Phosphate removal from wastewater by using low-cost adsorbent materials

Abstract

The need to develop new technologies for removing and recovering phosphates from wastewater has derived from increasing the demand for these sustainable compounds, setting stricter limits for discharges in order to prevent eutrophication of natural water resources, as well as tightening sludge disposal restrictions derived from wastewater plants. Removing phosphates from domestic and industrial wastewater and rationalizing the use of fertilizers in agriculture lead to reducing the main factors driving the proliferation of aquatic vegetation and hence, the secondary pollution of surface water. The subject of this work is part of an environmental issue and proposes a method for wastewater depollution by using adsorption processes, taking into account the technical and economic aspects, by using low-cost adsorbents namely pumice stone and autoclaved cellular concrete (BCA). The objectives of the present study were mainly to model phosphorus adsorption processes using Langmuir and Freundlich classical isotherms and to understand the influence of pH on these processes. For a complete description of the process, isotherms were determined at pH values of 3 and 9, and mathematical processing of experimental data was attempted based on the above mentioned models. Based on the experimental results obtained, it is observed that the removal of phosphate ions from the wastewater by adsorption processes on pumice stone and BCA is more efficient at a strongly acidic pH, and the Freundlich thermodynamic model offers better process behavior.