Colour and COD Removal from Food and Beverages Industrial Wastewater by using Spent Alkalis Carbide Lime (SACL)

The abundant amount of water used in the food & beverages (F&B) industry has caused the wastewater from this industry to be one of the major sources of water pollution, due to its high content of colour and chemical oxygen demand (COD). In this study, spent alkalis carbide lime (SACL) was used in treating the colour and COD simultaneously from the F&B industrial wastewater. SACL was used to reduce the amount of landfill waste and because of its similar characteristic to lime. The SACL was characterized using X-ray Diffractometer (XRD) X-ray Fluorescence (XRF), Scanning Electron Microscope (SEM), and Fourier-Transform Infrared Spectroscopy (FTIR) while the F&B industrial wastewater was characterized by using HACH DR6000 and UV-Vis Spectrophotometers. Several series of chemical precipitation experiments were conducted through jar tests to evaluate the effects of SACL dosing, pH value, and contact time on the percentage removal of colour and COD. The optimum conditions obtained from this study are pH 7 and 20 minutes, with percentage removal of 99.5% and 89.8% for colour and COD. However, the percentage removal of colour and COD decreased as contact time increased. With the same value of pH and contact time, SACL managed to remove more colours compared to lime, which is 93.6% compared to 88.54%, respectively. According to the analyses of FTIR and UV-Vis, the wastewater sample was cleaner when using SACL compared to using lime during the treatment. Thus, the study proves that SACL is a reliable alternative to treat colour and COD from F&B industrial wastewater.