A new method for lake restoration, impacting on circular economy (CE)

Abstract

The key aim of the chapter is to incorporate innovative technology that can be used to treat eutrophic waters. A new environmentally friendly method is focused on the "teabag" process, under which P-inactivation agents were stored in water-permeable bags and submerged in the water column to trap P, which is one of the primary causes of eutrophication. In specific, composite lanthanum-modified bentonite (LMB) and Fe-modified bentonite (FMB) were investigated, and bench-scale batch tests were performed to examine their adsorption efficacy as slurry and as tea-bag. Moreover, the adsorption isotherms and kinetics were also studied. Experimental outcomes revealed that LMB and FMB (as teabag) achieved a maximal sorption capacity of 7.80 and 25.1 mg/g, accordingly, being considered as acceptable P rates for natural eutrophic waters. The "teabag" approach avoids the material covering the bottom sediment, thereby eliminating the occurrence of smothering of benthos. Also, P-adsorbents are also suitable for other agricultural uses like that of soil improver. Conclusively, it was signified the of utmost importance perspective of LMB and FMB composite clays' recycling at later agricultural uses, since it sustains beneficial ecological impacts: routes of the circular economy (CE).