Electrocoagulation for water and industrial wastewater

• Main Author: Lu, Samuel Weihan
• Other Authors: Lim Teik Thye
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Environmental engineering::Water treatment
• Online Access: http://hdl.handle.net/10356/60058
• Institution: Nanyang Technological University

Clean water has always been a precious commodity and this is especially so in Singapore where there are no natural freshwater resources. In order to minimize the use of potable water in industrial uses such as wafer fabrication, boiler water or antifreeze, recovered water is used instead. Electro-coagulation has been a highly sought after alternative to chemical coagulation due to its benefits of not having to dispose any sludge and cheaper costs. This research looks at the capabilities of electro-coagulation to recover different types of used household water by removing its turbidity, total suspended solids and oil content. The household water types tested are laundry water derived from a washing machine discharge, Nanyang Lake water and dishwashing water. The goal is to test various parameters that affect electro-coagulation namely; electrode spacing, current density and type of electrode (aluminium or iron) used within a set duration. This has led to findings that indicate aluminium is the better coagulant and in this case, not necessarily the closest electrode spacing and the highest current density is the most optimal. From the experimental results, a spacing of 3 cm appears to have a better efficiency than a spacing of 1 cm due to the latter interfering with the production of H2 bubbles. The highest current density of 8 mA/cm2 has a small increase in turbidity removal efficiency as compared to 7 mA/cm2, thus rendering it inefficient as compared to the removal efficiency increment between the other current densities. Increasing the current density passing through the electrodes is a direct way to increase the efficiency of electro-coagulation while an indirect method may be adjusting the inter-electrode distance to facilitate higher voltage movement across the electrodes. Based on these findings, it can be concluded electro-coagulation is indeed cheaper and as efficient as, if not an even better alternative than chemical coagulation.