Optimization of chicken manure combustion parameters in the aspect of phosphorus recovery

PurposeThe increasing demand for phosphorous for the production of mineral fertilizers forces the continuous development of research and new technologies in the field of obtaining it from sources other than phosphate rocks. This paper presents an analysis of optimizing the combustion parameters of chicken manure in the aspect of phosphorous recovery. Methods The combustion process was carried out in different time (3-8 hours) and temperatures (700-900oC) in laboratory of electric furnace. The content of macro and micronutrients was determined by XRF and ICP-OES analysis. To identify the mineral composition of ashes, the XRD analysis was applied. The content of total phosphorus in ash extracts was determined by photometric method. Results Concentration of p 2O5 in ash samples detected by ICP-OES and XRF was comparable, 30.37 wt.% and 31.77 wt.% at 900oC, 26.27 wt.% and 26.71wt.% at 700oC and 25.31wt.% and 25.00 wt.% at 500oC, respectively. The mineral composition of ashes showed two phases: crystalline and amorphous. The estimated values of p 2O5 content in crystalline phase was 14.83wt.% at 500oC, 20.96wt.% at 700oC and 23.80wt.% at 900oC. The estimated p 2O5 content in amorphous phase was 10.48wt.% at 500oC and decreased at higher temperature to 5.31wt.% at 700oC and 6.57wt.% at 900oC. Conclusion The chemical composition of ashes from chicken manure depends on the combustion temperature. The highest concentration of phosphorous in their bioavailable forms was determined for samples burned in 500oC. The results indicate that a valuable source of phosphorous is the amorphous phase.