Title : Reducing excess phosphorus in agricultural runoff with low-cost, locally available materials to prevent toxic eutrophication in hoar areas of Bangladesh

Authors : Ayesha Sharmin, Md Abdul Hai, Md Mainul Hossain, Mohammad Moshiur Rahman, Md Baki Billah, Sohidul Islam, Mohammad Jakariya, Garon C. Smith

Abstract : Two potential sorbent materials were investigated for their ability to remove excess phosphate from agricultural runoff in Bangladesh. Because they are low in cost, locally available, and require few extra resources to prepare, they offer viable strategies to prevent hazardous algal blooms that can catastrophically take out fish and water bird populations. The first material is rice hulls that have been burned, calcined and enhanced with FeCl3. The second, and more appealing, is iron-rich Sylhet sands that are simply washed. Sorption trials were run in both batch and column modes. Optimal conditions for phosphate removal were pH 5 and a 3-h contact time. Fe-treated rice hull ash removed 78.5% of the phosphate from a 5-ppm test solution. The Sylhet sand achieved a 49.6% reduction. When an actual sample of runoff from the Tangua hoar was subjected to the sorbents, the rice hull ash removed 83.8% and the Sylhet sand removed 83%. Both materials showed signs of being re-useable. With the rice hull ash, 42.9% of the phosphate could desorbed while with the Sylhet sand, 71.6% of the phosphate was desorbed. Once desorbed, 74% of the phosphate could be recovered for fertilizer feed stock by precipitating it out as ferric phosphate, FePO4.

Journal : Groundwater for Sustainable Development Volume : 10 Year : April 2020 Issue : 100348
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