Master of Science in Civil Engineering (MSCE)
Civil and Environmental Engineering
High iron concentrations in the water used for aquaculture results in stock losses. It is necessary to drop down the iron concentrations to levels which can be handled by the fish. Electrocoagulation followed by floating bead bed filtration was used to remove iron from water. Electrocoagulation was carried out using aluminum electrodes. The flocs formed in the coagulation tank were then filtered out using 2-3 mm polyethylene floating beads having specific gravity of 0.92 gm/cm3. Proper retention time of ≥ 10 min, pH of 6±0.2, Al3+ coagulant dosage of about 9 mg-Al3+/ L and flow rate ≤ 0.4 gpm resulted in dropping down the iron concentrations to 0.3 mg- Fe/ L within 10 minutes of run time. Adsorption- oxidation mechanism is applied for forming iron coated media. Iron precoated media can accelerate iron removal by improving adsorption due to increase in surface area of media. The adsorption- oxidation mechanism was used to form iron coatings on the polyethylene bead media. Iron accumulation ranging from 5.93 * 10-5 mg/ cm2 to 7.71* 10-5 mg/ cm2 was observed at the end of three days. The iron precoated beads were later checked for their iron removal efficiency by prior application of electrocoagulation. The iron removal efficiencies of fresh beads vs iron precoated beads were then compared. Iron precoated beads proved better than fresh beads with 3.5 times increase in its iron removal efficiency. Polyethylene beads used, lacked a negative surface compared to sand media and required a longer time for coat formation. Iron removal by application of adsorption- oxidation method may be used at places where time of treatment is not the constraint.
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Phadke, Asmita Anil, "Iron Removal Using Electro- coagulation Followed By Floating Bead Bed Filtration" (2014). LSU Master's Theses. 1256.