Unrefined aluminosilicates-based coagulants & sorbents for effective removal of phosphorus from wastewater – employment of natural halloysite nanostructures in intensification of a multi-mechanism process

The results of laboratory tests and preliminary industrial research related to the original use of coagulants produced from aluminosilicate clay - activated halloysite, based on exemplary unrefined geological mineral, with natural nanostructural elements – nanotubes, nanoplatelets, nanospheres for multi-mechanistic integrated sorption and coagulation-based capture of phosphorus from multi-component sewage are presented. According to the Circular Economy (CE) approach, the use of simple methods of physical pretreatment of halloysite, without chemical functionalization or purification, was a conscious research strategy, justified by technological, economic and environmental aspects. Product manufactured on the basis of unrefined naturally-nanostructural aluminosilicates - halloysite mineral, after dedicated functionalization, can simultaneously act as a sorbent, coagulant and as a weight for the emerging aggregates - flocs, accelerating their sedimentation. The presented original technological concept of a simplified, thus cleaner production process of an adsorbent & coagulant based on halloysite has been positively verified for real sewages. The research based on the selected, exemplary geological deposit of Dunino in Poland, where the mineral containing mainly naturally-nanostructural halloysite but also kaolinite, hematite, magnetite, quartz, magnesioferrite, rutile, ilmenite, geikielite, goyazite, crandallite shown that leaving the minerals naturally co-present in the raw material has a positive effect on the more effective separation of phosphorus from sewage. Their co-presence, as well as elements substitutions both in the spatial nanostructural forms of halloysite and on its surface has proven to be technologically beneficial due to the synergistic physical and chemical interactions, providing in effect more effective sorption and coagulation processes. The aim of this study was to evaluate the effectiveness of phosphates removal from the real municipal wastewater using natural, chemically untreated halloysite and to identify the process dependencies between its fractional composition and the resulting coagulation and sorption efficiency in separation of phosphorus compounds from solutions of variable composition.