Applications of the Ecoli Bacteria Model In Predicting Fecal Coliforms In Surface Runoff

Models are tools used by environmental managers for planning purposes. The ECOLI model is a tool developed for that purpose. The ECOLI model is a biological model capable of simulating continuously E. coli density on land and subsequently E. coli concentrations in surface runoff during rainfall events. This model can be used to predict the nonpoint source input of E. coli into the receiving water bodies.Since fecal coliform is a common water quality indicator and water quality standards are frequently based on fecal coliforms instead of E. coli, a fecal coliform prediction model would be extremely useful for the accounting of fecal coliforms input into the receiving waters. However, the applicability of the ECOLI model in simulating fecal coliform has yet to be verified. In this study, the ECOLI model predicted fecal coliform concentrations were compared with the fecal coliform data collectea from field studies conducted in the Agricultural Experimental Station in Louisiana,U.S.A. The result of the comparison indicated that the ECOLI model predicted the decay of the fecal coliform well following the first manure applications of 1996.However, there was an increase in departure from the observed fecal coliform concentrations following the second to the fourth manure applications. Possible causes of the difference between the predicted and observed concentration could be regrowth of fecal coliforms and the competitive advantage of the fecal coliforms in reapplied manure compared to fecal coliforms in the first-time applied manure. More studies need to be conducted to investigate the decay of fecal coliforms in soils reapplied with manure The ECOLI model can be applied for predicting fecal coliform concentrations in runoff in Malaysia if modifications are made and the model field-tested

Modelling of Escherichia coli Density on Land and Concentration in Surface Runoff

Integrated fanning of crop and animal enables (eSources from animal waste to be utilised. However, bacterial pollution is a concern.In this study, a bacterial model,ECOLI, was developed to simulate Escherichia coli density daily on land and its concentration in surface runoff. Loss of E. coli was assumed to occur through decay,runoff, sediment and percolation. E. coli decay was assumed to follow the first order decay affected by soil pH, soil. tempcirature and soil moisture.In testing the model, the ECOLI model was interfaced with the GLEAMS-SWT hydrologic and erosion model. Calibration and evaluation was performed with field-scale data from Franklinton, Louisiana. Fresh cow manure· was applied on grassed plots and runoff was collected and analysed. Predicted E.coli concerntrations versus observed E. coli centrations in surface runoff gave a regression line with coefficient of determination of 0.993, intercept of 0.011 and a slope of 0.995 indicating good agreement of model predicted conCentrations with observed concentrations. The ECOLI model can be used to study die effects of various animal waste application practices such as waste loading rate, timing of application and frequency of application. More research needs to be conducted to incorporate databases so as to expand the capabilities of this model