School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093, PR China.
School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai, 200093, PR China; School of Environment Engineering, Shanghai Jiao Tong University, Shanghai, 200240, PR China.
Environ Res. 2022 Nov;214(Pt 3):113974. doi: 10.1016/j.envres.2022.113974. Epub 2022 Aug 8.
The addition of sludge-based biochar during electrochemical pretreatment of sewage sludge, as an efficient hybrid technology, is potentially to be applied in sludge deep-dewatering. The chars functioned as conductors, catalysts and skeleton particles could enhance the sludge dewaterability and increase the calorific value of the dewatered sludge cake. However, the effect of synthesis conditions on the char properties and further on the dewatering performance is still unknown. Herein, the sludge-based particle electrodes (SPEs) under three main synthesis conditions, including liquid-solid ratio, pyrolysis temperature and time, were prepared. The sludge-based biochars (i.e., SPE-400, SPE-600, and SPE-800 pyrolyzed under 400, 600 and 800 °C, respectively) were characterized and utilized as three-dimensional electrodes during sludge electrolysis. The increased pyrolysis temperature (within 400-800 °C) resulted in the enrichment of metallic ions and increment of specific surface area and pore volume of SPE, which led to the increased catalysis and adsorption sites for viscous proteins (PNs). Particularly, the pores of SPE-800 provided more drainage channels as skeleton builders. Compared with raw sludge, the capillary suction time (CST) and the specific resistance of filtration (SRF) of the treated sludge with 3D-SPE-800 were reduced by 58.12% and 81.01%, respectively, but the net sludge solids yield (Y) was increased by 87.05%. The highest decrease of hydrophilic α-Helix content in PNs (from 9.93% to 7.30%) was observed when using SPE-800 as particle electrode, revealing the crucial role of char characteristics on protein reduction and subsequent dewatering enhancement. The synergistic effects of electrolysis and sludge-based biochar provided a new insight for a closed-loop pretreatment of sewage sludge in the wastewater treatment plant.
在污水污泥电化学预处理过程中添加基于污泥的生物炭作为一种有效的混合技术，具有在污泥深度脱水中的应用潜力。作为导体、催化剂和骨架颗粒的炭可以提高污泥的脱水性能并增加脱水污泥饼的热值。然而，合成条件对炭特性以及进一步对脱水性能的影响仍然未知。在此，在三种主要的合成条件下制备了基于污泥的颗粒电极（SPE），包括固液比、热解温度和时间。分别在 400、600 和 800°C 下热解的基于污泥的生物炭（即 SPE-400、SPE-600 和 SPE-800）进行了表征，并用作污泥电解的三维电极。增加的热解温度（400-800°C 范围内）导致金属离子的富集和比表面积和孔体积的增加，从而增加了粘性蛋白（PN）的催化和吸附位点。特别是 SPE-800 的孔提供了更多的排水通道作为骨架构建体。与原始污泥相比，用 3D-SPE-800 处理的污泥的毛细抽吸时间（CST）和过滤比阻（SRF）分别降低了 58.12%和 81.01%，但净污泥固体产率（Y）增加了 87.05%。当使用 SPE-800 作为颗粒电极时，PN 中亲水性α-螺旋含量（从 9.93%降至 7.30%）的降低幅度最大，表明炭特性对蛋白质减少和随后的脱水增强起着关键作用。电解和基于污泥的生物炭的协同作用为污水处理厂中污水污泥的闭环预处理提供了新的思路。
