Investigation of characteristics and application of food waste-derived bone char on plant growth

Abstract

Waste bone, a by-product originating from animal husbandry and food industry, primarily ends up in landfills and may cause soil pollution if no treatment method is applied. In this article, pork bone char (PBc), a porous carbonaceous material, was manufactured by pyrolyzing waste pork bones collected from food waste sources. The investigation covered temperatures from 400 to 800 °C in limited oxygen conditions. The prepared PBc samples were characterized and applied as an alternative source of phosphorus fertilizer by evaluating the growth of Ipomoea aquatica planted on the PBc/soil mixture and assessing the properties of SPBc.As a result, the PBc materials exhibit a clear hydroxyapatite mineral structure along with an abundance of micro-mesoporous features. The SPBc samples demonstrate a significant change in phosphorus concentration (up to 1.6 %) compared to PBc non-amended soil, and the growth of the Ipomoea aquatica plant differed significantly from the plant not fertilized by PBc. The results after four weeks indicate that samples added with PBc synthesized at temperatures of 500, 600, and 700 °C promoted its vigorous growth corresponding to the ratio of Ca/P of hydroxyapatite. The specific surface area, pore volume, and average pore size by various pyrolysis temperatures can impact the release of phosphorus from the PBc into the soil, significantly influencing the growth of Ipomoea aquatica. The achieved outcome not only presents a promising substance for reducing reliance on conventional phosphorus fertilizers derived from apatite minerals but also establishes a means to pursue the objectives of sustainable development and a circular economy.