Abstract In current study, the effect of various organic substances as bulking agents (BAs) including wheat straw, pistachio hull wastes, and tree leaves at different levels (10, 25, 45% v/v) were investigated on total concentration and chemical forms of Cu, Pb, Cr, and As in sewage sludge (SS) compost prepared by windrow method. According to the results, the composting process (with/without BAs), due to losses of SS mass and volume, increased the total concentration of heavy metals (HMs) compared to the un-composted SS sample (RSS). Evaluation of HMs chemical forms in prepared compost sample without BAs application (CSS) showed that the composting process reduced the mobility factor of As (from 28% to 20%), Pb (from 11.6% to 9.3%), and Cr (from 14.5% to 9.2%) compared to the RSS. Application of three BAs considerably decreased the mobility factor of As (17.5-18.8%), Pb (4.8-7.9%), and Cr (1.4-6.8%) compared to CSS and RSS. Changes of Cu mobility in prepared compost samples showed an unclear trend, however in some treatments, due to transferred organic fraction into exchangeable and carbonate fractions, increasing of this factor was obvious. Generally, the composting appeared to reduce As, Pb, and Cr availability by stabilizing the three metals and making them more stable and less mobile. In addition, the BAs application effect on HMs behavior of SS compost samples were so different and no specific kind of BAs can be recommended as a superior BAs in SS composting process.

中文翻译：

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评估各种填充剂对污水污泥堆肥中砷、铜、铅和铬的含量和化学形态的影响

摘要 在目前的研究中，研究了不同水平（10%、25%、45% v/v）的小麦秸秆、开心果壳废料和树叶等各种有机物质作为填充剂（BAs）对总浓度和化学形态的影响。堆肥法制备的污水污泥 (SS) 堆肥中 Cu、Pb、Cr 和 As 的含量。根据结果​​，与未堆肥的 SS 样品 (RSS) 相比，堆肥过程（有/没有 BAs）由于 SS 质量和体积的损失，增加了重金属 (HMs) 的总浓度。在未使用 BAs (CSS) 的情况下对制备的堆肥样品中 HMs 化学形式的评估表明，堆肥过程降低了 As（从 28% 到 20%）、Pb（从 11.6% 到 9.3%）和 Cr（从 14.5 % 到 9.2%）与 RSS 相比。与 CSS 和 RSS 相比，三种 BA 的应用显着降低了 As (17.5-18.8%)、Pb (4.8-7.9%) 和 Cr (1.4-6.8%) 的迁移率因子。制备的堆肥样品中Cu迁移率的变化趋势不明显，但在某些处理中，由于有机部分转移到可交换部分和碳酸盐部分，该因素的增加很明显。一般来说，堆肥似乎通过稳定这三种金属并使它们更稳定和更小的流动性来降低 As、Pb 和 Cr 的可用性。此外，BAs 应用对 SS 堆肥样品的 HMs 行为的影响如此不同，没有特定种类的 BAs 可以推荐为 SS 堆肥过程中的优良 BAs。但在一些处理中，由于有机馏分转化为可交换馏分和碳酸盐馏分，该因素的增加是明显的。一般来说，堆肥似乎通过稳定这三种金属并使它们更稳定和更小的流动性来降低 As、Pb 和 Cr 的可用性。此外，BAs 应用对 SS 堆肥样品的 HMs 行为的影响如此不同，没有特定种类的 BAs 可以推荐为 SS 堆肥过程中的优良 BAs。但在一些处理中，由于有机馏分转化为可交换馏分和碳酸盐馏分，该因素的增加是明显的。一般来说，堆肥似乎通过稳定这三种金属并使它们更稳定和更小的流动性来降低 As、Pb 和 Cr 的可用性。此外，BAs 应用对 SS 堆肥样品的 HMs 行为的影响如此不同，没有特定种类的 BAs 可以推荐为 SS 堆肥过程中的优良 BAs。