection.