Adsorption of residual oil from oily wastewater using natural adsorbents

Abstract

Pollution of water due to oil contamination is a major environmental problem. This study focuses on the removal of emulsified oil from oily wastewater. Generally emulsified oil is treated using chemicals and therefore it causes series of problems. In this study, oil adsorption capacity of thermally treated rice husk prepared by carbonizing rice husk at 600 °C for 3 hours was tested. Batch experiments were conducted to determine the optimum value of process parameters. Adsorbent dosage, initial oil concentration, solution pH and adsorbent size affect the oil removal capacity. Oil removal was measured by the percentage of COD reduction. The experiments revealed that the optimum particle size range of carbonized rice husk for oil treating was 605~m.The adsorbent to solution ratio affects the degree of oil removal and percentage COD reduction of 40 and 100 were observed with 0.5g and 109 of adsorbent dose per litre of wastewater respectively. Kinetic data tend to fit well in second order kinetics and the Langmuir isotherm best represent the adsorption of oil onto carbonised rice husk. Monolayer oil adsorption capacity of 2.24mg of oil / g of carbonised rice husk was observed.