Enhancing the Methane Generation from Food Waste Anaerobic Digestion Mediated by Fluidic Oscillator Generated Microbubbles

作为一个文明，我们每年产生超过20亿吨的食物垃圾，其中大部分可以通过适当的处理以可持续的方式利用AD作为能源。欧盟，英国是主要的罪犯，每年产生超过89吨的食物垃圾。作为第一步，这些废物可以作为动物的食物来源重新分配，但如果失败，最好使用AD回收能量。AD代表营养回收，是2015年上议院关于食物垃圾的报告中讨论的废弃食物等级所规定的所有其他废物管理手段的首选方案。AD是一种在厌氧（不存在空气）条件下通过将高级链化合物分解成甲烷和其他低级链化合物来将食物垃圾或生物质或粪肥转化的过程。该方法通常遵循以下步骤：将生物质（湿食物垃圾）放入密封的气密容器2中。使用系统中存在的厌氧微生物消化该生物质（湿食物垃圾）以产生用于能量产生的富含甲烷的生物气3。我们提出的途径是用流体振荡的富含CO2的微泡代替密闭容器，该微泡通过使用CaCaCa工艺[1]和微泡技术[2-5]现场脱硫烟道气而获得。与常规方法相比，富CO2微泡的周期性注入（5分钟）显示出增加CH 4产量110%。这是一个双管齐下的过程，通过微泡汽提和同时注入营养物来去除代谢物/废物。所产生的甲烷可用于发电，从而抵消化石燃料的使用并减少温室气体（GHG）排放。我们通过使用CaCaCa工艺使沼气脱硫来获得富含CO2的微泡，以便捕获然后燃烧的CH 4，并且烟道气富含CO2（可能含有易于冷凝的水蒸气）。这是进一步自维持的，因为在第一步骤中产生的CH 4的燃烧导致烟道气的产生。用于产生微泡的流体振荡器支持脱硫和产甲烷（AD中的过程，其中产生甲烷）。这大大增加了AD中形成的产品的价值，同时消耗了产生的二氧化碳，从而进一步抵消了温室气体排放。从过程中回收热量增加了这种能量平衡，可用于通过热电联产（CHP）进行现场加热。该项目将研究这种新型流体振荡富CO2微泡工艺的现场原型构建，用于AD和使用Perlemax的流体振荡器驱动微泡优化的CaCaCa工艺产生的烟气的同时脱硫。CHP和CH 4的生成量可以通过优化工艺变量进一步增加，如图2所示。这可能会使CH 4生成量超过预定的110%。这确保了碳足迹的最小化，同时最大化产生的能量。这些潜在利益的结合可能是经济的，而没有补贴或关税扭曲市场。

As a civilisation, we generate an enormous amount of food waste with over 2 billion tonnes produced per year, much of which can be utilised as energy using AD in a sustainable manner if properly processed. The EU, with UK being the leading offender, generates over 89 MT of food waste per year. This waste can be redistributed as food source for animals as a first step, but with that failing, it is better to recover the energy using AD. AD represents nutrient recovery and is a preferred option over all other means of waste management as prescribed by the Waste Food Hierarchy discussed in the 2015 House of Lords report on food waste. AD is a process which converts food waste or biomass or manure in anaerobic (without presence of air) conditions by the breakdown of higher chain compounds into methane and other lower chain compounds. This process conventionally follows the following steps - 1. Placing biomass (wet food waste) into sealed air tight container 2. Digestion of this biomass(wet food waste) using anaerobic microbes present in the system to produce methane rich biogas to be used for energy generation 3. Digestate to be used as manure or compostThe pathway we are proposing is replacing the airtight container with fluidically oscillated CO2 rich microbubbles obtained by sweetening of the flue gas on-site using CaCaCa process[1] and microbubble technology[2-5]. Periodic injection (5 minute) of CO2 rich microbubbles has shown to increase CH4 production by 110% as compared to the conventional process. This is a dual pronged process with removal of metabolites/wastes by microbubble stripping and simultaneous nutrient injection. The CH4 generated can be used for energy generation thereby offsetting fossil fuel use and reduce Greenhouse Gas (GHG) Emissions . We get the CO2 rich microbubbles by sweetening biogas gas using the CaCaCa process in order to capture the CH4 which is then burnt and the flue gas is CO2 rich (potentially with water vapour which can be easily condensed. This is further self sustaining since the burning of the CH4 produced in the first step leads to flue gas generation. The fluidic oscillator for microbubble generation underpins the sweetening and methanogenesis (the process in AD wherein methane is generated). This greatly increases the value of products formed in AD whilst consuming the CO2 generated thereby further offsetting GHG emissions. Recovering the heat from the process add to this energy balance which can be used for on-site heating via Combined Heat and Power (CHP). The project is going to investigate the onsite prototype build of this novel fluidically oscillated CO2 rich microbubble process for AD and simultaneous sweetening of the flue gas generated using the CaCaCa process optimised with Perlemax's fluidic oscillator driven microbubbles. The CHP and CH4 generation can be further increased by optimisation of the process variables as discussed in AppendixB part 2. This would possibly increase CH4 generation over the slated 110%. This ensures a minimisation of the carbon footprint whilst maximisation of the energy generated for the same. The combination of these potential benefits could be economic without subsidy or tariff skewing the market.