A study on mechanical lubricant wastewater treatment by carbonized rice husk

After carbonized at different temperatures, agricultural waste-rice-husk, becomes carbonized, which has further been modified at different pH values. Through some static tests, we studied the treatment efficiency for the wastewater-containing mechanical lubricants- by the carbonized rice husk at different amounts of carbonized rice husk, different treatment times and different processing temperatures. The results showed that the optimal carbonization temperature of the rice husk is around 500 °c, and the pH modification's impact was not notable. The optimal conditions of the treatment of wastewater containing 10% mechanical lubricant (volume percentage, made by Shell), were found at the amount of 6g/l carbonized rice husk, with the processing time of 15 min, and the temperature of 15 °c. Under that condition, the oil removal rate could reach 88.38% and adsorption capacity of the carbonized rice husk is 22.32ml/g; however, when referring to Mobil (model: 20W-40), the oil removal rate could reach 94.24%, which is considerably superior to other kinds adsorbents. Treatment of oily wastewater by carbonized rice husk is in conformity with the second order kinetic equation, and the related coefficient is 0.9671; besides, the adsorption thermodynamic analysis shows that the adsorption process can be spontaneous at the low temperature, which therefore can be used for the oily waste water treatment. © (2012) Trans Tech Publications, Switzerland.