Environmentally-friendly dewatering of sewage sludge: A novel strategy based on amphiphilic phase-transfer induced by recoverable organic solvent
Environmentally-friendly dewatering of sewage sludge: A novel strategy based on amphiphilic phase-transfer induced by recoverable organic solvent
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DOI：
10.1016/j.cej.2020.128212
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发表时间：
2021-04
影响因子：
15.1
通讯作者：
Boran Wu;Hao Wang;Chengxian Wang;Xiaohu Dai;Xiaoli Chai
中科院分区：
文献类型：
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作者：
Boran Wu;Hao Wang;Chengxian Wang;Xiaohu Dai;Xiaoli Chai
本研究提出了一种通过调节液相的极性来消除固液亲和力来改善污泥脱水性能的新策略。不同有机改性剂(如极性溶剂、低极性溶剂、溶细胞剂)的初步筛选实验发现，在溶剂与污泥质量比为1：1时，乙腈和丙酮可使污泥的过滤比阻力分别降低83.9%和76.8%。同时，综合考虑进料加热的显热和溶剂的挥发热，在相同处理量的条件下，乙腈/丙酮强化污泥脱水工艺的理论能耗至少比热干法低1/3以上，表明了溶剂强化污泥脱水工艺的节能潜力。利用高分辨傅里叶变换离子回旋共振质谱仪分析了残留固相表面官能团和两亲化合物的相转移特性，并对反应机理进行了研究。研究发现，液相的极性对污泥组分的相转移起主导作用。液体极性的充分降低(介电常数为55)将显著消除极性官能团与低极性液相的亲和力，从而诱导两亲性蛋白质的沉淀，大大加强固液分离。这些发现表明，通过改变液相的物理性质来改善污泥的脱水性能是一种很有前途的技术，在节能降耗方面显示出明显的优势。
This study proposed a novel strategy for sludge dewaterability improvement by eliminating the solid-liquid affinity through the polarity regulation of liquid phase. Initial screening experiments with different types of organic amendments (e.g., polar solvents, low-pole solvents, cytolytic reagents) found that acetonitrile and acetone could reduce specific resistance to filtration of sludge by 83.9% and 76.8%, respectively, at the solvent-sludge mass ratio of 1:1. The vacuum distillation and atmospheric distillation were both examined for the solvent recovery from filtered sludge cake and filtrate. Also, by considering the sensible heat for feedstock heating and enthalpy of solvent evaporation, the theoretical energy consumption of acetonitrile/acetone-enhanced sludge dewatering process was estimated to be at least 1/3 lower than that of the thermal drying process with the same treatment capacity, which indicated the energy saving potential of solvent-enhanced sludge dewatering process. Mechanism investigation was conducted by analyzing the surface functional groups of residual solid phase and the phase-transfer characteristics of amphiphilic compounds based on high-resolution Fourier transform-ion cyclotron resonance-mass spectrometry. It was found that the polarity of liquid phase dominated the phase-transfer of sludge compositions. The sufficient decrease in liquid polarity (dielectric constant < 55) would significantly eliminate the affinity of polar functional groups with the low-pole liquid phases, which induced the precipitation of amphiphilic proteins and substantially enhanced the solid-liquid separation. These findings suggest a promising technology for sludge dewaterability improvement by modifying the physical properties of liquid phase, which exhibits the obvious advantages in saving energy and material consumption.