COD and Nutrient Removal Kinetics of Piggery Wastewater in Nigeria

Waste stabilisation ponds (WSPs) have been employed in treatment of diverse kinds of wastewater over the years. This system’s dynamics have been poorly understood and this has led to diverse problems over time such as reduced efficiency of reactors. This study employed the use of four models in the study of biological reaction in removal of organic matter from the waste stabilisation ponds. Prediction of removal rates of piggery wastewater in the ponds and at different retention times were studied using first order model, Monod, Grau and the Stover Kincannon model by fitting model to experimental data. Adaptability of the Monod model was poor in the anaerobic and part of the facultative pond. Monod model showed extent of substrate utilization by the cell yield coefficient ‘Y’ while the Stover Kincannon model’s maximum utilization rate constant (μmax) increased with increase in retention time. Stover Kincannon model showed a better adaptability (R2) than first and Monod models. Although the adaptability of first order was very poor, incremental biodegradation with time was noted which agrees with other models. Grau model gives a better system adaptation and agrees with other model substrate degradation prediction and also it best predicts efficiency of removal of substrate.