Sewage reuse for irrigation in Athi River town: its implications on public health

Abstract

Lead, cadmium, selenium and arsenic were the selected indicators of toxic heavy metals which were determined using atomic absorption spectroscopy (AAS) in sewage being reused for irrigation in Athi River town of Kenya. Coliform counts and Escherichia coli were also determined in the same sewage as indicators of pathogenic bacterial agents. Lead and cadmium were further detected in soils and in a selected number of food crops under sewage irrigation. The pH of both soils and sewage was also tested as the main factor that determine the availability of these toxic heavy metals to the crops. Similarly, the activities of the pathogenic microbiological agents were deduced with respect to the temperatures of the sewage. In general, an average of twenty samples per parameter were taken. The levels of toxic heavy metals were found as follows: lead (0.17 ppm), cadmium (0.04 ppm), selenium (0.009 ppm) and …