垃圾发电厂渗滤液UASB系统管路结垢特征及生成机制
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X799.3

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国家重点研发计划(2020YFC1908600, 2020YFC1908602)


Characteristics and formation mechanism of pipeline scaling minerals in the UASB anaerobic fermentation system of leachate from waste-to-energy plants
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    摘要:

    升流式厌氧污泥反应器(UASB)处理垃圾渗滤液过程中,微生物矿化产物会在循环管路、沼液排出管路沉积造成管路堵塞。频繁更换管路来清除堵塞的方法劳动强度大,而且影响系统稳定运行。本文利用矿物学表征方法研究UASB系统管路结垢的矿物学和微观结构特征,探讨管路结垢形成机制,为UASB反应器管路阻垢、抑垢以及管路结垢清洗提供理论依据。结果表明:管路结垢为微生物矿化产物夹杂有机物的复合体,基本为酸可溶物,主要结晶物相为单水方解石和鸟粪石,夹杂少量方解石;鸟粪石主要呈直径0.2~0.5 mm的柱状晶体,束状、放射状排列,单水方解石呈50~350 nm球形颗粒。垃圾渗滤液在厌氧产甲烷过程中同步消耗H+、生成大量的CO2,提高了沼液的碳酸根浓度,同时完成有机氮氨化、有机磷磷酸盐化过程。沼液中磷、镁、铵结合结晶出鸟粪石,钙离子和碳酸根结合结晶出碳酸盐矿物。虽然沼液中离子浓度对磷灰石过饱和,但沼液中镁离子和高浓度有机物可能抑制了它的成核和结晶生长。UASB系统中鸟粪石首先在管路表面异相成核并生长成粗大柱状晶体,单水方解石与少量有机物填充鸟粪石间空隙,从而胶结形成了具有一定强度、耐流体冲刷的管壁结垢。考虑采用5%醋酸原位酸溶方法清除管路结垢,使酸洗管路的残液酸度尽可能低,不改变大型UASB反应器内液体的pH值,还可以作为产甲烷菌底物利用提高甲烷产量。

    Abstract:

    In the process of treating landfill leachate using the upflow anaerobic sludge blanket (UASB), microbial mineralization products can deposit and block the circulation and effluent pipes. Repeatedly replacing pipes to remove blockages is a labor-intensive process and exerts a negative impact on the stable operation of the system. The mineralogy and microscopic structural features of scaling in UASB system pipelines were investigated by mineralogical characterization methods in this study. The mechanism of scaling formation was explored. It provides a theoretical foundation for the prevention, inhibition, and cleaning of scaling in UASB reactor pipelines. The results indicated that the pipe scaling constituted a complex mixture of microbial mineralization products and organic matter, primarily consisting of acid-soluble materials. The main crystalline phases were monohydrocalcite and struvite. Struvite presented columnar crystals with diameters ranging from 0.2 nm to 0.5 mm, and arranged in bundles or radiating patterns. Monohydrocalcite appeared as spherical particles with diameters ranging from 50 nm to 350 nm. The anaerobic process producing methane production of landfill leachate consumed H+ and generated a large amount of CO2, which increased the carbonate alkalinity of the anaerobic digestate. Meanwhile, organic nitrogen was ammonified, and organic phosphorus was converted into phosphate. In the digestion, phosphate, magnesium, and ammonium ions combine to crystallize into struvite, while calcium ions and carbonate ions combine to crystallize into calcite. Although the ion concentrations in the anaerobic digestate were supersaturated for hydroxyapatite and calcite, the presence of magnesium ions and high concentrations of organic matter in the anaerobic digestate may inhibit their nucleation and crystal growth. In the UASB system, struvite undergoes heterogeneous nucleation on the pipeline surface, growing into large columnar crystals. Monohydrocalcite filled the gaps between struvite crystals, incorporating a small amount of organic matter. Then, struvite and calcium carbonate were cemented together, forming pipe scaling with a certain level of strength resisting to fluid flushing. Considering the use of an in-situ acid dissolution method with 5% acetic acid to remove pipe scale, the residual acidity of the acid wash solution will keep as low as possible without altering the pH of the liquid inside the large-scale UASB reactor. Additionally, Low concentration acetic acid can serve as a substrate for methane-producing bacteria to enhance methane production.

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戴蓝兰,刘晓吉,黄智,等, 2025. 垃圾发电厂渗滤液UASB系统管路结垢特征及生成机制[J]. 岩石矿物学杂志, 44(2):463~472.
DAI Lan-lan, LIU Xiao-ji, HUANG Zhi, et al, 2025. Characteristics and formation mechanism of pipeline scaling minerals in the UASB anaerobic fermentation system of leachate from waste-to-energy plants[J]. Acta Petrologica et Mineralogica, 44(2): 463~472.

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  • 收稿日期:2024-03-27
  • 最后修改日期:2024-12-04
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  • 在线发布日期: 2025-03-31
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