Phosphorus (P) recovered and recycled from agricultural waste, such precipitation of struvite (MgNH₄PO₄.6H₂O) and calcium phosphates from the effluent after anaerobic digestion of wastes, is an important approach to developing environmentally sustainable fertilizers. However, for controlled phosphorus precipitation/recovery, it is usually necessary to supplement Ca²⁺ or Mg²⁺ ions; this represents more than 75% of the total operational costs and, as a result, hinders a more extensive application of this process. Therefore, there is a need to investigate alternative and low-cost cation sources to recover phosphorus by precipitation. This study investigated limestone powder as calcium source and seawater as a magnesium source for phosphorus recovery by precipitation from the liquid fraction of digestate. The main parameters affecting the efficiency of the precipitation process were assessed under (i) four different pH values and (ii) three different molar ratios (Ca or Mg: P).

中文翻译：

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使用低成本离子源通过化学沉淀从液体消化物中回收磷

磷（P）回收，并从农业废弃物，鸟粪石的这种沉淀（MgNH回收₄ PO ₄ ·6H ₂ O）和磷酸钙从污水废物厌氧消化后，对发展环境可持续化肥的重要途径。然而，为了控制磷的沉淀/回收，通常需要补充 Ca ²⁺或 Mg ²⁺离子；这占总运营成本的 75% 以上，因此阻碍了该过程的更广泛应用。因此，需要研究替代和低成本的阳离子源以通过沉淀回收磷。本研究调查了石灰石粉作为钙源和海水作为镁源，通过从消化液的液体部分沉淀来回收磷。在 (i) 四种不同的 pH 值和 (ii) 三种不同的摩尔比（Ca 或 Mg: P）下评估影响沉淀过程效率的主要参数。