Liu Zhiguo, Liao Wei, Liu Yan
Department of Biosystems and Agricultural Engineering, Michigan State University, 524 S. Shaw Ln. Room 203, East Lansing, MI 48824-1323 USA.
Biotechnol Biofuels. 2016 Sep 17;9:197. doi: 10.1186/s13068-016-0609-8. eCollection 2016.
Animal wastes are of particular environmental concern due to greenhouse gases emissions, odor problem, and potential water contamination. Anaerobic digestion (AD) is an effective and widely used technology to treat them for bioenergy production. However, the sustainability of AD is compromised by two by-products of the nutrient-rich liquid digestate and the fiber-rich solid digestate. To overcome these limitations, this paper demonstrates a biorefinery concept to fully utilize animal wastes and create a new value-added route for animal waste management.
The studied biorefinery includes an AD, electrocoagulation (EC) treatment of the liquid digestate, and fungal conversion of the solid fiber into a fine chemical-chitin. Animal wastes were first treated by an AD to produce methane gas for energy generation to power the entire biorefinery. The resulting liquid digestate was treated by EC to reclaim water. Enzymatic hydrolysis and fungal fermentation were then applied on the cellulose-rich solid digestate to produce chitin. EC water was used as the processing water for the fungal fermentation. The results indicate that the studied biorefinery converts 1 kg dry animal wastes into 17 g fungal biomass containing 12 % of chitin (10 % of glucosamine), and generates 1.7 MJ renewable energy and 8.5 kg irrigation water.
This study demonstrates an energy positive and freshwater-free biorefinery to simultaneously treat animal wastes and produce a fine chemical-chitin. The sustainable biorefinery concept provides a win-win solution for agricultural waste management and value-added chemical production.
由于温室气体排放、气味问题以及潜在的水污染，动物粪便引起了特别的环境关注。厌氧消化（AD）是一种有效且广泛应用的处理动物粪便以生产生物能源的技术。然而，AD的可持续性受到富含营养的液体沼液和富含纤维的固体沼渣这两种副产品的影响。为克服这些限制，本文展示了一种生物精炼概念，以充分利用动物粪便，并为动物粪便管理创造一条新的增值途径。
所研究的生物精炼过程包括厌氧消化、对液体沼液进行电凝聚（EC）处理以及将固体纤维真菌转化为精细化学品——几丁质。动物粪便首先通过厌氧消化产生甲烷气体用于能源生产，为整个生物精炼过程提供动力。产生的液体沼液通过电凝聚处理以回收水。然后对富含纤维素的固体沼渣进行酶水解和真菌发酵以生产几丁质。电凝聚处理后的水用作真菌发酵的加工用水。结果表明，所研究的生物精炼过程可将1千克干动物粪便转化为17克含12%几丁质（10%氨基葡萄糖）的真菌生物质，并产生1.7兆焦耳可再生能源和8.5千克灌溉用水。
本研究展示了一种能源正向且无需淡水的生物精炼过程，可同时处理动物粪便并生产精细化学品——几丁质。这种可持续的生物精炼概念为农业废弃物管理和增值化学品生产提供了双赢解决方案。
