Enhanced sludge electrokinetic dewatering using pre-treatment techniques

• Main Author: Tien, Matthew Wei Xian
• Other Authors: Wang Jing-Yuan
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/61225
• Institution: Nanyang Technological University

Electrokinetic process has increasingly being recognised globally as an efficient and low cost alternative to sludge dewatering. It is a process of applying electric field to increase liquid/solids separation and hence enhance dewatering efficiency. Although numerous studies have validated the use of sludge pre-treatment techniques to enhance electrokinetic dewatering, the effects of pre-treatment on the sludge physico-chemical properties and its dewatering capability were not well discussed. Limited researches have also being done to explore the sludge energy content and combustion behaviour after electrokinetic process. In this study, the effects of Freeze Thaw, Ultrasound and pH adjustment as pre-treatment techniques on the dewatering capability and physico-chemical properties of sludge were explored. In addition, the effects of the pre-treatment techniques on the sludge organic matter, energy content and the combustion behaviour at different segment of the final sludge cake were investigated. Experiments were carried out using different applied potential gradient of 20V/20cm, 20V/10cm, 10V/20cm and 10V/10cm. Sludge collected from Ulu Pandan Wastewater reclamation plant underwent 2 rounds of centrifuge to reduce the moisture content to about 92.0-93.5%. Following the mechanical dewatering, sludge was pre-treated by freeze thaw, ultrasound and pH adjustment before loading into the reactors. Final sludge cake and filtrate obtained underwent further analysis. Results showed that Ultrasound pre-treatment was most desirable with increased dewatering capability and low energy consumption. pH adjustment at 4.5 yielded heightened dewatering capabilities, while pH adjustment at pH 1.5 and 10.5 reversed electroosmosis flow. Higher sludge energy content was observed in the anode region as a result of the higher measured organic content. The sludge at the cathode segment recorded higher ignition temperature and lower maximum rate of combustion. In conclusion, this study suggests the potential for enhanced electrokinetic dewatering of sludge on a wider scale. The technology shows promising results to consider the final sludge cake as a fuel for energy recovery from waste.