Department of Agricultural Sciences, Alma Mater Studiorum, University of Bologna, Viale G. Fanin, 44, 40127 Bologna, Italy.
Department of Chemistry "Giacomo Ciamician", Alma Mater Studiorum, University of Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
Waste Manag. 2017 Nov;69:353-359. doi: 10.1016/j.wasman.2017.08.029. Epub 2017 Aug 31.
Composting is considered a suitable process for organic waste management, providing stable products that can be safely utilized as fertilizers, but little is still known about the variation of phosphorous (P) extractability during the stabilization process. In this work, sequential chemical extraction (SCE) with increasing strength extractants (HO; 0.5M NaHCO pH 8.5; 0.1M NaOH, 1M HCl) was applied for P speciation over 56days of composting of either agro-industrial or urban wastewater sludge with green waste treated (AIC; SSC) or not (AIC; SSC) with FeSO (2%v/v). Composting strongly reduced the HO-P, promoting the organic-P (P) mineralization from the labile fraction (HO+NaHCO 40%), in addition to the increases of NaHCO- and HCl-extractable inorganic-P (P) in both AIC and SSC (+20% on average). The FeSO treatment did not negatively affect the process, reducing the P mineralization during composting by increasing the NaOH-P, also protecting this fraction from fixation in the sparingly soluble fraction. The final P fractionation (%) was in AIC: NaOH (41)=NaHCO (38)>HCl (18)>HO (3); in AIC: NaOH (53)>NaHCO (24)=HCl (22)>HO (2); in SSC: NaOH (46)>NaHCO (29)>HCl (21)>HO (4) and in SSC: NaOH (66)>NaHCO (13)>HCl (20)>HO (1). Composting reduced the more easily leachable fraction (labile-P), reducing the risk of P loss by increasing the long-term available P fraction (NaOH-P). This was enhanced by the FeSO addition. Further investigation into soil behaviour and plant availability of P from this source is needed.
堆肥被认为是一种适合有机废物管理的方法，可提供稳定的产品，可安全用作肥料，但对于磷（P）在稳定化过程中的可提取性变化，人们知之甚少。在这项工作中，采用顺序化学提取（SCE）方法，使用强度递增的提取剂（HO；0.5M NaHCO₃ pH 8.5；0.1M NaOH，1M HCl），对农业-工业或城市污水污泥与经过（AIC；SSC）或未经（AIC；SSC）处理的绿肥进行了 56 天的堆肥后磷形态进行了分析。堆肥强烈降低了 HO-P，促进了从易分解部分（HO+NaHCO₃ 40%）中有机磷（P）的矿化，同时还增加了 AIC 和 SSC 中 NaHCO₃-和 HCl-可提取无机磷（P）（平均增加 20%）。FeSO₄处理并没有对该过程产生负面影响，而是通过增加 NaOH-P 来减少堆肥过程中的磷矿化，同时还保护了这部分磷免受难溶性部分的固定。最终的磷分级（%）为在 AIC 中：NaOH（41）=NaHCO₃（38）>HCl（18）>HO（3）；在 AIC 中：NaOH（53）>NaHCO₃（24）=HCl（22）>HO（2）；在 SSC 中：NaOH（46）>NaHCO₃（29）>HCl（21）>HO（4）和在 SSC 中：NaOH（66）>NaHCO₃（13）>HCl（20）>HO（1）。堆肥降低了更容易浸出的部分（易分解磷），通过增加长期可用的磷部分（NaOH-P），降低了磷损失的风险。这一点通过添加 FeSO₄得到了增强。需要进一步研究该来源的磷在土壤中的行为和植物有效性。
