Usack Joseph G, Spirito Catherine M, Angenent Largus T
Department of Biological and Environmental Engineering, Cornell University.
J Vis Exp. 2012 Jul 13(65):e3978. doi: 10.3791/3978.
Anaerobic digestion (AD) is a bioprocess that is commonly used to convert complex organic wastes into a useful biogas with methane as the energy carrier. Increasingly, AD is being used in industrial, agricultural, and municipal waste(water) treatment applications. The use of AD technology allows plant operators to reduce waste disposal costs and offset energy utility expenses. In addition to treating organic wastes, energy crops are being converted into the energy carrier methane. As the application of AD technology broadens for the treatment of new substrates and co-substrate mixtures, so does the demand for a reliable testing methodology at the pilot- and laboratory-scale. Anaerobic digestion systems have a variety of configurations, including the continuously stirred tank reactor (CSTR), plug flow (PF), and anaerobic sequencing batch reactor (ASBR) configurations. The CSTR is frequently used in research due to its simplicity in design and operation, but also for its advantages in experimentation. Compared to other configurations, the CSTR provides greater uniformity of system parameters, such as temperature, mixing, chemical concentration, and substrate concentration. Ultimately, when designing a full-scale reactor, the optimum reactor configuration will depend on the character of a given substrate among many other nontechnical considerations. However, all configurations share fundamental design features and operating parameters that render the CSTR appropriate for most preliminary assessments. If researchers and engineers use an influent stream with relatively high concentrations of solids, then lab-scale bioreactor configurations cannot be fed continuously due to plugging problems of lab-scale pumps with solids or settling of solids in tubing. For that scenario with continuous mixing requirements, lab-scale bioreactors are fed periodically and we refer to such configurations as continuously stirred anaerobic digesters (CSADs). This article presents a general methodology for constructing, inoculating, operating, and monitoring a CSAD system for the purpose of testing the suitability of a given organic substrate for long-term anaerobic digestion. The construction section of this article will cover building the lab-scale reactor system. The inoculation section will explain how to create an anaerobic environment suitable for seeding with an active methanogenic inoculum. The operating section will cover operation, maintenance, and troubleshooting. The monitoring section will introduce testing protocols using standard analyses. The use of these measures is necessary for reliable experimental assessments of substrate suitability for AD. This protocol should provide greater protection against a common mistake made in AD studies, which is to conclude that reactor failure was caused by the substrate in use, when really it was improper user operation.
厌氧消化（AD）是一种生物过程，通常用于将复杂的有机废物转化为以甲烷为能量载体的有用沼气。越来越多的厌氧消化技术被应用于工业、农业和城市垃圾（污水）处理领域。使用厌氧消化技术可使工厂运营者降低废物处理成本并抵消能源费用。除了处理有机废物外，能源作物也正被转化为能量载体甲烷。随着厌氧消化技术在处理新底物和共底物混合物方面的应用不断拓展，对中试和实验室规模可靠测试方法的需求也与日俱增。厌氧消化系统有多种配置，包括连续搅拌槽式反应器（CSTR）、推流式（PF）和厌氧序批式反应器（ASBR）配置。由于设计和操作简单，且在实验方面具有优势，CSTR常用于研究中。与其他配置相比，CSTR能使系统参数（如温度、混合、化学物质浓度和底物浓度）具有更高的均匀性。最终，在设计全尺寸反应器时，最佳反应器配置将取决于给定底物的特性以及许多其他非技术因素。然而，所有配置都具有基本的设计特征和操作参数，这使得CSTR适用于大多数初步评估。如果研究人员和工程师使用固体浓度相对较高的进水水流，那么实验室规模的生物反应器配置由于实验室规模的泵被固体堵塞或固体在管道中沉降的问题而无法连续进料。对于有连续混合要求的这种情况，实验室规模的生物反应器需定期进料，我们将这种配置称为连续搅拌厌氧消化器（CSAD）。本文介绍了一种构建、接种、操作和监测CSAD系统的通用方法，目的是测试给定有机底物对长期厌氧消化的适用性。本文的构建部分将涵盖实验室规模反应器系统的搭建。接种部分将解释如何创建适合用活性产甲烷接种物接种的厌氧环境。操作部分将涵盖操作、维护和故障排除。监测部分将介绍使用标准分析方法的测试方案。使用这些措施对于可靠地实验评估底物对厌氧消化的适用性是必要的。该方案应能更好地防止厌氧消化研究中常见的错误，即当实际上是用户操作不当导致反应器故障时，却得出是所用底物导致反应器故障的结论。
