Assessment of Coliforms Bacteria Contaminant in Nkenye Stream in Meru South, Kenya

Abstract

Access to portable water remains a major global concern due to increased rate of water pollution contributed to by human pressure such as accelerated urbanization, high population, industrialization and intense agricultural activities that destroy riparian zones thus exposing the rivers and streams to toxic and pathogenic pollutants released from untreated organic and inorganic waste. Exposure of river and stream used for drinking water to pollution is detrimental to both aquatic plants, human consumers and animals inhabiting water bodies. Nkenye stream in Meru South is depended upon for supplying water to fish ponds constructed along it, irrigation and domestic use to the neighboring homesteads. However, little attention has been paid to ascertain the quality of its water despite the stream being located in an urban area with high exposure to pollutants. Pressure on Nkenye wetlands ecosystem that supply water to Nkenye stream has seen major destruction of riparian leaving zones just few plant communities such as Commelina banghalensis whose water purification potential is not well known. Based on the above fact, a study was conducted to determine water quality of Nkenye stream based on the presence of feacal and total coliform. Samples were collected at designated locations using ecological survey method and taken to Chuka university for evaluation. Coliform analysis of water samples was done by most probably number method using Macconkey purple broth at botany laboratory, Chuka University. Results were analyzed by General linear model (GLM) on Statistical analysis system (SAS) version 9.4 and significance means separated by Least significance difference (LSD) [alpha = 0.05]. Faecal coliform were found not to conform with WHO standards of 0 cfu/100 ml as the mean of 10 cfu/100 ml was observed for the entire stream. Occurrence of these bacteria in water indicate water deterioration and presence of many water-borne pathogens that needs immediate attention. Considerable amount of chemical was observed in the root samples of Commelina banghalensis showing that the plant can be utilized in removal of chemicals in the stream. It is recommended that local authorities particularly Tharaka Nithi county government should provide waste management disposal systems and policies that prohibit direct discharge of untreated effluents to the stream.