Development of a natural coagulant from Albizia lebbeck seeds for application in turbidity removal from water intended for human consumption

• Albizia Lebbeck seed can be used as a natural coagulant to remove turbidity • The extraction of the natural coagulant depends on the concentration of NaCl • Particle size of the seed powder has a negligible effect on the removal efficiency • Oil extraction from Albizia seeds does not improve turbidity removal • The natural coagulant keeps neutral the water pH unlike aluminum sulfate Surface water is essential as a water resource in small communities, most of which do not have access to potable water; not all resources are safe for human consumption, so treating them with processes that often involve coagulants such as aluminium sulphate is essential and effective. However, aluminium sulphate is often a bioaccumulative compound and represents a risk to human health. For this reason, this research focused on the study of Albizia lebbeck (AL), in order to evaluate its coagulant capacity to remove turbidity in raw water, and to provide more sustainable, safe, and effective treatment alternatives. For the analysis of AL, seed lots were collected in the city of Cartagena, Bolívar, Colombia. The turbidity removal efficiency of coagulant prepared with and without oil extraction was determined using the jar test, varying the dose, the percentage of NaCl, the amount of seed powder, and the particle size of the seeds. The results showed that, for AL, the optimum dose is 8.5 mL/L, prepared with 10 g of 0.5 mm seeds at 4% NaCl, obtaining an efficiency of 93.65% and 93.31% with and without oil extraction, respectively. Finally, the removal efficiency and sedimentation time of the prepared natural coagulant were compared with those of aluminium sulphate, where it was found that the latter is more efficient (99.05%) at a lower concentration (2.4 mL/L) and achieved sedimentation in less time (8–9 minutes). However, the coagulant prepared from AL emerges as an environmentally friendly alternative for water clarification processes.