Optimisation of waste stabilisation pond performance for piggery waste treatment using response surface methodology

Abstract

The treatment of piggery wastewater using the waste stabilisation pond was studied in a semi- continuous process. Optimisation of chemical oxygen demand (COD) removal was conducted using response surface me-thodology where pH, temperature and retention time were independent variables. The Box-Behnken design approach, an experimental design was used for creating a set of experimental runs needed for optimising COD removal. An attempt was also made to optimise COD removal by reducing hydraulic retention time while main¬taining pH and temperature of a defined range. Analysis of variance (ANOVA) was conducted on model terms and the results revealed that the coefficient of determination value (R2) of % COD removal was 0.86, 0.88, and 0.86 for the anaerobic, the facultative and the maturation pond, respectively. The highest desirability was ob¬tained for optimum COD % removal and this was 0.89, 0.89 and 1.0 for the ponds. The waste stabilisation pond treatment process can effectively be improved on for piggery wastewater treatment.