Abstract
Wastewater generated in white pepper (Piper nigrum L.) processing contains high Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and hydrolyzable tannins that results dark tan/brown colour effluent which cannot be discharged to the environment without proper treatment. Therefore, these experiments were conducted to investigate the effectiveness of electro-coagulation using aluminum (Al) electrodes and coagulation-flocculation with Alum [Al2(SO4)3.18H2O] in reducing the strength of pepper soaked effluent. A laboratory scale electro-coagulation unit was made using two aluminium plates (9 cm × 5 cm × 0.3 cm) as electrodes leaving a 0.5 cm gap between plates and powered with a 12 V DC power supply through a resistance box which is used to regulate the current density. The current density could be controlled between 0-1 A. Coagulation flocculation with Alum was tested at five doses; 1 to 5 g/L with 1 g increments at laboratory scale. The effluent colour was measured using a spectrophotometer at a wave length of 600 nm. According to the results, removal efficiencies of colour, Turbidity and COD were 94%, 91% and 89%, respectively for 20 minutes of electro-coagulation and 92%, 90% and 92%, respectively with 3 g/L Alum treatment. The pH of the effluent during electro-coagulation for 20 minutes increased to 9.0 while Alum treatment with 3g/L reduced to 5. When treated effluent filtered through a fine sand filter, Total Dissolved Solids (TDS), Electrical Conductivity (EC) and COD could be reduced further and reached the standard values to discharge in to the environment as irrigation water.