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| Limestone iron coating and its phosphorus removal improvement |
| Received:March 15, 2020 |
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| KeyWord:constructed wetland;total P;limestone;iron coating |
| Author Name | Affiliation | E-mail | | SHI Jia-cheng | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | CHEN Can-ming | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | GAO Ting | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | WEI Ze-bin | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | WU Qi-tang | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | wuqitang@scau.edu.cn |
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| Abstract: |
| In order to obtain a low-cost iron coating method suitable to constructed wetland substrate for rural domestic sewage treatment, this study compared limestone and river sand as substrates for Fe-coating in laboratory experiments, using three types of Fe-containing solutions:FeCl3, FeSO4 and Fe(OH)3 colloids. Four methods were employed for the addition of these Fe solutions:soaking the substrate in the solution without re-collecting, re-collecting after soaking for 2 h, re-collecting immediately after soaking for 1 min, and spraying Fe solutions onto the substrate. Three drying methods, drying at 105℃, drying under sun-right, and natural drying under roof, were compared. A small constructed wetland filled with Fe-coated limestone was set-up and operated to verify its effectiveness. The method of Fe coating as per the laboratory experiments is as follows:The limestone is immersed in a 1.5 mol·L-1 FeSO4 solution, re-collect the limestone after the full contact with the FeSO4 solution for 1 min, and the Fe-containing liquid film on the limestone dried naturally under roof. The batch adsorption test showed that the removal rate of total P from domestic sewage by limestones was improved from 22.7% to 80.6% for the Feloaded limestone. The removal rate of total P by constructed wetland with Fe-coated limestone was increased by 10% to 15% compared with the ordinary limestone wetland. |
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