Faculty of Engineering, University of Technology Sydney (UTS), P.O. Box 123, Broadway, NSW, 2127, Australia.
Faculty of Sciences & Technology (RealTek), Norwegian University of Life Sciences, P.O. Box 5003, NO-1432, Ås, Norway.
Environ Sci Pollut Res Int. 2024 Mar;31(12):18412-18421. doi: 10.1007/s11356-024-32497-6. Epub 2024 Feb 17.
The use of aluminium (Al) salts, particularly alum, in coagulation is a widespread and conventional treatment method for eliminating pollutants, including phosphorus (P) which can cause eutrophication, from wastewater. However, a significant challenge of this process is the substantial amount of sludge generated, necessitating proper disposal. Historically, land disposal has been a common practice, but it poses potential issues for plant life on these lands. Despite the associated drawbacks, sludge contains elevated concentrations of vital plant nutrients like P and nitrogen, presenting an opportunity for beneficial use in agriculture. Given the imminent scarcity of P fertilizers due to the eventual depletion of high-grade P ores, this review explores the potential advantages and challenges of utilizing Al sludge as a P source for plants and proposes measures for its beneficial application. One primary concern with land application of Al sludge is its high levels of soluble Al, known to be toxic to plants, particularly in acidic soils. Another issue arises from the elevated Al concentration is P fixation and subsequently reducing P uptake by plants. To address these issues, soil treatment options such as lime, gypsum, and organic matter can be employed. Additionally, modifying the coagulation process by substituting part of the Al salts with cationic organic polymers proves effective in reducing the Al content of the sludge. The gradual release of P from sludge into the soil over time proves beneficial for plants with extended growth periods.
铝（Al）盐，特别是明矾，在混凝过程中的应用是一种广泛而常规的处理方法，用于去除废水中的污染物，包括可能导致富营养化的磷（P）。然而，该过程的一个重大挑战是会产生大量的污泥，需要进行适当的处置。历史上，土地处置是一种常见的做法，但它会对这些土地上的植物生命造成潜在问题。尽管存在相关的缺点，但污泥中含有高浓度的重要植物养分，如 P 和氮，为农业中的有益利用提供了机会。鉴于由于高品位磷矿石的最终枯竭，磷肥料即将出现短缺，本综述探讨了将铝污泥作为植物磷源的潜在优势和挑战，并提出了有益应用的措施。将铝污泥施用于土地的一个主要问题是其高浓度的可溶性 Al，已知对植物具有毒性，特别是在酸性土壤中。另一个问题是由于 Al 浓度升高导致 P 固定，从而减少植物对 P 的吸收。为了解决这些问题，可以采用石灰、石膏和有机物等土壤处理方法。此外，通过用阳离子有机聚合物替代部分铝盐来修改混凝过程，可有效降低污泥中的 Al 含量。随着时间的推移，污泥中 P 逐渐释放到土壤中，对生长周期较长的植物有益。
