Utilization potential of poultry litter ash as phosphorus-based fertilizer

Abstract

A large quantity of poultry litter is globally generated as a result of expanding poultry industry. From several alternative technologies, one of the most feasible management for this waste is com-bustion, which exhausts poultry litter ash (PLA) as the main by-product. In this study, a PLA sample was examined for its utilization potential as a raw material for phosphorus-based fertilizer. According to the experimental results, Ca, P and K were determined as the major elements in the PLA sample with 29.54, 6.13 and 4.96%, respectively. Although the sample contains 2472 ppm Zn and 922 ppm Cu, their solubility determined by the leaching test is below the toxicity limit for haz-ardous waste. In terms of the major elements, about 290 mg/l Ca was detected in the leachate, re-sulting in a pH value higher than 13, whereas P concentration was found only 0.0092 mg/l. These two crucial results constitute the major difficulties for direct use of the PLA as a fertilizer. On the other hand, a usable P-rich product with low heavy metal contents and neutral pH can be obtained through acidification, heavy metal removal and neutralization processes. However, in this case, the feasibility of processes to be used should be carefully considered in economic point of view. In conclusion, direct application of the PLA sample examined as P-based fertilizer is not possible without any pre-treatments mainly due to its very high alkalinity and the low water solubility of P.