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

作为一个文明，我们产生了大量的食物垃圾，每年产生超过20亿吨，如果处理得当，其中大部分可以作为能源利用AD以可持续的方式利用。以英国为首的欧盟每年产生超过公吨的食物垃圾。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代表养分回收，是2015年上议院关于食物垃圾的报告中讨论的垃圾食物等级所规定的所有其他废物管理手段的首选选择。AD是一种在厌氧(无空气)条件下将食物垃圾或生物质或粪便转化为甲烷和其他低链化合物的过程。这一过程通常遵循以下步骤-1.将生物质(湿食物垃圾)放入密封的密闭容器中2.使用系统中存在的厌氧微生物消化该生物质(湿食物垃圾)，以产生用于发电的富甲烷沼气3.沼气用作粪便或堆肥我们提出的方法是用流体振荡的富含二氧化碳的微气泡取代密封容器，该微气泡是通过使用CaCa工艺[1]和微泡技术[2-5]现场对烟道气进行脱臭而获得的。定期注入富含二氧化碳的微泡(5分钟)，与传统工艺相比，甲烷产量增加了110%。这是一个双管齐下的过程，通过微泡汽提和同时注入养分来去除代谢物/废物。产生的甲烷可用于能源生产，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工艺对沼气进行脱臭处理来获得富含二氧化碳的微气泡，以捕获甲烷，然后燃烧甲烷，烟道气是富含二氧化碳的(可能带有易于冷凝的水蒸气)。这是进一步的自我维持，因为燃烧第一步产生的CH4会导致烟道气的产生。用于产生微泡的流体振荡器支持甜味和甲烷生成(AD中产生甲烷的过程)。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能量平衡，可通过热电联产(CHP)用于现场供暖。该项目将研究用于AD的这种新型流体振荡富CO2微泡工艺的现场原型建造，以及使用Perlemax的流体振荡器驱动的微泡优化的CaCaCa工艺产生的烟气的同时脱臭。CHP和CH4的产生量可以通过优化工艺变量进一步增加，如附录B第2部分所述。这可能会使CH4的产生量增加110%。这确保了最大限度地减少碳足迹，同时最大限度地提高了产生的能量。在没有补贴或关税扭曲市场的情况下，这些潜在好处的组合可能是经济的。

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.