Modeling for Prediction of Sludge Accumulation in Septic Tanks
Keywords:
Dynamic modelling, Sludge accumulation, Septic tank, Treatment performanceAbstract
Sludge accumulation in septic tanks usually affects the tank performance and is essential for planning of the sludge emptying frequency and treatment. Based on the laboratory-scale experimental results, material balance analysis of TS and TVS concentrations in the septic tank influent, effluent and accumulation was used to calculate the first-order rate constant of sludge reduction, which was found to be 0.004 d-1. To deal with complex mechanisms in the septic tanks, a dynamic model for sludge accumulation using STELLA software was developed by integrating key factors/equations that represented the septic tank performance. The model was validated by using data from the laboratory-scale septic tank and 8 units of actual-scale septic tanks of peri-urban households, resulting in the R2 values of 0.70 - 0.80 which suggested the applicability of the model in predicting the sludge accumulation in septic tanks. This model should be useful for the septic tank users and municipal officers in planning for emptying the accumulated sludge and creating a modelling platform for describing TS and TVS accumulation in the septic tanks.
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