Institute of Plant Nutrition, Justus-Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany.
Division 4.4 Thermochemical Residues Treatment and Resource Recovery, Bundesanstalt für Materialforschung und-prüfung (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
Waste Manag. 2017 Apr;62:194-203. doi: 10.1016/j.wasman.2017.02.019. Epub 2017 Feb 24.
Sewage sludge has one of the highest phosphorus (P) recovery potentials of all waste materials. Therefore, P-recycling from sewage sludge could contribute to closing the P-cycle. Recently, various thermal processes for P-recovery have been developed, but there is still a demand for information on the effect of different process parameters (e.g. additives and temperature) on P-speciation and especially on the fertilization performance. In the present study, two common methods (low-temperature conversion at 400-500°C and thermochemical treatment at 950°C) were investigated and combined to produce highly bioavailable P-fertilizers from two different types of sewage sludge based on chemical phosphorus precipitation (Chem-P) and enhanced biological phosphorus removal (Bio-P). The results of P-fractionation, X-ray diffraction analysis, and pot experiments with maize showed that Bio-P sludges attain high P-plant-availability after treatment at low temperatures (400°C). In contrast, Chem-P sludges can adequately be treated at higher temperatures under reductive conditions with sodium additives to form highly bioavailable calcium-sodium-phosphate. Additionally, also highly heavy-metal contaminated sludges can be thermochemically treated at high temperatures to achieve the legal requirements for fertilizers.
污水污泥的磷（P）回收潜力是所有废物中最高的之一。因此，从污水污泥中回收磷有助于闭合磷循环。最近，已经开发出各种用于磷回收的热工艺，但仍需要有关不同工艺参数（例如添加剂和温度）对磷形态和特别是施肥性能影响的信息。在本研究中，研究了两种常见的方法（400-500°C 的低温转化和 950°C 的热化学处理），并将其结合起来，基于化学磷沉淀（Chem-P）和增强的生物除磷（Bio-P），从两种不同类型的污水污泥中生产高生物可利用的磷肥料。磷形态分析、X 射线衍射分析和玉米盆栽试验的结果表明，Bio-P 污泥在低温（400°C）处理后即可获得高磷植物有效性。相比之下，Chem-P 污泥可以在添加还原剂和钠盐的高温条件下进行适当处理，形成高生物可利用的钙-钠-磷酸盐。此外，即使是重金属污染严重的污泥也可以在高温下进行热化学处理，以达到肥料的法定要求。
