Three Birds with One Stone: N/P Recovery, Dewaterability Improvement, and Facilitating Liquid Digestate Treatment of Anaerobically Digested Sludge
Three Birds with One Stone: N/P Recovery, Dewaterability Improvement, and Facilitating Liquid Digestate Treatment of Anaerobically Digested Sludge
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DOI：
10.1021/acssuschemeng.2c03863
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发表时间：
2022-09
期刊：
影响因子：
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通讯作者：
Boran Wu;Hewei Li;Kun Zhou;Xiaoli Chai;Xiaohu Dai
中科院分区：
文献类型：
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作者：
Boran Wu;Hewei Li;Kun Zhou;Xiaoli Chai;Xiaohu Dai
为提高厌氧消化污泥的资源化价值，本研究开发了一种结合营养物质回收的新型脱水工艺。多电荷阴离子的水化被认为与亲水性有机成分的水化竞争(即盐析效应)。因此，采用磷酸盐作为盐析剂来改善污泥的脱水性能，同时平衡了水相中NH4+-N和PO43--P的摩尔比，有利于从液体沼液中回收鸟粪石形式的N/P。在污泥初始pH为5时投加70%的磷酸盐，可获得最低的离心脱水平衡高度(h∞)为0.036 cm，结合水含量降低63.5%。首次采用飞行时间二次离子质谱仪(ToF-SIMS)对厌氧消化污泥中磷的形态和微观分布进行了原位鉴定。此外，石英晶体耗散微天平(QCM-D)分析证实，有机物-磷酸盐的相互作用导致污泥絮体形成致密的拒水系统，硬度增加，这主要是提高离心式脱水性能的主要原因。上述研究成果有望为同时回收N/P、改善脱水性能和促进厌氧消化污泥的液体消化处理提供一条有希望的途径。
This study developed a novel dewatering process coupled with nutrient recovery to raise the resource value of anaerobically digested sludge. The hydration of multicharged anions was proposed to compete with the hydration of hydrophilic organic components (i.e., salting-out effects). Accordingly, phosphate was used as the salting-out agent to improve sludge dewaterability, and simultaneously, it balanced the molar ratio of NH4+-N and PO43–-P in the aqueous phase, which could facilitate the recovery of N/P as struvite from the liquid digestate. The addition of phosphate (70% of its solubility) at the initial sludge pH of 5 could obtain the lowest centrifugally dewatering equilibrium height (h∞) of 0.036 cm and reduce the bound water fraction by 63.5%. For the first time, time-of-flight secondary ion mass spectrometry (ToF-SIMS) in situ identified the phosphorus speciation and microdistribution in anaerobically digested sludge. Additionally, the quartz crystal microbalance with dissipation (QCM-D) analysis confirmed that the organics-phosphate interactions led to a dense water-repelling system of sludge flocs with an increasing rigidity, which mainly contributed to the improved centrifugal dewatering performance. All the above contributions are expected to suggest a promising way for simultaneously recovering N/P, improving dewaterability, and facilitating liquid digestate treatment of anaerobically digested sludge.