Novel Recovered Compound Phosphate Fertilizer Produced from Sewage Sludge and Its Incinerated Ash

Abstract

Current disposal methods of sewage sludge (SS) and its incinerated ash (ISSA) do not allow for the recycling of the phosphorus (P) present. The aim of this study was to fabricate a P compound fertilizer by using an optimal SS-derived biochar (SSB) with enhanced inherent Ca–P content to load P from the P extract of ISSA. For this purpose, SS was impregnated with four agents (MgCl2, CaCl2, MgO, and CaO) at mass ratios of 20 or 10% and pyrolyzed at 700 or 300 °C. Characterization of the produced SSBs indicated that those with 20% MgCl2, CaO, and MgO added and pyrolyzed at 700 °C exhibited high surface areas, abundant mesopores, and abundant plant-valuable P. When in contact with the P extract, these three SSBs showed the highest P adsorption efficiencies among the obtained SSBs but CaO/MgO-impregnated SSBs have more metal coprecipitation. The postsorption SSBs were P-enhanced and alkalinity decreased, which are favorable for fertilizer application. Furthermore, a pot experiment verified that these three postsorption SSBs had a comparable P fertilizer effect to that of the commercial P fertilizer. Therefore, the MgCl2-impregnated SSB with P loading from the ISSA extract has potential as a P fertilizer alternative that can support global P sustainability by reclaiming P from SS and ISSA.

Tailoring the phosphorus release from biochar-based fertilizers: role of magnesium or calcium addition during co-pyrolysis

“…The pH of the solution was lower as well and stabilized around 7.4. The higher phosphate release from MgPA-BC compared to CaPA-BC was in agreement with Fang et al 20 Six models were used to assess the phosphate release from the modied biochars (Table S1 in ESI †). Based on the R 2 and SE values, the phosphate release from both MgPA-BC and CaPA-BC was best described by the power function (Table 3).…”

“…Adsorbed P was suggested to be rapidly released, whereas the inherent P in the biochars was released more slowly. 20 Also the co-pyrolysis of sawdust and switchgrass with triple superphosphate or bone meal at 500 °C produced P-loaded biochars with slow P release kinetics in water. 21 In these previous studies, the gradual P release from biocharbased fertilizers has been linked to the presence of poorly soluble Mg and/or Ca phosphate phases.…”

Chemical Soil-Biological Engineering Theoretical Foundations, Technical Means, and Technology for Safe Intrasoil Waste Recycling and Long-Term Higher Soil Productivity

“…New soil contamination mitigation strategies are becoming real . Our intrasystem of the gasification byproduct recycling is more promising compared to environmentally dangerous phosphate recovering from sewage sludge incineration ash …”

“…The dispersed waste utilization intrasoil is promising in different cases of pollution. It will prevent biotoxicity of biochars. , The priority conditions for soil amelioration and remediation, high quality environment, high-rate biogeochemical processes and yield, and economic benefit gaining will be provided in different applications. ,,, The reversible biological carbon sequestration will become real because of higher soil biological productivity and increased soil-biological carbon turnover. , …”

“…63 Our intrasystem of the gasification byproduct recycling is more promising compared to environmentally dangerous phosphate recovering from sewage sludge incineration ash. 64 A facile approach-based remediation technology is dangerous for the complicated soil ecosystem. 65 Soil organic matter is a multifaceted intricate phenomenon.…”