Department of Soil and Environment, Swedish University of Agricultural Sciences, Box 7014, SE 750 07 Uppsala, Sweden.
Environ Technol. 2009 Oct;30(11):1215-26. doi: 10.1080/09593330903213879.
Large amounts of phosphorus are present in organic waste, mainly in sewage sludge and animal by-products. Increasingly, the waste is incinerated and phosphorus ends up in the ash. Sustainable waste management requires the beneficial reuse of phosphorus present in such ash. The first necessary step when recovering phosphorus from ash is dissolution by acid. The objective of this study was to quantify the acid requirement for phosphorus dissolution from sewage sludge ash and animal carcass ash. Both the amount of acid applied and its concentration were varied. Furthermore, phosphorus dissolution was optimized by controlling the pH during acid addition. Elemental analysis of sewage sludge ash showed that it comprised 6-10% P, 7-18% Ca, 2-11% Fe and 3-9% Al. The elemental content of animal carcass ash was even higher: 18% P and 30% Ca. The amount of acid required to obtain >85% phosphorus dissolution from sludge ash was 0.39-0.78 kg H2SO4 kg(-1) ash, depending on the total cation/phosphorus equivalent ratio. The amount required to obtain the highest possible P dissolution within two hours (73%) from animal carcass ash was 0.69 kg H2SO4 kg(-1) ash. Lower amounts of sulphuric acid were required for P dissolution in ashes of sludge from a bio-P treatment process and animal carcass, compared with the theoretical acid requirement for apatite dissolution. Applying pH control during dissolution resulted in reduced acid consumption (20%) and enabled more than 85% phosphorus dissolution from sludge ash at pH 2.0 in the two-hour dissolution time.
大量的磷存在于有机废物中，主要存在于污水污泥和动物副产品中。越来越多的废物被焚烧，磷最终进入灰烬中。可持续的废物管理需要对这种灰烬中的磷进行有益的再利用。从灰烬中回收磷的第一步是通过酸溶解。本研究的目的是量化从污水污泥灰和动物尸体灰中溶解磷所需的酸量。改变了施加的酸量及其浓度。此外，通过控制加酸过程中的 pH 值来优化磷的溶解。污水污泥灰的元素分析表明，其含有 6-10%的磷、7-18%的钙、2-11%的铁和 3-9%的铝。动物尸体灰的元素含量更高：18%的磷和 30%的钙。从污泥灰中获得超过 85%磷溶解所需的酸量为 0.39-0.78 kg H2SO4 kg(-1) 灰，具体取决于总阳离子/磷当量比。在两小时内（73%）从动物尸体灰中获得最高可能磷溶解所需的酸量为 0.69 kg H2SO4 kg(-1) 灰。与磷灰石溶解的理论酸需求相比，生物磷处理过程和动物尸体产生的污泥灰中磷溶解所需的硫酸量更少。在溶解过程中应用 pH 值控制可减少酸的消耗（20%），并可在两小时的溶解时间内将 pH 值为 2.0 的污泥灰中的磷溶解率提高到 85%以上。
