Transformation Kinetics of Phosphorus and Nitrogen in Iron-Rich Sewage Sludges during Hydrothermal Treatment and Recovery of Nutrients from Process Water
Transformation Kinetics of Phosphorus and Nitrogen in Iron-Rich Sewage Sludges during Hydrothermal Treatment and Recovery of Nutrients from Process Water
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DOI：
10.1021/acssuschemeng.1c03452
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发表时间：
2021-07
影响因子：
8.4
通讯作者：
Qian Wang;Haesung Jung;B. Wan;Pan Liu;Peng Yang;Yuanzhi Tang
中科院分区：
文献类型：
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作者：
Qian Wang;Haesung Jung;B. Wan;Pan Liu;Peng Yang;Yuanzhi Tang
水热处理（HT）是一种新兴的可持续污水污泥管理和资源回收技术。由于在水资源回收设施中通常添加铁盐，许多污泥富含铁（Fe）。为指导以养分回收为目标的反应条件，系统研究了高温处理温度、处理时间和污泥来源对富铁污泥高温处理过程中磷（P）和氮（N）形态变化的影响。进行了补充化学提取和X射线光谱分析以表征处理产物。对于污泥混合物（初级和废物活性污泥的混合物），P形态在125 ° C HT下4.5小时内没有显著变化，而可溶性和不稳定的P在175和225 ° C HT下随着时间的推移转化为不溶性P。随着热处理温度和时间的增加，水焦中优先生成铁磷钙石（FePO 4 ·2 H2O），而125 ° C热处理1.5h有利于生成蓝铁矿（Fe 3（PO 4）2 · 8H 2 O）。当热处理温度达到175 ° C时，有机磷完全分解为正磷酸盐。吡咯-N在氢焦中富集。在厌氧消化污泥的HT过程中观察到类似的反应途径，虽然在铁相关的P和有机P的一些轻微的差异进行了观察。同时，在175和225 ° C下，两种污泥的高温释放正磷酸盐和氨到工艺沃茨中，其可通过鸟粪石（MgNH 4PO 4 ·6 H2O）沉淀和空气吹脱的顺序过程回收。该研究为富铁污泥高温处理期间P和N的转化提供了新的见解，并提供了模块化设计，以最大限度地从处理产品中回收P和N。
: Hydrothermal treatment (HT) is an emerging technique for sustainable sewage sludge management and resource recovery. Many sludges are rich in iron (Fe) due to the common addition of Fe salts in water resource recovery facilities. To develop guidance for reaction conditions targeting nutrient recovery, this study systematically investigated the in fl uence of HT temperature, treatment time, and sludge source on the dynamic speciation evolution of phosphorus (P) and nitrogen (N) during HT of Fe-rich sewage sludge. Complementary chemical extraction and X-ray spectroscopy analyses were conducted to characterize the treat-ment products. For the sludge mixture (a blend of primary and waste activated sludges), P speciation did not change signi fi cantly within 4.5 h at 125 ° C HT, while soluble and labile P was converted into insoluble P over time at 175 and 225 ° C HT. Strengite (FePO 4 · 2H 2 O) preferentially formed in the hydrochars with increasing treatment temperature and/or time, whereas 125 ° C HT within 1.5 h favored the formation of vivianite (Fe 3 (PO 4 ) 2 · 8H 2 O). Organic P was completely decomposed into orthophosphate when the HT temperature reached up to 175 ° C. Pyrrole-N was enriched in the hydrochars. Similar reaction pathways were observed during HT of anaerobically digested sludge, though some minor di ff erences in Fe-associated P and organic P were observed. Meanwhile, HT of the two sludges released orthophosphate and ammonia into the process waters at 175 and 225 ° C, which can be recovered by a sequential process involving struvite (MgNH 4 PO 4 · 6H 2 O) precipitation and air stripping. This study provides new insights into the transformation of P and N during HT of Fe-rich sludges as well as a modular design for maximum P and N recovery from the treatment products.