Optimisation of cod removal from the effluent discharged by the wet corn processing industry in Western Cape

Abstract

This study was performed at a wet corn milling(WCM) plant in the Western Cape (WC). It explores the application of Six-Sigma DMAIC to develop a procedure for reducing the carbon oxygen demand (COD) concentrations in the WCM effluent, using the scientific approach – adsorption coconut granular activated (CGAC) method – relevant quality tools and quality techniques. The research method followed a structured Six Sigma DMAIC framework for primarily investigating the root causes of non-conforming COD concentrations in the effluent generated by the WCM plant. Thereafter, it seeking a suitable procedure to improve the current management of the COD concentrations by the WCM plant to consistently adhere to the legislated COD concentrations requirement. The data used in this research was collected by means of quantitative laboratory experiments. Where, trial one experiments used 36 acidic samples, and trial two used 36 alkaline samples. The data was interpreted and analysed using statistical tests. The validity of the data was assured by means of applying reference standards and repeated measurements under different environmental conditions. The findings indicated that there was a gap in the current control measuring system used to ensure that the effluent was free of product cross-contamination. This research also found that the current procedures used for addressing the management of non-conforming of COD concentrations were not effective. Furthermore, the current COD detection system was found to be working, but not effectively enough; therefore, urgent continuous improvement is required to better its performance output. This study recommends that an additional process step is required for treating the non-conforming COD concentrations to comply with the legislated COD standard requirement. Moreover, improvement is required in the skills development of the process owners to better monitoring of the interlinked processes. The current COD detection system requires improvement to enhance its performance.