Advanced Water Management Centre, The University of Queensland, St Lucia, Australia.
Water Sci Technol. 2013;67(4):756-63. doi: 10.2166/wst.2012.622.
This study aims to investigate solubilization of elements (P, N, K, Ca and Mg) during anaerobic digestion (AD) of solid agriculture waste. It is important to maintain particularly phosphorous in the aqueous phase to be able to subsequently recover it in a concentrated form via crystallization. Batch AD was carried out at a mesophilic condition (37 °C) and pH 7.0 ± 0.2 on a variety of piggery and poultry solid waste streams. Less than 10% of the total P, Ca and Mg was in soluble form in the digestate. Most of the N and K remained soluble in the digestate. A bioavailability test (citric acid extraction) showed P, Ca and Mg in the digestate were totally available. Complete solubilization of P, Ca and Mg occurred below a threshold of pH 5.5. This indicates these nutrients were released during digestion, and then either bound to form inorganic compounds or adsorbed on solid surfaces in the digestate. These effects reduce the feasibility of post-digestion recovery of the nutrients via struvite crystallization. Strategies to improve nutrient solubilization and recovery during the AD include addition of complexing chemicals, operation at depressed pH, or otherwise modifying the operating conditions.
本研究旨在探讨固体农业废弃物在厌氧消化（AD）过程中元素（P、N、K、Ca 和 Mg）的溶解情况。重要的是要保持水中磷的浓度，以便随后通过结晶以浓缩形式回收。在中温（37°C）和 pH7.0±0.2 的条件下，在各种养猪和养禽固体废物流上进行分批 AD。可溶形式存在于消化物中的总 P、Ca 和 Mg 不到 10%。大部分 N 和 K 仍可溶于消化物中。生物有效性测试（柠檬酸提取）表明消化物中的 P、Ca 和 Mg 是完全有效的。当 pH 值低于 5.5 时，P、Ca 和 Mg 完全溶解。这表明这些养分在消化过程中被释放出来，然后要么与形成无机化合物结合，要么在消化物中的固体表面上吸附。这些影响降低了通过鸟粪石结晶回收消化后养分的可行性。在 AD 过程中提高养分溶解和回收的策略包括添加络合化学品、在降低的 pH 下操作，或以其他方式改变操作条件。
