Ramírez W A, Domene X, Ortiz O, Alcañiz J M
CREAF (Center for Ecological Research and Forestry Applications), and Unit of Ecology, Department of Animal and Plant Biology and Ecology, Autonomous University of Barcelona, E-08193 Bellaterra, Barcelona, Spain.
Bioresour Technol. 2008 Oct;99(15):7168-75. doi: 10.1016/j.biortech.2007.12.072. Epub 2008 Feb 14.
In order to evaluate potential toxic effects of stabilized sewage sludge that are currently applied to agricultural soils, three types of municipal sewage sludge and one pig slurry were subjected to phytotoxicity assays using three plants (Brassica rapa, Lolium perenne and Trifolium pratense). Equivalent batches of aerobically and anaerobically-digested sludge (F) from two municipal wastewater treatment plants, were composted (C) or thermally dried (T). In addition, one anaerobically-digested and thermally-dried pig slurry (P) was tested. A seedling growth test was performed in accordance with the OECD Guideline 208A, using seed emergence and shoot length as endpoints to identify the inhibition of plants growing in increasing doses of sludge. A correlation analysis between EC50 and physico-chemical parameters or the pollutant burden of the biosolids was also calculated. In all tests, lower germination rates were observed for T. pratense than for L. perenne and B. rapa. A moderate stimulatory effect on shoot length at low doses was observed for the three plants. In these wastes, a strong positive correlation was found between higher values of EC50 (less toxicity) and the stability degree of their organic matter, and a negative correlation between EC50 and total N, hydrolysable N or NH4-N content. No correlations were found with heavy metal or organic pollutant content in those wastes. Results indicate that digested sludge, thermally-dried sludge and thermally-dried pig slurry have non-negligible short term phytotoxic effects, and confirm that composting is an effective sludge treatment for the reduction of phytotoxicity.
为了评估目前施用于农业土壤的稳定化污水污泥的潜在毒性效应，使用三种植物（油菜、黑麦草和红三叶草）对三种类型的城市污水污泥和一种猪粪进行了植物毒性试验。来自两个城市污水处理厂的等量好氧和厌氧消化污泥（F）批次，进行了堆肥处理（C）或热干燥处理（T）。此外，还测试了一种厌氧消化和热干燥的猪粪（P）。根据经合组织准则208A进行了幼苗生长试验，以种子萌发和芽长作为终点指标，来确定在污泥剂量增加时对植物生长的抑制作用。还计算了半数有效浓度（EC50）与物理化学参数或生物固体污染物负荷之间的相关性分析。在所有试验中，观察到红三叶草的发芽率低于黑麦草和油菜。在低剂量下，观察到这三种植物的芽长有适度的刺激作用。在这些废弃物中，发现较高的EC50值（毒性较小）与其有机质稳定程度之间存在强正相关，而EC50与总氮、可水解氮或铵态氮含量之间存在负相关。在这些废弃物中未发现与重金属或有机污染物含量的相关性。结果表明，消化污泥、热干燥污泥和热干燥猪粪具有不可忽视的短期植物毒性效应，并证实堆肥是一种有效的污泥处理方法，可降低植物毒性。
