Gumisiriza Robert, Hawumba Joseph Funa, Okure Mackay, Hensel Oliver
School of Biosciences, Makerere University, P.O Box 7062, Kampala, Uganda.
School of Engineering, Makerere University, P.O Box 7062, Kampala, Uganda.
Biotechnol Biofuels. 2017 Jan 3;10:11. doi: 10.1186/s13068-016-0689-5. eCollection 2017.
Uganda's banana industry is heavily impeded by the lack of cheap, reliable and sustainable energy mainly needed for processing of banana fruit into pulp and subsequent drying into chips before milling into banana flour that has several uses in the bakery industry, among others. Uganda has one of the lowest electricity access levels, estimated at only 2-3% in rural areas where most of the banana growing is located. In addition, most banana farmers have limited financial capacity to access modern solar energy technologies that can generate sufficient energy for industrial processing. Besides energy scarcity and unreliability, banana production, marketing and industrial processing generate large quantities of organic wastes that are disposed of majorly by unregulated dumping in places such as swamps, thereby forming huge putrefying biomass that emit green house gases (methane and carbon dioxide). On the other hand, the energy content of banana waste, if harnessed through appropriate waste-to-energy technologies, would not only solve the energy requirement for processing of banana pulp, but would also offer an additional benefit of avoiding fossil fuels through the use of renewable energy.
The potential waste-to-energy technologies that can be used in valorisation of banana waste can be grouped into three: Thermal (Direct combustion and Incineration), Thermo-chemical (Torrefaction, Plasma treatment, Gasification and Pyrolysis) and Biochemical (Composting, Ethanol fermentation and Anaerobic Digestion). However, due to high moisture content of banana waste, direct application of either thermal or thermo-chemical waste-to-energy technologies is challenging. Although, supercritical water gasification does not require drying of feedstock beforehand and can be a promising thermo-chemical technology for gasification of wet biomass such as banana waste, it is an expensive technology that may not be adopted by banana farmers in Uganda. Biochemical conversion technologies are reported to be more eco-friendly and appropriate for waste biomass with high moisture content such as banana waste.
Uganda's banana industrialisation is rural based with limited technical knowledge and economic capability to setup modern solar technologies and thermo-conversions for drying banana fruit pulp. This review explored the advantages of various waste-to-energy technologies as well as their shortfalls. Anaerobic digestion stands out as the most feasible and appropriate waste-to-energy technology for solving the energy scarcity and waste burden in banana industry. Finally, potential options for the enhancement of anaerobic digestion of banana waste were also elucidated.
乌干达的香蕉产业受到严重阻碍，主要原因是缺乏廉价、可靠且可持续的能源，而这些能源是将香蕉果实加工成果浆，并随后干燥制成薯片，最后研磨成香蕉粉（在烘焙行业等有多种用途）所必需的。乌干达的电力接入水平极低，在大多数香蕉种植所在的农村地区，估计仅为2%至3%。此外，大多数香蕉种植户的经济能力有限，无法获取能为工业加工产生足够能源的现代太阳能技术。除了能源稀缺和不可靠之外，香蕉生产、销售和工业加工还会产生大量有机废物，这些废物主要通过在沼泽等地无管制倾倒的方式进行处理，从而形成大量散发温室气体（甲烷和二氧化碳）的腐烂生物质。另一方面，如果通过适当的废物转化能源技术来利用香蕉废物的能量，不仅可以解决香蕉果浆加工的能源需求，还能通过使用可再生能源带来避免使用化石燃料的额外好处。
可用于香蕉废物增值的潜在废物转化能源技术可分为三类：热（直接燃烧和焚烧）、热化学（烘焙、等离子体处理、气化和热解）和生物化学（堆肥、乙醇发酵和厌氧消化）。然而，由于香蕉废物的含水量高，直接应用热或热化学废物转化能源技术具有挑战性。尽管超临界水气化不需要预先干燥原料，并且可能是一种用于气化香蕉废物等湿生物质的有前景的热化学技术，但它是一种昂贵的技术，乌干达的香蕉种植户可能不会采用。据报道，生物化学转化技术更环保，适合处理含水量高的废物生物质，如香蕉废物。
乌干达的香蕉产业化以农村为基础，在建立现代太阳能技术和用于干燥香蕉果浆的热转化方面技术知识和经济能力有限。本综述探讨了各种废物转化能源技术的优点及其不足。厌氧消化是解决香蕉产业能源短缺和废物负担最可行、最合适的废物转化能源技术。最后，还阐明了增强香蕉废物厌氧消化的潜在选择。
