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In this research work, raw poultry manure biochar (RPM-B) was post-modified by two metal salts and then evaluated for P recovery from aqueous solutions in batch mode. The modified biochar characterization showed that RPM-B impregnation with aluminum and manganese salts led to a significant improvement of their surface properties through the pH-zero charge reduction as well as the specific surface areas and the functional group contents increase. Phosphorus recovery tests indicated that the post-treated biochar with AlCl3 (RPM-B-Al) and with KMnO4 (RPM-B-Mn) exhibited relatively high recovery efficiencies with Langmuir’s adsorption capacities of 23.5 and 8.4 mg g−1, respectively. Kinetics and isothermal data modeling, as well as the in-depth analytical characterization of the post-modified biochars before and after adsorption, indicates that P recovery occurs homogeneously on monolayer surfaces through mainly anion exchange, precipitation, and electrostatic interactions. On the other hand, P desorption efficiency increases with the desorbing solution pH values. The best P desorption yields were observed for an initial pH of 9.0 to 78% and 80% for RPM-B-Al-P and RPM-B-Mn-P, respectively. All these results suggest that RPM-B-Al and RPM-B-Mn could be considered promising materials for phosphorus recovery from wastewaters with a possible reuse in agriculture as potential soil amendments.

In this study, nutrients release/adsorption from/by raw poultry manure-derived biochar produced at a pyrolysis temperature of 600 &deg, C (RPM-B) was assessed under static and dynamic conditions. Batch sequential leaching experiments of RPM-B for a total contact time of 10 days showed that both phosphorus and potassium were slowly released but with higher amounts compared to various other animal- and lignocellulosic-derived biochars. The cumulated released P and K amounts were assessed to 93.6 and 17.1 mg g&minus, 1, which represent about 95% and 43% of their original contents in the RPM-B, respectively. The column combined leaching/adsorption experiments showed that amending an alkaline sandy agricultural soil with two doses of RPM-B (at 5% and 8% w:w) resulted in an efficient retention of NO3-N and NH4-N, and on the contrary, important leached amounts of PO4-P, K+, Mg2+, and Ca2+ but with relatively slow kinetic release rates for a long period. Even after 40 days of dynamic leaching, these latter nutrients continued to be released with kinetic rates lower than 10 mg kg&minus, 1 d&minus, 1. Thus, compared to synthetic fertilizers, RPM-B valorization as organic amendment for poor semiarid soils could be considered as an attractive, eco-friendly, and sustainable waste recycling option.