This study characterises the sewage sludge from 26 sewage treatment plants in India, which demonstrates the nutrient potential and highlights the associated challenges in using the sludge. The dry sludge had 2.35%–4.2% N, 2.46–3.2% phosphorus (P₂O₅) and 0.83%–1.24% potassium oxide (K₂O), whereas sludge ash contains ~13.6% and 2.7%, P₂O₅ and K₂O, respectively. Total nutrient potential from the sludge of the existing sewage treatment facility was 97.5 × 10³ tonne/year, which is equivalent to 0.92% urea or 0.19% NPK used presently as conventional fertilisers in India. However, pre-treatment may be required for this sludge before using it in agricultural fields as heavy metals, such as Zn, Cu, Ni, Cd, and Cr, were found higher than the compost standards. This study would be useful for the researchers and policymakers globally and would motivate them to make policies and deploy suitable technologies towards the nutrient utilisation from sewage sludge.

中文翻译：

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释放污水污泥的营养价值

本研究对来自印度 26 家污水处理厂的污水污泥进行了表征，展示了其营养潜力并突出了使用污泥的相关挑战。干污泥含有 2.35%–4.2% 的 N、2.46–3.2% 的磷 (P ₂ O ₅ ) 和 0.83%–1.24% 的氧化钾 (K ₂ O)，而污泥灰分含有约 13.6% 和 2.7% 的 P ₂ O分别为₅和 K ₂ O。现有污水处理设施污泥的总养分潜力为 97.5 × 10 ³吨/年，相当于印度目前用作常规肥料的 0.92% 尿素或 0.19% NPK。然而，由于发现重金属（如锌、铜、镍、镉和铬）高于堆肥标准，因此在将其用于农田之前可能需要对这种污泥进行预处理。这项研究将对全球的研究人员和政策制定者有用，并将激励他们制定政策并部署合适的技术来利用污水污泥中的养分。