Removal of phosphate from fresh water using bioirontech process

• Main Author: U Yasmeen
• Other Authors: Volodymyr Ivanov
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/15847
• Institution: Nanyang Technological University

BioIronTech is a biological process of employing iron-reducing bacteria to reduce ferric iron (Fe3+) to ferrous iron (Fe2+) under strict anaerobic conditions. The reduced iron can then react with the phosphate (PO43-) to form insoluble ferrous phosphates. This chemical reaction can be applied to remove phosphates from freshwater. This research report focuses on the removal of phosphate from fresh water using the BioIronTech process as phosphate plays the role of limiting nutrient for the occurrence of eutrophication. A series of experiments were conducted with samples of freshwater from the same source, which was passed through biofilters containing iron ore. Levels of phosphate and ferrous iron were periodically monitored to study the effectiveness of BioIronTech to remove phosphate from freshwater. Other tests carried out include ORP, pH, turbidity, TOC, colour, chlorophyll-a and total iron. This report also discusses briefly the procedures used and the apparatus required in this process. From the results obtained, there is sufficient evidence that ferric iron is reduced to ferrous iron in the anaerobic columns. The reduction of phosphate varied proportionally to the amount of ferrous iron present proving the reaction between ferrous iron and phosphate. At the end of the second trial, the water passing through the iron ore biofilter showed a phosphate concentration of zero. This denotes a 100 percentage phosphate removal; however the control system also showed a 90% phosphate removal. Thus, the entire removal of phosphate could not be attributed to the BioIronTech process. Instead the interference of other forms of phosphorus removal such as Enhanced Biological Phosphorus Removal which employs phosphate-accumulating organisms has to be acknowledged also. Nonetheless, the formation of high amounts of reddish-brown sediments in the iron ore tank, positively points to precipitation of ferric iron compounds in the system. This indicates the occurrence of BioIronTech process in the iron ore system. In addition, eutrophication did not occur in the system with iron ore biofilter, while the control system showed obvious signs of eutrophication. Thus the experiment conducted proved the ability of BioIronTech to prevent eutrophication.