Abstract:

Under the background of "carbon neutralization", sludge treatment and disposal is an important field of emission reduction. Anaerobic digestion is one of the key technologies of sludge safety disposal and energy recovery. As a low-carbon technology, the carbon emission of anaerobic digestion is mainly the result of the balance between the "energy source carbon emission" produced by energy consumption in the process of treatment and the "carbon compensation" formed by biomass energy (such as methane) produced after treatment and disposal. Therefore, reducing energy consumption and improving methane production are the main ideas to realize "carbon neutralization". Thermal, chemical, and mechanical pretreatment are effective means to break the rate-limiting hydrolysis of anaerobic digestion, mainly focusing on increasing methane production to form more "carbon compensation". However, from the perspective of thermodynamics, pretreatment is the process of dissolving a large amount of organic matter through the consumption of electric, heat, and chemical energy, thereby obtaining more biomass energy. As an energy input form, pretreatment increases the energy consumption of anaerobic digestion. The inhibitory factors produced in the process prevent the solubilized organic matter from being completely converted into methane. Increasing methane production is usually difficult to balance this part of the energy consumption. Therefore, the selection of low energy consumption pretreatment methods can effectively reduce carbon emissions. Previous studies usually used methane production as the evaluation index of anaerobic digestion performance, which was difficult to objectively evaluate the actual benefits of various anaerobic digestion pretreatments. In this paper, the mechanism of various sludge pretreatment methods and their inhibitory factors on anaerobic digestion were reviewed. The research results of typical thermal pretreatment, alkali pretreatment, ultrasonic pretreatment and combined treatment on methane production, net energy and net profit were compared. Based on the evaluation of anaerobic digestion efficiency of sludge, the feasibility of the above pretreatment methods at the energy and economic levels was analyzed, which provides multi-dimensional basis for the selection of pretreatment methods and intensity.

Key words: net energy production, net cost, anaerobic digestion pretreatment, inhibitor, energy economy

摘要：

在污泥的厌氧消化中，降低过程能耗与提高甲烷产量是实现污水处理系统“碳中和”的主要思路之一。热、化学、机械预处理是打破厌氧消化限速水解的有效手段，主要着眼于甲烷增产以形成更多的“碳补偿”。但从热力学角度，预处理是通过消耗电能、热能、化学能使有机物大量溶解，从而获得更多生物质能的过程，其本身作为一种能量输入形式增加了厌氧消化的能耗。以往的研究通常以污泥液相中有机物溶出、固相中有机物去除以及甲烷产量作为厌氧消化性能的评价指标，难以客观评估各类厌氧消化预处理的实际效益。本文从能源转换的角度出发，综述了各类污泥预处理方法的作用机理及对厌氧消化的抑制因子等方面的研究进展，对比了典型的热预处理、碱预处理、超声预处理及其联合处理分别在甲烷产量、净能量和净利润等指标上的研究结果，并在污泥厌氧消化效率评价基础上分析了上述预处理方法在能源和经济层面的可行性，为预处理方法和预处理条件的选择提供多维度依据。

关键词: 净能量, 净利润, 厌氧消化预处理, 抑制因子, 能源经济性