Phosphorus-Rich Ash from Poultry Manure Combustion in a Fluidized Bed Reactor

Abstract

The aim of this study was to examine the physico-chemical and phase characteristics of ash obtained in the process of the combustion of Polish poultry manure in a laboratory reactor with a bubbling fluidized bed. Three experiments, differing in the grain size and morphology of the raw material, the method of its dosing and the type of fluidized bed, were carried out. The contents of the main chemical components and trace elements in the obtained ash samples were determined using WDXRF, and the phase composition was examined through the XRD method. The morphology and the chemical composition of grains in a given micro-area using the SEM/EDS method were also investigated. The highest concentration of phosphorus (from 28.07% wt. to 29.71% wt. as P2O5 equivalent), the highest proportion of amorphous substance (from 56.7% wt. to 59.0% wt.) and the lowest content of unburned organic substance (LOI from 6.42% to 9.16%) (i.e., the best process efficiency), was obtained for the experiment in which the starting bed was quartz sand and poultry manure was fed to the reactor in the form of pellets. It has been calculated that in this case, the amorphous phase contains more than half of the phosphorus. The method of carrying out the combustion process has a significant impact on the phase composition and, consequently, on the availability of phosphorus.

Early layer formation on K-feldspar during fluidized bed combustion with phosphorus-rich fuel

“…EDS analysis revealed the presence of K and S in these areas, which could indicate K 2 SO 4 formation. The presence of K 2 SO 4 has been observed in previous studies with chicken manure [9,18,[36][37][38] and in sewage sludge [39]. Similar structures can be observed also for the samples extracted after 8 h. Thus, it can be assumed that K 2 SO 4 forms during thermal conversion of chicken manure and accumulates preferentially within cavities and over time, migrates through the cavities deeper into the particles.…”

“…The speciation of phosphorus plays a major role regarding plant availability [41][42][43]. The formation of an amorphous phosphoruscontaining phase could be interesting for the application of the used bed material as a fertilizer, because amorphous phosphorus showed a higher plant availability than crystalline phosphorus [10,37,44]. Alternatively, the formation of alkali-phosphates was found to increase the fertilization value of phosphorus-rich sewage sludge ash [45][46].…”

Review of Phosphorus Chemistry in the Thermal Conversion of Biomass: Progress and Perspectives

“…130 Phosphorus was also later reported to be largely associated in amorphous form in ashes from combustion of chicken manure. 618 Another study also reported that, in gasification of poultry litter, phosphorus was found as stable phosphates in the cyclone ash and only traces of gaseous phosphorus species were detected using MBMS. 126 5.2.3.…”

“…Normally, XRD analysis is only performed on the final biomass residues, and does therefore not provide a lot of information on the transformation pathways, but it gives an indication of the fate of phosphorus in thermal conversion of biomass. In an attempt to investigate what crystalline phosphates are most commonly found in biomass residues, the reported phases detected in 384 samples, from 65 references (refs , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , – , , , – , , , , – ) were compiled in this work. The result of the compilation is shown in Figure .…”

“…Crystalline phosphorus phases reported to be present in residues from different types of biomass, including biomass blends (left) (refs , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , – , , , – , , , , – ) grain- and seed-based biomass (upper middle) (refs , , , , , , , , ) animal biomass (upper right) (refs , , , , , – ) sewage sludge (lower middle), (refs , , , , , , , , , , , , , , , , …”