Inactivation of Escherichia Coli, Coliforms and Coliphages During Storage of Animal Wastes Under Tropical Climatic Conditions

Abstract

Background: Animal waste management in the peri-urban and urban settings in the developing countries is hampered by the lack of proper handling of such wastes. The current methods of animal waste handling are based on common practices without considering the impact caused by such wastes in the public health. As a result such wastes are handled as other house garbage and disposed haphazardly in the environment including water bodies. This affects the quality of water for home consumption; contributing to air and environmental pollution and spread of enteropathogens to the public. Objective: Establishing suitable treatment method so as to increase the rate inactivation faecal indicator bacteria as model for management animal waste pathogens under the tropical conditions. Method: Cattle dung was treated basing on conventional heap (farmers practice), semi-aerated heap, semi-anaerobic heap, and modified (aerated) heap, where the dung was stored on a metal mesh, allowing free aeration from below and sides. Cattle waste indigenous E. coli, other coliforms and coliphages were enumerated as a function of treatment and time to determine the inactivation rate (T90). Result and conclusion: Temperature and pH values in heaps were measured on each day of sampling, while %DM values were calculated on day 0, 21 and 50. On average, coliphages declined more rapidly than E. coli and other coliforms in all treatments. The T90 values varied significantly between treatments (p < 0.001) for E. coli and other coliforms (p < 0.01), with the aerated heap as the most effective with regard to inactivation and the semi-anaerobic heap as the poorest. In contrast, there was no statistical significant difference in coliphage inactivation (p > 0.93) with respect to treatment. Storage of cattle waste on metal-mesh in the tropical climate allows optimal aeration resulting into improved inactivation of indicator bacteria. It is recommended that more studies are carried on involving typical farmers’ waste management practise, for the betterment of the environment and the public in general.