Abstract

Two-stage anaerobic reactors are being widely used in the organic waste management industry. In these reactors, up to one-third of the chemical oxygen demand (COD) content is naturally pre-acidified in a first stage pre-acidification (PA) and then fed to a second stage digester for conversion to methane. Traditionally, all the generated gases from the PA tank will be vented to the atmosphere. Hydrogen and carbon dioxide are the main gases generated in the PA tank. A pilot-scale of two-stage anaerobic expanded granular sludge bed reactor was fabricated and used to investigate the impact of the PA gas injection into the second stage. The gas from the PA reactor was captured and stored in the storage tank. The tests were run under two temperature ranges and five organic loading rates (∼2, 3, 4, 5, and 6 g COD/L.day). For mesophilic range, the biogas production and energy yield increased by 10–90% and 40–130%, respectively, from without PA gas injection case compared to with PA injection case. For thermophilic range, the biogas production and energy yield increased by 12–40% and 90–140%, respectively, from without PA gas injection compared to with PA injection case. For each OLR, the gas production and energy yield were 90 to 160% more in thermophilic range than the mesophilic range for the cases with and without the PA gas injection. This implies that a higher temperature range has a significant impact on energy yield in a digester. One of the important findings was the amount of the PA gas injected into the EGSB reactor should be less than 50% of the theoretically calculated hydrogen gas based on ethanol substrate assumption.

摘要

两级厌氧反应器广泛用于有机废物管理行业。在这些反应器中，多达三分之一的化学需氧量 (COD) 在第一阶段预酸化 (PA) 中自然预酸化，然后送入第二阶段消化器以转化为甲烷。传统上，PA 罐产生的所有气体都将排放到大气中。氢气和二氧化碳是 PA 罐中产生的主要气体。制造了一个中试规模的两级厌氧膨胀颗粒污泥床反应器，并用于研究 PA 气体注入第二阶段的影响。来自 PA 反应器的气体被捕获并储存在储罐中。测试在两个温度范围和五个有机负载率（~2、3、4、5 和 6 g COD/L.day）下进行。对于中温范围，与注入 PA 的情况相比，没有 PA 气体注入的情况下，沼气产量和能源产量分别提高了 10-90% 和 40-130%。对于嗜热范围，与注入 PA 的情况相比，没有 PA 气体注入的沼气产量和能源产量分别增加了 12-40% 和 90-140%。对于每个 OLR，在有和没有 PA 气体注入的情况下，高温范围内的气体产量和能量产量比中温范围高 90% 至 160%。这意味着较高的温度范围对蒸煮器中的能量产量具有显着影响。其中一项重要发现是注入 EGSB 反应器的 PA 气体量应小于基于乙醇底物假设的理论计算氢气的 50%。