Adsorption of phosphorus from eutrophic seawater using microbial modified attapulgite - cleaner production, remove behavior, mechanism and cost-benefit analysis

Abstract

A novel seawater phosphorus adsorption material (AT@SiB-X) has been developed through the modification of attapulgite (AT) by silicate bacteria (SiB-X) in this study, enabling efficient separation of phosphate from seawater. The phosphorus adsorption capacity of AT@SiB-X reached 9.54 mg/g, and its specific surface area and pore volume increased by 49.3–175.0 % and 12.5–47.4 %, respectively when compared with unmodified AT. Moreover, the SiB-X accelerated the decomposition of minerals and dissolution of metal elements (e.g., Ca, Mg, Al and Fe), resulting in a 16.7-fold increase in phosphorus adsorption. The adsorption process is controlled by multiple mechanisms, including electrostatic attraction, ion exchange, complexation, chemical precipitation, and physical adsorption. The path analysis suggested that both physical structure and chemical element release played a joint role in phosphorus adsorption. What’s more, pore structure change of the material was the main mechanism affecting its adsorption capacity. The fixed bed column dynamically removed 98 % of phosphorus from mariculture wastewater, which achieved of 7.02 ¥/ton wastewater treatment cost. The production cost of AT@SiB-X is about 2000 ¥/ton, which is much lower than the current average market value of commercial adsorption materials (e.g., activated carbon). The experimental results demonstrated that the AT@SiB-X exhibited excellently in regeneration, which is resulted by the impressive adsorption efficiency and little possibilities of overcrowding. Thus, it is highly feasible to achieve commercial application of microbially modified attapulgite.